mirror of
https://github.com/rasbt/python_reference.git
synced 2025-01-18 07:17:06 +00:00
fix grammatical errors and confusing wording
This commit is contained in:
BrandonThaiTran
parent
d6ddacb2d4
commit
ff679bcaf1
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@ -12,9 +12,12 @@
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},
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{
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"cell_type": "code",
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"execution_count": 1,
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"execution_count": null,
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"metadata": {
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"collapsed": false
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"collapsed": false,
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"jupyter": {
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"outputs_hidden": false
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}
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},
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"outputs": [],
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"source": [
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@ -23,22 +26,14 @@
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},
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{
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"cell_type": "code",
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"execution_count": 2,
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"execution_count": null,
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"metadata": {
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"collapsed": false
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},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"Sebastian Raschka 01/27/2016 \n",
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"\n",
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"CPython 3.5.1\n",
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"IPython 4.0.3\n"
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]
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"collapsed": false,
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"jupyter": {
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"outputs_hidden": false
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}
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],
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},
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"outputs": [],
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"source": [
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"%watermark -a 'Sebastian Raschka' -v -d"
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]
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@ -166,7 +161,7 @@
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"Now, the tricky part is that we have multiple independent namespaces in Python, and names can be reused for different namespaces (only the objects are unique, for example:\n",
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"Now, the tricky part is that we have multiple independent namespaces in Python, and names can be reused for different namespaces. Only the objects in namespaces are unique, for example:\n",
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"\n",
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"<pre>a_namespace = {'name_a':object_1, 'name_b':object_2, ...}\n",
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"b_namespace = {'name_a':object_3, 'name_b':object_4, ...}</pre>\n",
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@ -191,20 +186,14 @@
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},
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{
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"cell_type": "code",
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"execution_count": 1,
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"execution_count": null,
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"metadata": {
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"collapsed": false
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},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"1 global\n",
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"5 in foo()\n"
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]
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"collapsed": false,
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"jupyter": {
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"outputs_hidden": false
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}
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],
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},
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"outputs": [],
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"source": [
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"i = 1\n",
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"\n",
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@ -250,21 +239,14 @@
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},
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{
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"cell_type": "code",
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"execution_count": 11,
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"execution_count": null,
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"metadata": {
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"collapsed": false
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},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"loc in foo(): True\n",
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"loc in global: False\n",
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"glob in global: True\n"
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]
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"collapsed": false,
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"jupyter": {
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"outputs_hidden": false
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}
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],
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},
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"outputs": [],
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"source": [
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"#print(globals()) # prints global namespace\n",
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"#print(locals()) # prints local namespace\n",
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@ -277,7 +259,8 @@
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"\n",
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"foo()\n",
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"print('loc in global:', 'loc' in globals()) \n",
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"print('glob in global:', 'foo' in globals())"
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"print('glob in global:', 'glob' in globals())\n",
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"print('foo in global:', 'foo' in globals())"
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]
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},
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{
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@ -299,7 +282,7 @@
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"where the arrows should denote the direction of the namespace-hierarchy search order. \n",
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"\n",
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"- *Local* can be inside a function or class method, for example. \n",
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"- *Enclosed* can be its `enclosing` function, e.g., if a function is wrapped inside another function. \n",
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"- *Enclosed* can be variables of an`enclosing` function, e.g., if a function is wrapped inside another function. \n",
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"- *Global* refers to the uppermost level of the executing script itself, and \n",
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"- *Built-in* are special names that Python reserves for itself. \n",
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"\n",
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@ -311,21 +294,14 @@
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},
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{
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"cell_type": "code",
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"execution_count": 8,
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"execution_count": null,
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"metadata": {
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"collapsed": false
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},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"3.141592653589793 from the math module\n",
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"3.141592653589793 from the numpy package\n",
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"3.141592653589793 from the scipy package\n"
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]
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"collapsed": false,
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"jupyter": {
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"outputs_hidden": false
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}
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],
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},
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"outputs": [],
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"source": [
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"import numpy\n",
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"import math\n",
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@ -347,11 +323,7 @@
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"<br>\n",
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"<br>\n",
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"\n",
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"<br>\n",
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"<br>"
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""
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]
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},
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{
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@ -381,9 +353,12 @@
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},
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{
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"cell_type": "code",
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"execution_count": 1,
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"execution_count": null,
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"metadata": {
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"collapsed": false
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"collapsed": false,
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"jupyter": {
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"outputs_hidden": false
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}
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},
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"outputs": [],
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"source": [
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@ -427,7 +402,7 @@
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"source": [
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"### Here is why:\n",
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"\n",
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"We call `a_func()` first, which is supposed to print the value of `a_var`. According to the LEGB rule, the function will first look in its own local scope (L) if `a_var` is defined there. Since `a_func()` does not define its own `a_var`, it will look one-level above in the global scope (G) in which `a_var` has been defined previously.\n",
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"We call `a_func()` first, which is supposed to print the value of `a_var`. According to the LEGB rule, the function will first look in its own local scope (L) if `a_var` is defined there. Since `a_func()` does not define its own `a_var`, it will look two levels above (Local-> Enclosed -> Global) in the global scope (G) in which `a_var` has been defined previously.\n",
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"<br>\n",
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"<br>"
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]
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@ -443,9 +418,12 @@
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},
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{
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"cell_type": "code",
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"execution_count": 2,
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"execution_count": null,
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"metadata": {
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"collapsed": false
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"collapsed": false,
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"jupyter": {
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"outputs_hidden": false
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}
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},
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"outputs": [],
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"source": [
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@ -501,21 +479,14 @@
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},
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{
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"cell_type": "code",
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"execution_count": 3,
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"execution_count": null,
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"metadata": {
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"collapsed": false
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},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"global value [ a_var outside a_func() ]\n",
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"local value [ a_var inside a_func() ]\n",
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"local value [ a_var outside a_func() ]\n"
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]
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"collapsed": false,
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"jupyter": {
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"outputs_hidden": false
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}
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],
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},
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"outputs": [],
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"source": [
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"a_var = 'global value'\n",
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"\n",
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@ -538,30 +509,14 @@
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},
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{
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"cell_type": "code",
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"execution_count": 4,
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"execution_count": null,
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"metadata": {
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"collapsed": false
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},
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"outputs": [
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{
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"ename": "UnboundLocalError",
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"evalue": "local variable 'a_var' referenced before assignment",
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"output_type": "error",
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"traceback": [
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"\u001b[0;31m---------------------------------------------------------------------------\u001b[0m\n\u001b[0;31mUnboundLocalError\u001b[0m Traceback (most recent call last)",
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"\u001b[0;32m<ipython-input-4-a6cdd0ee9a55>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m()\u001b[0m\n\u001b[1;32m 6\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m 7\u001b[0m \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0ma_var\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;34m'[ a_var outside a_func() ]'\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 8\u001b[0;31m \u001b[0ma_func\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
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"\u001b[0;32m<ipython-input-4-a6cdd0ee9a55>\u001b[0m in \u001b[0;36ma_func\u001b[0;34m()\u001b[0m\n\u001b[1;32m 2\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m 3\u001b[0m \u001b[0;32mdef\u001b[0m \u001b[0ma_func\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 4\u001b[0;31m \u001b[0ma_var\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0ma_var\u001b[0m \u001b[0;34m+\u001b[0m \u001b[0;36m1\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m 5\u001b[0m \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0ma_var\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;34m'[ a_var inside a_func() ]'\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m 6\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n",
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"\u001b[0;31mUnboundLocalError\u001b[0m: local variable 'a_var' referenced before assignment"
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]
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},
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"1 [ a_var outside a_func() ]\n"
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]
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"collapsed": false,
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"jupyter": {
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"outputs_hidden": false
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}
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],
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},
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"outputs": [],
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"source": [
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"a_var = 1\n",
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"\n",
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@ -573,6 +528,30 @@
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"a_func()"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"This is how to make the above code work:"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"a_var = 1\n",
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"\n",
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"def a_func():\n",
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" global a_var\n",
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" a_var = a_var + 1\n",
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" print(a_var, '[ a_var inside a_func() ]')\n",
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"\n",
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"print(a_var, '[ a_var outside a_func() ]')\n",
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"a_func()"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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@ -610,9 +589,12 @@
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},
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{
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"cell_type": "code",
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"execution_count": 4,
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"execution_count": null,
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"metadata": {
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"collapsed": false
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"collapsed": false,
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"jupyter": {
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"outputs_hidden": false
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}
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},
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"outputs": [],
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"source": [
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@ -657,7 +639,7 @@
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"source": [
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"### Here is why:\n",
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"\n",
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"Let us quickly recapitulate what we just did: We called `outer()`, which defined the variable `a_var` locally (next to an existing `a_var` in the global scope). Next, the `outer()` function called `inner()`, which in turn defined a variable with of name `a_var` as well. The `print()` function inside `inner()` searched in the local scope first (L->E) before it went up in the scope hierarchy, and therefore it printed the value that was assigned in the local scope."
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"Let us quickly recapitulate what we just did: We called `outer()`, which defined the variable `a_var` locally (next to an existing `a_var` in the global scope). Next, the `outer()` function called `inner()`, which in turn defined a variable with of name `a_var` as well. The `print()` function inside `inner()` searched in the local scope first (L) before it went up in the scope hierarchy, and therefore it printed the value that was assigned in the local scope."
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]
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},
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{
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@ -670,21 +652,14 @@
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},
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{
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"cell_type": "code",
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"execution_count": 5,
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"execution_count": null,
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"metadata": {
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"collapsed": false
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},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"outer before: local value\n",
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"in inner(): inner value\n",
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"outer after: inner value\n"
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]
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"collapsed": false,
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"jupyter": {
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"outputs_hidden": false
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}
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],
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},
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"outputs": [],
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"source": [
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"a_var = 'global value'\n",
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"\n",
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@ -715,7 +690,7 @@
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"source": [
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"## 3. LEGB - Local, Enclosed, Global, Built-in\n",
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"\n",
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"To wrap up the LEGB rule, let us come to the built-in scope. Here, we will define our \"own\" length-funcion, which happens to bear the same name as the in-built `len()` function. What outcome do you excpect if we'd execute the following code?"
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"To wrap up the LEGB rule, let us come to the built-in scope. Here, we will define our \"own\" length-funcion, which happens to bear the same name as the in-built `len()` function. What outcome do you expect if we'd execute the following code?"
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]
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},
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{
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@ -727,9 +702,12 @@
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},
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{
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"cell_type": "code",
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"execution_count": 6,
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"execution_count": null,
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"metadata": {
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"collapsed": false
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"collapsed": false,
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"jupyter": {
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"outputs_hidden": false
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}
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},
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"outputs": [],
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"source": [
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@ -805,9 +783,12 @@
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},
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{
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"cell_type": "code",
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"execution_count": 59,
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"execution_count": null,
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"metadata": {
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"collapsed": false
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"collapsed": false,
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"jupyter": {
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"outputs_hidden": false
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}
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},
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"outputs": [],
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"source": [
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@ -887,19 +868,14 @@
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},
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{
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"cell_type": "code",
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"execution_count": 42,
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"execution_count": null,
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"metadata": {
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"collapsed": false
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},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"8\n"
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]
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"collapsed": false,
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"jupyter": {
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"outputs_hidden": false
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}
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],
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},
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"outputs": [],
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"source": [
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"a_var = 2\n",
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"\n",
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@ -930,9 +906,12 @@
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},
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{
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"cell_type": "code",
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"execution_count": 6,
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"execution_count": null,
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"metadata": {
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"collapsed": false
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"collapsed": false,
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"jupyter": {
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"outputs_hidden": false
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}
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},
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"outputs": [],
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"source": [
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@ -941,9 +920,12 @@
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},
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{
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"cell_type": "code",
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"execution_count": 7,
|
||||
"execution_count": null,
|
||||
"metadata": {
|
||||
"collapsed": false
|
||||
"collapsed": false,
|
||||
"jupyter": {
|
||||
"outputs_hidden": false
|
||||
}
|
||||
},
|
||||
"outputs": [],
|
||||
"source": [
|
||||
|
|
@ -952,9 +934,12 @@
|
|||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"execution_count": 8,
|
||||
"execution_count": null,
|
||||
"metadata": {
|
||||
"collapsed": false
|
||||
"collapsed": false,
|
||||
"jupyter": {
|
||||
"outputs_hidden": false
|
||||
}
|
||||
},
|
||||
"outputs": [],
|
||||
"source": [
|
||||
|
|
@ -963,9 +948,12 @@
|
|||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"execution_count": 9,
|
||||
"execution_count": null,
|
||||
"metadata": {
|
||||
"collapsed": false
|
||||
"collapsed": false,
|
||||
"jupyter": {
|
||||
"outputs_hidden": false
|
||||
}
|
||||
},
|
||||
"outputs": [],
|
||||
"source": [
|
||||
|
|
@ -974,9 +962,12 @@
|
|||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"execution_count": 58,
|
||||
"execution_count": null,
|
||||
"metadata": {
|
||||
"collapsed": false
|
||||
"collapsed": false,
|
||||
"jupyter": {
|
||||
"outputs_hidden": false
|
||||
}
|
||||
},
|
||||
"outputs": [],
|
||||
"source": [
|
||||
|
|
@ -1024,20 +1015,14 @@
|
|||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"execution_count": 5,
|
||||
"execution_count": null,
|
||||
"metadata": {
|
||||
"collapsed": false
|
||||
},
|
||||
"outputs": [
|
||||
{
|
||||
"name": "stdout",
|
||||
"output_type": "stream",
|
||||
"text": [
|
||||
"4 -> a in for-loop\n",
|
||||
"4 -> a in global\n"
|
||||
]
|
||||
"collapsed": false,
|
||||
"jupyter": {
|
||||
"outputs_hidden": false
|
||||
}
|
||||
],
|
||||
},
|
||||
"outputs": [],
|
||||
"source": [
|
||||
"for a in range(5):\n",
|
||||
" if a == 4:\n",
|
||||
|
|
@ -1054,20 +1039,14 @@
|
|||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"execution_count": 9,
|
||||
"execution_count": null,
|
||||
"metadata": {
|
||||
"collapsed": false
|
||||
},
|
||||
"outputs": [
|
||||
{
|
||||
"name": "stdout",
|
||||
"output_type": "stream",
|
||||
"text": [
|
||||
"4 -> b in for-loop\n",
|
||||
"4 -> b in global\n"
|
||||
]
|
||||
"collapsed": false,
|
||||
"jupyter": {
|
||||
"outputs_hidden": false
|
||||
}
|
||||
],
|
||||
},
|
||||
"outputs": [],
|
||||
"source": [
|
||||
"b = 1\n",
|
||||
"for b in range(5):\n",
|
||||
|
|
@ -1085,20 +1064,14 @@
|
|||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"execution_count": 1,
|
||||
"execution_count": null,
|
||||
"metadata": {
|
||||
"collapsed": false
|
||||
},
|
||||
"outputs": [
|
||||
{
|
||||
"name": "stdout",
|
||||
"output_type": "stream",
|
||||
"text": [
|
||||
"[0, 1, 2, 3, 4]\n",
|
||||
"1 -> i in global\n"
|
||||
]
|
||||
"collapsed": false,
|
||||
"jupyter": {
|
||||
"outputs_hidden": false
|
||||
}
|
||||
],
|
||||
},
|
||||
"outputs": [],
|
||||
"source": [
|
||||
"i = 1\n",
|
||||
"print([i for i in range(5)])\n",
|
||||
|
|
@ -1124,15 +1097,6 @@
|
|||
"\n",
|
||||
"\"List comprehensions no longer support the syntactic form `[... for var in item1, item2, ...]`. Use `[... for var in (item1, item2, ...)]` instead. Also note that list comprehensions have different semantics: they are closer to syntactic sugar for a generator expression inside a `list()` constructor, and in particular the loop control variables are no longer leaked into the surrounding scope.\""
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"execution_count": null,
|
||||
"metadata": {
|
||||
"collapsed": false
|
||||
},
|
||||
"outputs": [],
|
||||
"source": []
|
||||
}
|
||||
],
|
||||
"metadata": {
|
||||
|
|
@ -1151,9 +1115,9 @@
|
|||
"name": "python",
|
||||
"nbconvert_exporter": "python",
|
||||
"pygments_lexer": "ipython3",
|
||||
"version": "3.5.0"
|
||||
"version": "3.8.2"
|
||||
}
|
||||
},
|
||||
"nbformat": 4,
|
||||
"nbformat_minor": 0
|
||||
"nbformat_minor": 4
|
||||
}
|
||||
|
|
|
|||
Loading…
Reference in New Issue
Block a user