How to set the physical size of plotnine png file

Question

I am using python’s plotnine package to create a series of plots. Often I need the plots to fit into a space x-cms by y-cms. I can control the size of the plot via:

p.save(filename=path+'fig1.png', height=10, width=12, units = 'cm', dpi=300)

But this sets the size of the plot area, whereas I need to set the size of the .png file (inclusive of titles, axis labels and legends.

That is, consider the following three plots. When inserted into a document, fig1, fig2, fig3 will take up a different amount of space in the document, necessitating some scaling. This scales other aspects of the plot such as font size.

import pandas as pd
from plotnine import *
from plotnine.data import mpg
    
path = 'C:\Users\BRB\'
    
p = (ggplot(mpg, aes(x='displ', y='hwy', colour='factor(cyl)'))
  + geom_point()
)
p.save(filename=path+'fig1.png', height=10, width=12, units = 'cm', dpi=300)

p = (ggplot(mpg, aes(x='displ', y='hwy', colour='factor(cyl)'))
  + geom_point()
  + labs(x=None,y=None)
)
p.save(filename=path+'fig2.png', height=10, width=12, units = 'cm', dpi=300)

p = (ggplot(mpg, aes( x='displ', y='hwy', colour='factor(cyl)'))
  + geom_point()
  + labs(x=None,y=None)
  + scale_color_discrete(guide=False)
)
p.save(filename=path+'fig3.png', height=10, width=12, units = 'cm', dpi=300)

How can I fix the physical size of the whole png in plotnine? And are the dimensions in the save statement only approximate? When inserted into a Word document, the first figure is 9.22cms tall and the other 2 are 8.69cms (rather than 10) and the third figure is 10.47cms wide (rather than 12).

Asked By: brb

||

Source

Answer 1

Regarding your second question, unfortunatly it is not possible to create an exact image with a exact size, as stated in this github issue.

Regarding your first question, what you could do is save the plot as a vector image (svg) and then (programatically) resize/move the img or the individual layers.

I hope this helps, it is unfortunatly one of the shortcomings of plotnine.

Answered By: Cloudkollektiv

Answer 2

I had a similar problem and I found a workaround converting the figure to matplotlib, then setting the size and then saving it:

p = (ggplot(mpg, aes(x='displ', y='hwy', colour='factor(cyl)'))
        + geom_point()
    )
fig = p.draw()
fig.set_size_inches(6.5, 3)
plt.savefig(path+'fig1.png')

Answered By: Germán Mandrini

How to set the physical size of plotnine png file

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