How to create a heatmap in Python with 3 columns – the x and y coordinates and the heat

Question

I have a dataframe with 3 columns, x-points, y-points and the heat. Like this:

X, Y, Z
-2, 0, 1
-2, 1, 2
-2, 2, 5
-1, 0, 3
-1, 1, 5
-1, 2, 8
.., .., ..
2, 1, 4
2, 2, 1

I want to plot a heatmap of this data with X and Y being the coords, and Z being the heat.

I have tried lots of ways to do this and constantly run into different errors.

Asked By: physicist1911

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Source

Answer 1

Use pivot and seaborn.heatmap:

import seaborn as sns

sns.heatmap(df.pivot(index='Y', columns='X', values='Z'))

Output:

IF you want to handle missing coordinates:

df2 = (df
   .pivot(index='Y', columns='X', values='Z')
   .pipe(lambda d: d.reindex(index=range(d.index.min(), d.index.max()+1),
                             columns=range(d.columns.min(), d.columns.max()+1),
                            )
        )
)

sns.heatmap(df2)

Output:

Answered By: mozway

Answer 2

https://seaborn.pydata.org/generated/seaborn.heatmap.html

However I notice your data are all numeric. You may be looking for a Z dimensional colored scatterplot rather than a true ‘heatmap’. You can use the plt.scatter function of matplotlib. (X_col=x,Y_col=y,color=Z). https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.scatter.html

Answered By: Patrick Wickham

How to create a heatmap in Python with 3 columns – the x and y coordinates and the heat

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