Python & Matplotlib, plot multiple and different and uncontinuous time series

Question

I guess this is a simple question, but I've been trying for hours with no results. I have a dict that I want to see in a chart in matplotlib

• At this time I'm only using the values of the dict, the keys will be used latter.
• The values are lists of tuples, each tuple is a pair of a date and a number.
• The lists have different lengths, and, within them, the dates have different starts and ends, and all time frames are progressive but with no sequence.
• The dict can vary because is generated by the user, but it will have the same structure.
• I want to create a chart with as many lines as the length of the dict.
• XAxis with numbers and YAxis with dates

_mat_graph =
{'AFG': [(datetime.datetime(2021, 2, 22, 0, 0), 0.0),
         (datetime.datetime(2021, 2, 28, 0, 0), 8200.0),
         (datetime.datetime(2021, 3, 16, 0, 0), 54000.0),
         (datetime.datetime(2021, 4, 7, 0, 0), 120000.0),
         (datetime.datetime(2021, 4, 22, 0, 0), 240000.0),
         (datetime.datetime(2021, 5, 11, 0, 0), 448878.0)]
 'ALB': [(datetime.datetime(2021, 1, 10, 0, 0), 0.0),
         (datetime.datetime(2021, 1, 12, 0, 0), 128.0),
         (datetime.datetime(2021, 1, 13, 0, 0), 188.0),
         (datetime.datetime(2021, 1, 14, 0, 0), 266.0),
         (datetime.datetime(2021, 1, 15, 0, 0), 308.0),
         (datetime.datetime(2021, 1, 16, 0, 0), 369.0),
         (datetime.datetime(2021, 1, 17, 0, 0), 405.0),
         (datetime.datetime(2021, 1, 18, 0, 0), 447.0),
         (datetime.datetime(2021, 1, 19, 0, 0), 483.0),
         (datetime.datetime(2021, 1, 20, 0, 0), 519.0),
         (datetime.datetime(2021, 1, 21, 0, 0), 549.0),
         (datetime.datetime(2021, 2, 2, 0, 0), 549.0),
         (datetime.datetime(2021, 2, 9, 0, 0), 689.0),
         (datetime.datetime(2021, 2, 17, 0, 0), 1090.0),
         (datetime.datetime(2021, 2, 18, 0, 0), 2438.0),
         (datetime.datetime(2021, 2, 22, 0, 0), 6073.0),
         (datetime.datetime(2021, 5, 11, 0, 0), 440921.0),
         (datetime.datetime(2021, 5, 12, 0, 0), 444755.0),
         (datetime.datetime(2021, 5, 13, 0, 0), 445402.0),
         (datetime.datetime(2021, 5, 14, 0, 0), 448571.0)]
 'AND': [(datetime.datetime(2021, 1, 25, 0, 0), 576.0),
         (datetime.datetime(2021, 2, 1, 0, 0), 1036.0),
         (datetime.datetime(2021, 2, 10, 0, 0), 1291.0),
         (datetime.datetime(2021, 2, 12, 0, 0), 1622.0),
         (datetime.datetime(2021, 2, 19, 0, 0), 2141.0),
         (datetime.datetime(2021, 2, 24, 0, 0), 2390.0),
         (datetime.datetime(2021, 3, 8, 0, 0), 2439.0),
         (datetime.datetime(2021, 3, 10, 0, 0), 3650.0),
         (datetime.datetime(2021, 3, 15, 0, 0), 7098.0),
         (datetime.datetime(2021, 4, 5, 0, 0), 9781.0),
         (datetime.datetime(2021, 4, 19, 0, 0), 21733.0),
         (datetime.datetime(2021, 4, 26, 0, 0), 23822.0),
         (datetime.datetime(2021, 5, 3, 0, 0), 24182.0),
         (datetime.datetime(2021, 5, 10, 0, 0), 26931.0)]}

Now, this is the (not working...) code I'm using (SAFE_COLORS is a dict of lists of rgb colors in hex):

from datetime import datetime, timedelta
import matplotlib.pyplot as plt
from matplotlib.dates import drange
import numpy as np

cont = 0
for _iso, _entries in _mat_graph.items():
    graph_dates = drange(_entries[0][0], _entries[-1][0], timedelta(days=1))
    cantidades = np.array([x[1] for x in _entries])
    plt.plot_date(
        graph_dates,
        cantidades,
        color=SAFE_COLORS[12][cont],
        marker='.'
    )
    cont += 1
plt.show()

And this is the error I get:

path\to\pyfiles\main.py:1055: UserWarning: marker is redundantly defined by the 'marker' keyword argument and the fmt string "o" (-> marker='o'). The keyword argument will take precedence.
  plt.plot_date(
Traceback (most recent call last):
  File "path\to\pyfiles\main.py", line 1055, in <module> plt.plot_date(
  File "path\to\pyfiles\.venv\lib\site-packages\matplotlib\pyplot.py", line 3029, in plot_date
    return gca().plot_date(
  File "path\to\pyfiles\.venv\lib\site-packages\matplotlib\__init__.py", line 1361, in inner
    return func(ax, *map(sanitize_sequence, args), **kwargs)
  File "path\to\pyfiles\.venv\lib\site-packages\matplotlib\axes\_axes.py", line 1676, in plot_date
    return self.plot(x, y, fmt, **kwargs)
  File "path\to\pyfiles\.venv\lib\site-packages\matplotlib\axes\_axes.py", line 1605, in plot
    lines = [*self._get_lines(*args, data=data, **kwargs)]
  File "path\to\pyfiles\.venv\lib\site-packages\matplotlib\axes\_base.py", line 315, in __call__
    yield from self._plot_args(this, kwargs)
  File "path\to\pyfiles\.venv\lib\site-packages\matplotlib\axes\_base.py", line 501, in _plot_args
    raise ValueError(f"x and y must have same first dimension, but "
ValueError: x and y must have same first dimension, but have shapes (78,) and (6,)

Any help will be appreciated, thanks in advance,

Answer 1

I'm not exactly sure what you are trying to do with the graph_dates above, but my guess is that is your problem. Simplest is:

fig, ax = plt.subplots(constrained_layout=True)
plt.rcParams['date.converter'] = 'concise'
for key, data in _mat_graph.items():
    date = [x[0] for x in data]
    data = [x[1] for x in data]
    ax.plot(date, data, '.', ms=10, label=key)
ax.legend()
plt.show()