AbtPst AbtPst - 8 days ago 6
Python Question

Matplotlib : Cant create log plots

I am iterating over each column of a dataframe and trying to create log plots as

cols = in_df.columns

for col in cols:
in_df[col]=in_df[col].dropna()
print (in_df[col].values)
in_df[col].map(np.log).hist(bins=1000)
plt.xlabel(x_label+col)
plt.ylabel('Number of customers in train')
plt.savefig(save_dir+col+'.png')
plt.close()


but i get

[2 2 2 ..., 2 2 2]
in_df[col].map(np.log).hist(bins=1000)
File "anaconda/envs/kaggle3/lib/python3.5/site-packages/pandas/tools/plotting.py", line 2988, in hist_series
ax.hist(values, bins=bins, **kwds)
File "anaconda/envs/kaggle3/lib/python3.5/site-packages/matplotlib/__init__.py", line 1819, in inner
return func(ax, *args, **kwargs)
File "anaconda/envs/kaggle3/lib/python3.5/site-packages/matplotlib/axes/_axes.py", line 5985, in hist
m, bins = np.histogram(x[i], bins, weights=w[i], **hist_kwargs)
File "anaconda/envs/kaggle3/lib/python3.5/site-packages/numpy/lib/function_base.py", line 505, in histogram
'range parameter must be finite.')
ValueError: range parameter must be finite.


note that the following works

in_df.col_name.map(np.log).hist(bins=1000)


how ever i cant use this approach while iterating over all of the columns. any idea why am i getting the error?

Answer

If I'm right about the zeros, easiest way to fix your problem is to drop them. There are a bunch of ways to do it. Below is one:

cols = in_df.columns

for col in cols:
    in_df[col]=in_df[col].dropna()
    print (in_df[col].values)
    # I edited line below
    in_df[col].replace(0, np.nan).dropna().map(np.log).hist(bins=1000)
    # added   |<------------------------>|
    plt.xlabel(x_label+col)
    plt.ylabel('Number of customers in train')
    plt.savefig(save_dir+col+'.png')
    plt.close()