使用matplotlib绘制网格时没有垂直线

Question

When I drawing pyploy.subplots from my DataFrame I have not vertical lines. DataFrame index look that:

df_month.index
DatetimeIndex(['2016-01-31', '2016-02-29', '2016-03-31', '2016-04-30',
               '2016-05-31', '2016-06-30', '2016-07-31', '2016-08-31',
               '2016-09-30', '2016-10-31', '2016-11-30', '2016-12-31'],
              dtype='datetime64[ns]', freq='M')

I need vertical line for every row. Actually my figure looks that(when I increase time interval, there is vertical line for every January's indexes):

It is a code for it:

seaborn.set()
fig, axis = plt.subplots(nrows=6, sharex=True)

df_month.sum(axis=1).plot(ax=axis[0], marker = '.')

axis[0].set_title('Sum of costs')

for index, category in enumerate(df_month.columns.unique(), start=1):
    df_month[category].sum(axis=1).plot(ax=axis[index], marker = '.')
    axis[index].set_title(category)

plt.show()

Answer 1

You have to plot grid lines for minor and major ticks individually for every axes object ax with commands:

ax.grid(b='on', which='major', color='k', linewidth=.5)
ax.grid(b='on', which='minor', color='k', linewidth=.25)

You have to implement this code in a cycle over all axes objects of your subplots.

Look for more info here: https://matplotlib.org/api/_as_gen/matplotlib.axes.Axes.grid.html