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Fix bug and edit doctests for infix_to_prefix_conversion (#10259)
* Fix bug and edit doctests * [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci * Add type hints, raiseError and other minor adjustments * [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci * Cleaning code * [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci --------- Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
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hollowcrust
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@ -15,7 +15,7 @@ Enter an Infix Equation = a + b ^c
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"""
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def infix_2_postfix(infix):
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def infix_2_postfix(infix: str) -> str:
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"""
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>>> infix_2_postfix("a+b^c") # doctest: +NORMALIZE_WHITESPACE
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Symbol | Stack | Postfix
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@ -28,22 +28,35 @@ def infix_2_postfix(infix):
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| + | abc^
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| | abc^+
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'abc^+'
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>>> infix_2_postfix("1*((-a)*2+b)")
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Traceback (most recent call last):
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...
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KeyError: '('
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>>> infix_2_postfix("1*((-a)*2+b)") # doctest: +NORMALIZE_WHITESPACE
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Symbol | Stack | Postfix
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-------------------------------------------
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1 | | 1
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* | * | 1
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( | *( | 1
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( | *(( | 1
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- | *((- | 1
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a | *((- | 1a
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) | *( | 1a-
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* | *(* | 1a-
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2 | *(* | 1a-2
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+ | *(+ | 1a-2*
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b | *(+ | 1a-2*b
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) | * | 1a-2*b+
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| | 1a-2*b+*
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'1a-2*b+*'
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>>> infix_2_postfix("")
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Symbol | Stack | Postfix
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----------------------------
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''
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>>> infix_2_postfix("(()") # doctest: +NORMALIZE_WHITESPACE
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Symbol | Stack | Postfix
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----------------------------
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( | ( |
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( | (( |
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) | ( |
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| | (
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'('
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>>> infix_2_postfix("(()")
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Traceback (most recent call last):
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...
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ValueError: invalid expression
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>>> infix_2_postfix("())")
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Traceback (most recent call last):
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...
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@ -59,7 +72,7 @@ def infix_2_postfix(infix):
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"+": 1,
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"-": 1,
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} # Priority of each operator
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print_width = len(infix) if (len(infix) > 7) else 7
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print_width = max(len(infix), 7)
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# Print table header for output
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print(
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@ -76,6 +89,9 @@ def infix_2_postfix(infix):
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elif x == "(":
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stack.append(x) # if x is "(" push to Stack
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elif x == ")": # if x is ")" pop stack until "(" is encountered
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if len(stack) == 0: # close bracket without open bracket
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raise IndexError("list index out of range")
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while stack[-1] != "(":
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post_fix.append(stack.pop()) # Pop stack & add the content to Postfix
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stack.pop()
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@ -83,7 +99,7 @@ def infix_2_postfix(infix):
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if len(stack) == 0:
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stack.append(x) # If stack is empty, push x to stack
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else: # while priority of x is not > priority of element in the stack
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while len(stack) > 0 and priority[x] <= priority[stack[-1]]:
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while stack and stack[-1] != "(" and priority[x] <= priority[stack[-1]]:
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post_fix.append(stack.pop()) # pop stack & add to Postfix
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stack.append(x) # push x to stack
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@ -95,6 +111,9 @@ def infix_2_postfix(infix):
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) # Output in tabular format
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while len(stack) > 0: # while stack is not empty
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if stack[-1] == "(": # open bracket with no close bracket
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raise ValueError("invalid expression")
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post_fix.append(stack.pop()) # pop stack & add to Postfix
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print(
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" ".center(8),
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@ -106,7 +125,7 @@ def infix_2_postfix(infix):
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return "".join(post_fix) # return Postfix as str
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def infix_2_prefix(infix):
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def infix_2_prefix(infix: str) -> str:
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"""
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>>> infix_2_prefix("a+b^c") # doctest: +NORMALIZE_WHITESPACE
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Symbol | Stack | Postfix
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@ -119,10 +138,23 @@ def infix_2_prefix(infix):
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| | cb^a+
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'+a^bc'
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>>> infix_2_prefix("1*((-a)*2+b)")
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Traceback (most recent call last):
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...
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KeyError: '('
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>>> infix_2_prefix("1*((-a)*2+b)") # doctest: +NORMALIZE_WHITESPACE
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Symbol | Stack | Postfix
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-------------------------------------------
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( | ( |
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b | ( | b
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+ | (+ | b
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2 | (+ | b2
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* | (+* | b2
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( | (+*( | b2
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a | (+*( | b2a
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- | (+*(- | b2a
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) | (+* | b2a-
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) | | b2a-*+
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* | * | b2a-*+
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1 | * | b2a-*+1
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| | b2a-*+1*
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'*1+*-a2b'
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>>> infix_2_prefix('')
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Symbol | Stack | Postfix
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@ -134,26 +166,21 @@ def infix_2_prefix(infix):
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...
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IndexError: list index out of range
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>>> infix_2_prefix('())') # doctest: +NORMALIZE_WHITESPACE
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Symbol | Stack | Postfix
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----------------------------
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( | ( |
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( | (( |
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) | ( |
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| | (
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'('
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>>> infix_2_prefix('())')
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Traceback (most recent call last):
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...
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ValueError: invalid expression
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"""
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infix = list(infix[::-1]) # reverse the infix equation
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reversed_infix = list(infix[::-1]) # reverse the infix equation
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for i in range(len(infix)):
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if infix[i] == "(":
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infix[i] = ")" # change "(" to ")"
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elif infix[i] == ")":
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infix[i] = "(" # change ")" to "("
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for i in range(len(reversed_infix)):
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if reversed_infix[i] == "(":
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reversed_infix[i] = ")" # change "(" to ")"
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elif reversed_infix[i] == ")":
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reversed_infix[i] = "(" # change ")" to "("
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return (infix_2_postfix("".join(infix)))[
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::-1
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] # call infix_2_postfix on Infix, return reverse of Postfix
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# call infix_2_postfix on Infix, return reverse of Postfix
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return (infix_2_postfix("".join(reversed_infix)))[::-1]
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if __name__ == "__main__":
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