Matplotlib, Release 3.0.0
Artist
Basically everything you can see on the gure is an artist (even the Figure, Axes, and Axis
objects). This includes Text objects, Line2D objects, collection objects, Patch objects ... (you
get the idea). When the gure is rendered, all of the artists are drawn to the canvas. Most
Artists are tied to an Axes; such an Artist cannot be shared by multiple Axes, or moved from
one to another.
Types of inputs to plotting functions
All of plotting functions expect np.array or np.ma.masked_array as input. Classes that are
’array-like’ such as pandas data objects and np.matrix may or may not work as intended. It is
best to convert these to np.array objects prior to plotting.
For example, to convert a pandas.DataFrame
a = pandas.DataFrame(np.random.rand(4,5), columns = list('abcde'))
a_asndarray
= a.values
and to covert a np.matrix
b = np.matrix([[1,2],[3,4]])
b_asarray = np.asarray(b)
Matplotlib, pyplot and pylab: how are they related?
Matplotlib is the whole package; matplotlib.pyplot is a module in matplotlib; and pylab is a
module that gets installed alongside matplotlib.
Pyplot provides the state-machine interface to the underlying object-oriented plotting library.
The state-machine implicitly and automatically creates gures and axes to achieve the desired
plot. For example:
x = np.linspace(0, 2, 100)
plt.plot(x, x, label='linear')
plt.plot(x, x**2, label='quadratic')
plt.plot(x, x**3, label='cubic')
plt.xlabel('x label')
plt.ylabel('y label')
plt.title("Simple Plot")
plt.legend()
plt.show()
14 Chapter 2. Tutorials
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