ValueError：第 0 年超出范围 seaborn

Question

I am struggling to plot a simple time series with seaborn and can't understand why this hasn't work. My dataframe time_series give daily data for patients from 2015 to 2019 and also has a datetime index.It looks as such:

            patients
Date                
2015-01-04        49
2015-01-05        51
2015-01-06        48
2015-01-07        30
2015-01-08        27

I am trying to build a scatter plot, however upon building it, it starts at 2000 and therefore all the data points are to the right of the graph. I tried to counter this by setting an xlim but am receiving a strange error. My code is as such:

import seaborn as sns
import matplotlib.pyplot as plt

sns.scatterplot(x=time_series.index, y=time_series['patients'])
plt.xlim(2015,2019)

This is the error which I don't understand as I have no year '0':

ValueError: year 0 is out of range

Can anyone help me out here. Many Thanks

Answer 1

• The issue seems to be that the datetime information from the df.index is converted to a datetime ordinal representation for the plot locs .
• If you use locs, labels = plt.xticks() , comment out plt.xlim and print locs , you will see they are array([729390.00000485, 730120.00000485, 730851.00000485, 731581.00000485, 732312.00000485, 733042.00000485, 733773.00000485, 734503.00000485, 735234.00000485, 735964.00000485]) . So when you set plt.xlim(2015, 2019) you are not in the range of the locs being plotted. The years are just labels.
• Given your sample dataframe with the a datetime index

from datetime import date, datetime

# determine ordinal value for desired date range
print(date.toordinal(datetime(2015, 1, 1, 0, 0)))
>>>735599
print(date.toordinal(datetime(2019, 1, 1, 0, 0)))
>>>737060

chart = sns.scatterplot(x=df.index, y=df['patients'])
plt.xlim(735599, 737060)

plt.setp(chart.get_xticklabels(), rotation=45)
plt.show()