CODEWITHSUNDEEP
pythonpandasmatplotlib
leofields
leofields

Reputation: 669

matplotlib: How to plot_date without clipping NaN at the beginning and end

I have values (np.array) I want to plot against index (DateTimeIndex) with ax.plot_date. Both have the same length.

>>>index 
DatetimeIndex(['1997-12-30', '1997-12-31', '1998-01-01', '1998-01-02',
               '1998-01-05', '1998-01-06', '1998-01-07', '1998-01-08',
               '1998-01-09', '1998-01-12',
               ...
               '2015-12-29', '2015-12-30', '2015-12-31', '2016-01-01',
               '2016-01-04', '2016-01-05', '2016-01-06', '2016-01-07',
               '2016-01-08', '2016-01-11'],
              dtype='datetime64[ns]', length=4705, freq='B')

>>>values
array([        nan,         nan,         nan, ...,  1.40211106,
    1.46409254,  1.36151557])

Now ax.plot_date(index, values) works fine except it will just clip the line at the beginning (the nan's) where I want to have the gap instead. I have no idea how to achieve this.

Upvotes: 3

Views: 1061

Answers (1)

Dan
Dan

Reputation: 2847

You need to set the xtick labels manually, here's an example with only 4 items in the index, and 2 values in values:

import pandas as pd
import pylab as plt
import numpy as np

#my made up data
index = pd.DatetimeIndex(['1997-12-30', '1997-12-31', '1998-01-01',
'1998-01-02'])
values = np.array([np.nan, np.nan, 1.402, 1.464]) 

#we are actually using this array as the x values in our graph, then replacing the labels with dates
x = np.arange(len(index))

#create plot
fig, ax = plt.subplots()
ax.set_xlim([0,len(index)])

#create axes with dates along the x axis
ax.set(xticks=x, xticklabels = index)

#plot values with the corresponding dates
ax.plot_date(x, values)

#show plot
plt.show()

Upvotes: 2

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