Fix bugs and documentation for stl_plot

[Mr-Geekman]

IMPORTANT: Please do not create a Pull Request without creating an issue first.

Before submitting (must do checklist)

• Did you read the contribution guide?
• Did you update the docs? We use Numpy format for all the methods and classes.
• Did you write any new necessary tests?
• Did you update the CHANGELOG?

Type of Change

• Examples / docs / tutorials / contributors update
• Bug fix (non-breaking change which fixes an issue)
• Improvement (non-breaking change which improves an existing feature)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Proposed Changes

Look #667

Related Issue

#667

Closing issues

Closes #667

[Mr-Geekman]

Example script:

import pandas as pd
import matplotlib.pyplot as plt

from etna.datasets import TSDataset
from etna.analysis import stl_plot


df = pd.read_csv("examples/data/example_dataset.csv")
df = TSDataset.to_dataset(df)
ts = TSDataset(df, freq="D")

stl_plot(ts=ts, segments=["segment_a"], period=7)
plt.savefig("plot_one_segment.png")

stl_plot(ts=ts, segments=["segment_a", "segment_b"], period=7)
plt.savefig("plot_two_segments.png")

stl_plot(ts=ts, segments=["segment_a", "segment_b", "segment_c"], period=7)
plt.savefig("plot_three_segments.png")

stl_plot(ts=ts, period=7)
plt.savefig("plot_four_segments.png")

plot_one_segment:

plot_two_segments:

plot_three_segments:

plot_four_

segments:

[github-actions]

🚀 Deployed on https://deploy-preview-685--etna-docs.netlify.app

[codecov-commenter]

Codecov Report

Merging #685 (cf95be1) into master (672a60a) will increase coverage by 0.12%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master     #685      +/-   ##
==========================================
+ Coverage   83.69%   83.81%   +0.12%     
==========================================
  Files         119      119              
  Lines        6401     6402       +1     
==========================================
+ Hits         5357     5366       +9     
+ Misses       1044     1036       -8     

Impacted Files	Coverage Δ
etna/analysis/eda_utils.py	48.65% <0.00%> (-0.17%)	⬇️
etna/transforms/nn/pytorch_forecasting.py	95.23% <0.00%> (+4.76%)	⬆️
etna/models/nn/tft.py	100.00% <0.00%> (+8.19%)	⬆️

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[martins0n]

5. Replace lines with axes preparation with `prepare_axes` from utils

What does it mean, should we fix it?

[Mr-Geekman]

I haven't figured out how to do it with current prepare_axes because in this particular plot we need firstly to create subfigures and just after this create subplots.

I am planning to change prepare_axes a little for a #663 but it make it suitable for this plot.