Combining Matplotlib and Pandas

The matplotlib framework integrates well with the popular pandas data processing library.

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For the following examples we will use our usual data:

months = [
    "Jan", "Feb", "Mar", "Apr", "May", "Jun",
    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
]

water_levels_2010 = [
    5.77, 6.04, 6.52, 6.48, 6.54, 5.92, 
    5.64, 5.21, 5.01, 5.18, 5.45, 5.59
]

water_levels_2020 = [
    5.48, 5.82, 6.31, 6.26, 6.09, 5.87, 
    5.72, 5.54, 5.22, 4.86, 5.12, 5.40
]

Plotting Pandas Series

To plot a pandas series, it can be directly fed into the pyplot.plot(…)-function.

from matplotlib import pyplot
from pandas import Series

# … Raw data as above

# We turn it into a series
measurements = Series(
    data = water_levels_2010,
    index=months,
    name="Water levels in 2010"
)

# And plot it
pyplot.plot(measurements, label=measurements.name)  # (1)
pyplot.legend()
pyplot.show()

Explanation

1. Note how we can make use of the fact that the series has a name to also assign it as a plot label.

Working with DataFrames

Matplotlib can also handle pandas DataFrames as input:

from pandas import DataFrame
from matplotlib import pyplot

# … Raw data as above

measurements = DataFrame(
    data = {
        "Water levels in 2010": water_levels_2010,
        "Water levels in 2020": water_levels_2020
    },
    index = months
)

pyplot.plot(measurements)
pyplot.legend(measurements.columns.values)
pyplot.show()

Data frames in pandas actually also bring a plotting function with them, so you could also write it this way:

# … Import and data frame creation as before

measurements.plot()
pyplot.show()

Isn’t that convenient? You can find more information on the DataFrame.plot documentation page