Plotting time in Python

Matplotlib understands datetimes; the formatter decides how they read.

import matplotlib

matplotlib.use("Agg")
import matplotlib.dates as mdates
import matplotlib.pyplot as plt
from datetime import date, timedelta

start = date(2026, 7, 20)
days = [start + timedelta(days=n) for n in range(10)]
tpm = [88, 90, 92, 97, 99, 101, 104, 103, 107, 110]

figure, axes = plt.subplots(figsize=(7, 3))
axes.plot(days, tpm, marker=".")
axes.xaxis.set_major_formatter(mdates.DateFormatter("%d %b"))
axes.xaxis.set_major_locator(mdates.DayLocator(interval=2))
figure.autofmt_xdate()
figure.savefig("dates.png")

How it works

1. Pass datetimes straight to plot.
2. DateFormatter controls the tick labels.
3. autofmt_xdate rotates them so they fit.

Keywords and builtins used here

• as
• for
• range

The run, in numbers

Lines

17

Characters to type

527

Tokens

155

Three-star pace

110 tpm

At the three-star pace of 110 tokens a minute, this run takes about 85 seconds.

Type this snippet

Step 3 of 4 in Reading the plot, step 12 of 14 in Plotting with matplotlib.

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