按月绘制条形图-Matplotlib

Question

I have a dataset that is in the following form:

Date        A   B   C
01/04/2012  2   5   Y
05/04/2012  3   4   Y
06/05/2012  7   6   Y
09/05/2012  8   2   N
11/05/2012  1   4   Y
15/06/2012  5   4   Y

That continues on with more rows.

I want to plot a bar chart with date on the bottom axis converted to show just the month (ie April, May, July) and then on the y-axis I want the average of the sum of the A and B column so for the month of April it would be 7 (14 total over two instances) and for May it would be 9.33 (28 total over 3 instances).

I'm really struggling with how to do this and I'd prefer not to create another column that sums up A and B.

Answer 1

You can use groupby on month_name then mean + eval :

df['Date'] = pd.to_datetime(df['Date'], dayfirst=True)
df.groupby([df['Date'].dt.month_name()], sort=False).mean().eval('A+B')\
  .plot(kind='bar')

---

print(df.groupby([df['Date'].dt.month_name()], sort=False).mean().eval('A+B'))
Date
April    7.000000
May      9.333333
June     9.000000
dtype: float64