updated readme

rasbt · rasbt · commit edc17e290748 · 2015-02-06T11:58:24.000-05:00
diff --git a/README.md b/README.md
@@ -154,11 +154,11 @@
 
 - [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>
 
diff --git a/useful_scripts/sparsify_matrix.py b/useful_scripts/sparsify_matrix.py
@@ -4,6 +4,8 @@
 # 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]])
