Maintain A4 plot size with arbitrary number of subplots

Community matplotlib-users
1

Hi,

In my script a variable number of graphs is generated. I want to place
them in one column with arbitrary number of rows onto an A4 canvas (for
pdf export).

Unfortunately the figsize directive seems to have no effect. The figure
is always 8x6 inch.

Which code do I have to use in this case?

My minimal code:

···

#######################################

import matplotlib.pyplot as plt
from matplotlib.backends.backend_pdf import PdfPages
import numpy as np

x = np.arange(10)
y = np.arange(10)

fig_width_cm = 21 # A4 page
fig_height_cm = 29.7
inches_per_cm = 1 / 2.58 # Convert cm to inches
fig_width = fig_width_cm * inches_per_cm # width in inches
fig_height = fig_height_cm * inches_per_cm # height in inches
fig_size = [fig_width, fig_height]

pdf = PdfPages('outfile.pdf')
fig = plt.figure(figsize = fig_size)
allplots = 3 # This is the variable number of subplots
f, axarr = plt.subplots(allplots, 1)

for plot in range(allplots):
    axarr[plot].plot(x+plot, y)

pdf.savefig()
pdf.close()

2

Your call to “plt.subplots” is creating a new figure object, which never gets the figsize parameter (only the old figure object has that set).

Cheers!
Ben Root

···

On Mon, Jun 25, 2012 at 1:12 PM, mogliii <mogliii@…361…> wrote:

Hi,

In my script a variable number of graphs is generated. I want to place

them in one column with arbitrary number of rows onto an A4 canvas (for

pdf export).

Unfortunately the figsize directive seems to have no effect. The figure

is always 8x6 inch.

Which code do I have to use in this case?

My minimal code:

#######################################

import matplotlib.pyplot as plt

from matplotlib.backends.backend_pdf import PdfPages

import numpy as np

x = np.arange(10)

y = np.arange(10)

fig_width_cm = 21 # A4 page

fig_height_cm = 29.7

inches_per_cm = 1 / 2.58 # Convert cm to inches

fig_width = fig_width_cm * inches_per_cm # width in inches

fig_height = fig_height_cm * inches_per_cm # height in inches

fig_size = [fig_width, fig_height]

pdf = PdfPages(‘outfile.pdf’)

fig = plt.figure(figsize = fig_size)

allplots = 3 # This is the variable number of subplots

f, axarr = plt.subplots(allplots, 1)

for plot in range(allplots):

axarr[plot].plot(x+plot, y)

pdf.savefig()

pdf.close()

3

Hi,
indeed you are right. I added "f.set_size_inches(fig_size)" and it works
Also I had a wrong conversion of inch to cm (2.58 before).

Thank you for your help,
Mogliii

The final code:

···

On 25/06/12 18:30, Benjamin Root wrote:

Your call to "plt.subplots" is creating a new figure object, which
never gets the figsize parameter (only the old figure object has that
set).

Cheers!
Ben Root

#################

import matplotlib.pyplot as plt
from matplotlib.backends.backend_pdf import PdfPages
import numpy as np

x = np.arange(10)
y = np.arange(10)

fig_width_cm = 21 # A4 page
fig_height_cm = 29.7
inches_per_cm = 1 / 2.54 # Convert cm to inches
fig_width = fig_width_cm * inches_per_cm # width in inches
fig_height = fig_height_cm * inches_per_cm # height in inches
fig_size = [fig_width, fig_height]

pdf = PdfPages('outfile.pdf')
allplots = 3 # This is the variable number of subplots
f, axarr = plt.subplots(allplots, 1)
f.set_size_inches(fig_size)

for plot in range(allplots):
    axarr[plot].plot(x + plot, y)

pdf.savefig()
pdf.close()

4

Even better:

f, axarr = plt.subplots(allplots, 1, figsize = fig_size)

Its always difficult to predict which **kwargs could/would be valid...