# Matplotlib tutorial

## Nicolas P. Rougier Sources are available from github

You can test your installation before the tutorial using the check-installation.py script.

Tutorial can be read at http://www.labri.fr/perso/nrougier/teaching/matplotlib/matplotlib.html

# Introduction

matplotlib is probably the single most used Python package for 2D-graphics. It provides both a very quick way to visualize data from Python and publication-quality figures in many formats. We are going to explore matplotlib in interactive mode covering most common cases.

## IPython and the pylab mode

IPython is an enhanced interactive Python shell that has lots of interesting features including named inputs and outputs, access to shell commands, improved debugging and many more. When we start it with the command line argument -pylab (--pylab since IPython version 0.12), it allows interactive matplotlib sessions that have Matlab/Mathematica-like functionality.

## pyplot

pyplot provides a convenient interface to the matplotlib object-oriented plotting library. It is modeled closely after Matlab(TM). Therefore, the majority of plotting commands in pyplot have Matlab(TM) analogs with similar arguments. Important commands are explained with interactive examples.

# Simple plot

In this section, we want to draw the cosine and sine functions on the same plot. Starting from the default settings, we'll enrich the figure step by step to make it nicer.

First step is to get the data for the sine and cosine functions:

import numpy as np

X = np.linspace(-np.pi, np.pi, 256,endpoint=True)
C,S = np.cos(X), np.sin(X)


X is now a numpy array with 256 values ranging from -π to +π (included). C is the cosine (256 values) and S is the sine (256 values).

To run the example, you can download each of the examples and run it using:

## Colormaps

All colormaps can be reversed by appending _r. For instance, gray_r is the reverse of gray.

If you want to know more about colormaps, checks Documenting the matplotlib colormaps.

### Base

Name Appearance
autumn bone cool copper flag gray hot hsv jet pink prism spectral spring summer winter ### GIST

Name Appearance
gist_earth gist_gray gist_heat gist_ncar gist_rainbow gist_stern gist_yarg ### Sequential

Name Appearance
BrBG PiYG PRGn PuOr RdBu RdGy RdYlBu RdYlGn Spectral ### Diverging

Name Appearance
Blues BuGn BuPu GnBu Greens Greys Oranges OrRd PuBu PuBuGn PuRd Purples RdPu Reds YlGn YlGnBu YlOrBr YlOrRd ### Qualitative

Name Appearance
Accent Dark2 Paired Pastel1 Pastel2 Set1 Set2 Set3 ### Miscellaneous

Name Appearance
afmhot binary brg bwr coolwarm CMRmap cubehelix gnuplot gnuplot2 ocean rainbow seismic terrain 