matplotlib bar chart with multiple columns, dates on x axis

Question

I am trying to do a simple bar chart for a dataframe, that has dates as index and several columns of data.

start_date = pd.to_datetime('20180101')
dates = pd.date_range(start_date, periods=365)
df = pd.DataFrame(np.random.randn(365,4), index = dates, columns = list('ABCD'))
df = df.resample('M').sum()

If I use

df.plot.bar()

Then dates on the x-axis are messed up. If I use

fig, ax = plt.subplots()
ax.bar(df.index, df['A'],width = 5, align = 'center')
ax.bar(df.index, df['B'], width = 5 , align = 'center')
ax.bar(df.index, df['C'],width = 5, align = 'center')
ax.bar(df.index, df['D'], width = 5 , align = 'center')
ax.xaxis_date()
ax.get_xaxis().set_major_locator(mdates.MonthLocator())
ax.get_xaxis().set_major_formatter(mdates.DateFormatter("%b %Y"))
fig.autofmt_xdate()
plt.show()

Then my bars overlap each other and dates are shown with a shift by one month.

Can someone please suggest an elegant solution how to plot a bar chart that will not have the above mentioned drawbacks?

Pandas bar charts are catgorical. But to me the result looks fine. The shift of one month in the matplotlib chart is in your data, due to the resampling you perform. This example shows how to make a grouped barchart in matplotlib. — ImportanceOfBeingErnest
– ImportanceOfBeingErnest, Commented Oct 6, 2018 at 14:51

Marcus Grass · Accepted Answer · 2018-10-06 14:57:16Z

3

I did a similar project with bars and used this example to get the formatting correct.

Since i don't have the mdates values I can't run it to check if it's correct in your case but try doing this:

...
fig, ax = plt.subplots()
width = 5
ax.bar(df.index, df['A'], width, align = 'center')
ax.bar(df.index + width , df['B'], width, align = 'center')
ax.bar(df.index + 2*width, df['C'], width, align = 'center')
ax.bar(df.index + 3*width, df['D'], width, align = 'center')
ax.set_xticks(df.index + width) # sets the x-ticks to the middle of the cluster of bars
ax.xaxis_date()
...

answered Oct 6, 2018 at 14:57

Marcus Grass

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2 Comments

Evgeny Over a year ago

Thank you! I saw this solution as well, yet didnt manage to make it work with dates.

Quastiat Over a year ago

not sure if its only on my side, but I had to use df.index + datetime.timedelta(days=width) to obtain the desired output

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