FAQ: Line Graphs in Matplotlib - Figures

This community-built FAQ covers the “Figures” exercise from the lesson “Line Graphs in Matplotlib”.

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This exercise can be found in the following Codecademy content:

Data Science

Data Visualization in Python

FAQs on the exercise Figures

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Why does Python use inches (used in only three countries) ? Can it use centimetres (used in the 192 countries)?

That’s not necessarily Python but the 3rd party Matplotlib library. I’m not aware of any built-in method (at least not since I last checked) of using cm instead of inches and I can’t see it happening since it’d likely cause problems with code behaving differently on different machines. If you have a pressing need to size figures in cm you might have to write a quick function or something along those lines to convert the two.

I have 3 questions. Hope someone could help me. :pray:
①Why only the latter figure is shown when I call plt.show()? What happened to the first figure?
②What is plt.close('all') for?
③Why do I need to call plt.figure() before plt.plot() and if I reverse the order, no figure will be displayed?

import codecademylib
from matplotlib import pyplot as plt

word_length = [8, 11, 12, 11, 13, 12, 9, 9, 7, 9]
power_generated = [753.9, 768.8, 780.1, 763.7, 788.5, 782, 787.2, 806.4, 806.2, 798.9]
years = [2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009]

plt.close('all')
plt.plot(years, word_length)
plt.savefig('winning_word_lengths.png')


plt.figure(figsize=(7,3))
plt.plot(years, power_generated)
plt.savefig('power_generated.png')

plt.show()

Thanks in advance

Hi there,

When I run this code I get the 2 graphs but I dont get the green tick?

import codecademylib
from matplotlib import pyplot as plt

word_length = [8, 11, 12, 11, 13, 12, 9, 9, 7, 9]
power_generated = [753.9, 768.8, 780.1, 763.7, 788.5, 782, 787.2, 806.4, 806.2, 798.9]
years = [2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009]


plt.close('all')

plt.subplot(2,1,1)
plt.plot(years, word_length)
plt.savefig('tall_and_narrow.png')
plt.subplot(2,1,2)
plt.plot(years, power_generated)
plt.show()
plt.savefig('power_generated.png')

Id forgotten to add:

plt.figure(figsize=(7,3))

I’m confused on why it is not in pixels… This makes me think that this is then intended for printing purposes