Learn how easy it is to sync an existing GitHub or Google Code repo to a SourceForge project!

## [matplotlib-devel] spy: ignore zero values in sparse matrix

 [matplotlib-devel] spy: ignore zero values in sparse matrix From: Tony S Yu - 2008-09-26 17:41:01 ```When sparse matrices have explicit zero values, `axes.spy` plots those zero values. This behavior seems unintentional. For example, the following code should have a main diagonal with markers missing in the middle, but `spy` currently plots a full main diagonal. #~~~~~~~~~~~ import scipy.sparse as sparse import matplotlib.pyplot as plt sp = sparse.spdiags([[1,1,1,0,0,0,1,1,1]], [0], 9, 9) plt.spy(sp, marker='.') #~~~~~~~~~~~ Below is a patch which only plots the nonzero entries in a sparse matrix. Note, sparse matrices with all zero entries raises an error; this behavior differs from dense matrices. I could change this behavior, but I wanted to minimize the code changed. Cheers, -Tony PS: this patch also includes two trivial changes to some examples. Index: lib/matplotlib/axes.py =================================================================== --- lib/matplotlib/axes.py (revision 6122) +++ lib/matplotlib/axes.py (working copy) @@ -6723,9 +6723,11 @@ else: if hasattr(Z, 'tocoo'): c = Z.tocoo() - y = c.row - x = c.col - z = c.data + nonzero = c.data != 0. + if all(nonzero == False): + raise ValueError('spy cannot plot sparse zeros matrix') + y = c.row[nonzero] + x = c.col[nonzero] else: Z = np.asarray(Z) if precision is None: mask = Z!=0. Index: examples/pylab_examples/masked_demo.py =================================================================== --- examples/pylab_examples/masked_demo.py (revision 6122) +++ examples/pylab_examples/masked_demo.py (working copy) @@ -1,4 +1,4 @@ -#!/bin/env python +#!/usr/bin/env python ''' Plot lines with points masked out. Index: examples/misc/rec_groupby_demo.py =================================================================== --- examples/misc/rec_groupby_demo.py (revision 6122) +++ examples/misc/rec_groupby_demo.py (working copy) @@ -2,7 +2,7 @@ import matplotlib.mlab as mlab -r = mlab.csv2rec('data/aapl.csv') +r = mlab.csv2rec('../data/aapl.csv') r.sort() def daily_return(prices): ```