Undesired shadow in matplotlib pyplot

Question

I'm trying to plot some data for school project. However an ugly shadow appears when I do so. I have no clue of what it can be.

Here is my code:

index_labels = np.empty(len(smoothed), dtype=object)
for i in range(len(index_labels)):
    index_labels[i] = ""
    if i%365 == 0:
        index_labels[i] = 2015 + int(i//365)

plt.scatter(smoothed.index, smoothed.national, label='PV load factor rolling mean over 24h.')
plt.plot(smoothed.index, sin_ref, color='red', label='Sinusoidal reference')
ax = plt.gca()
ax.set_xticklabels(index_labels)
# plt.legend()
plt.show()

and here is the different variables used so you have an idea:

and a zoom on the plot :

Thanks to all of you! Greetings :)

That looks like thousands of ticks side-by-side. Probably worth looking at https://matplotlib.org/stable/api/ticker_api.html, instead of your current approach to creating `index_labels`. — BigBen, Sep 22 '22 at 19:15
With the line drop the problem is that the original x is crowded of values which create a second black line as follow: https://imgur.com/a/6xTGC4Q — TheBlackDev_, Sep 22 '22 at 19:18
Your solution works! Thank you :) Wanna answer the question or do I ? — TheBlackDev_, Sep 22 '22 at 19:21

score 2 · Answer 1 · edited Sep 24 '22 at 16:30

Solution from @BigBen:

from matplotlib.ticker import MultipleLocator

plt.scatter(smoothed.index, smoothed.national, label='PV load factor rolling mean over 24h.')
plt.plot(smoothed.index, sin_ref, color='red', label='Sinusoidal reference')
ax = plt.gca()
ax.xaxis.set_major_locator(MultipleLocator(730))
plt.show()

Multiple has a very good name: it only shows the label for the multiple of n.

EDIT: as find later, matplotlib do auto axis labeling for dates. Only problem was that column was recognized as string. pandas.to_datetime allow you to convert it back to pandas datetime type.

Undesired shadow in matplotlib pyplot

1 Answers1