python - Can Pandas plot a histogram of dates?

Question

I've taken my Series and coerced it to a datetime column of dtype=datetime64[ns] (though only need day resolution...not sure how to change).

import pandas as pd
df = pd.read_csv('somefile.csv')
column = df['date']
column = pd.to_datetime(column, coerce=True)

but plotting doesn't work:

ipdb> column.plot(kind='hist')
*** TypeError: ufunc add cannot use operands with types dtype('<M8[ns]') and dtype('float64')

I'd like to plot a histogram that just shows the count of dates by week, month, or year.

Surely there is a way to do this in pandas?

Answer 1

Given this df:

        date
0 2001-08-10
1 2002-08-31
2 2003-08-29
3 2006-06-21
4 2002-03-27
5 2003-07-14
6 2004-06-15
7 2003-08-14
8 2003-07-29

and, if it's not already the case:

df["date"] = df["date"].astype("datetime64")

To show the count of dates by month:

df.groupby(df["date"].dt.month).count().plot(kind="bar")

.dt allows you to access the datetime properties.

Which will give you:

You can replace month by year, day, etc..

If you want to distinguish year and month for instance, just do:

df.groupby([df["date"].dt.year, df["date"].dt.month]).count().plot(kind="bar")

Which gives:

Was it what you wanted ? Is this clear ?

Hope this helps !