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updated readme

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rasbt 2015-02-06 11:58:24 -05:00
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README.md
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- [Shell script](./useful_scripts/prepend_python_shebang.sh) For prepending Python-shebangs to .py files.
- Convert 'tab-delimited' to 'comma-separated' CSV files [[IPython nb](http://nbviewer.ipython.org/github/rasbt/python_reference/blob/master/useful_scripts/fix_tab_csv.ipynb)]
- A random string generator [function](./useful_scripts/random_string_generator.py)
- A random string generator [function](./useful_scripts/random_string_generator.py).
- [Converting large CSV files](https://github.com/rasbt/python_reference/blob/master/useful_scripts/large_csv_to_sqlite.py) to SQLite databases using pandas.
- [Sparsifying a matrix](https://github.com/rasbt/python_reference/blob/master/useful_scripts/sparsify_matrix.py) by zeroing out all elements but the top k elements in a row using NumPy.
<br>

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useful_scripts/sparsify_matrix.py
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# The matrix could be a distance or similarity matrix (e.g., kernel matrix in kernel PCA),
# where we are interested to keep the top k neighbors.
import numpy as np
print('Sparsify a matrix by zeroing all elements but the top 2 values in a row.\n')
A = np.array([[1,2,3,4,5],[9,8,6,4,5],[3,1,7,8,9]])