Customizing legends¶

This is a short tutorial showing how different arguments to the legend keyword in the pyam plotting library affects where the legend is located.

We use the scenario ensemble from the first-steps tutorial (link).

[1]:

import pyam

[2]:

df = (
    pyam.IamDataFrame(data='tutorial_data.csv')
    .filter(variable='Emissions|CO2', region='World')
)

df.head()

pyam - INFO: Running in a notebook, setting up a basic logging at level INFO
pyam.core - INFO: Reading file tutorial_data.csv

[2]:

	model	scenario	region	variable	unit	year	value
0	AIM/CGE 2.1	CD-LINKS_INDCi	World	Emissions\|CO2	Mt CO2/yr	2010	33954.0254
1	AIM/CGE 2.1	CD-LINKS_INDCi	World	Emissions\|CO2	Mt CO2/yr	2020	39274.5709
2	AIM/CGE 2.1	CD-LINKS_INDCi	World	Emissions\|CO2	Mt CO2/yr	2030	36068.4425
3	AIM/CGE 2.1	CD-LINKS_INDCi	World	Emissions\|CO2	Mt CO2/yr	2040	38447.2877
4	AIM/CGE 2.1	CD-LINKS_INDCi	World	Emissions\|CO2	Mt CO2/yr	2050	39519.9596

By default, a legend will not appear if there are too many entries.

[3]:

df.plot()

pyam.plotting - INFO: >=13 labels, not applying legend

[3]:

<AxesSubplot:title={'center':'region: World - variable: Emissions|CO2'}, xlabel='Year', ylabel='Mt CO2/yr'>

By using the color argument, we tell the pyam plotting library to apply colours by model family. This reduces the number of legend entries (from 38 model-scenario combinations to 8 model families), and the legend will be shown by default with matplotib standard settings.

[4]:

df.plot(color='model')

[4]:

<AxesSubplot:title={'center':'region: World - variable: Emissions|CO2'}, xlabel='Year', ylabel='Mt CO2/yr'>

You can use standard matplotlib legend arguments by passing a dictionary of keyword arguments.

[5]:

df.plot(color='model', legend=dict(loc='center left'))

[5]:

<AxesSubplot:title={'center':'region: World - variable: Emissions|CO2'}, xlabel='Year', ylabel='Mt CO2/yr'>

However, we also offer support for a few standard special cases, namely legends to the right of a plot and legends below the plot

[6]:

from pyam.plotting import OUTSIDE_LEGEND

[7]:

df.plot(color='model', legend=OUTSIDE_LEGEND['right'])

[7]:

<AxesSubplot:title={'center':'region: World - variable: Emissions|CO2'}, xlabel='Year', ylabel='Mt CO2/yr'>

[8]:

df.plot(color='model', legend=OUTSIDE_LEGEND['bottom'])

[8]:

<AxesSubplot:title={'center':'region: World - variable: Emissions|CO2'}, xlabel='Year', ylabel='Mt CO2/yr'>