Re: [Matplotlib-users] creating graphs and putting them in a figure afterwards

[Benjamin R. <ben...@ou...>]

On Wed, Oct 27, 2010 at 11:08 AM, Bram Sanders <sa...@kn...> wrote:

>
> Hi,
>
> I want to create graphs, fully specify their properties and only then
> combine them in a single figure. The figure instance holding these
> graphs is made after creating the graphs: I want to decide afterwards
> what selection of graphs (subplots) to combine in my final figure.
>
> I have plotting functions for creating graphs. What should they return?
> An axes instance, figure instance ....? How to combine them in a single
> figure?
>
> I've tried adding an axes instance to a figure using fig.set_axes()
>
> Bram
>
>
Bram,

My usual practice is to have my plotting functions take an axes object and
operate on that.  So, my code looks something like this:

import matplotlib.pyplot as plt
import numpy as np

def plotfoo(X, Y1, Y2, ax) :
    ax.plot(X, Y1)
    ax.scatter(X, Y2)

X = np.linspace(1.0, 8.5, 35)
Y1, Y2 = np.random.random((2, 35))

fig = plt.figure()
ax = fig.add_subplot(111)

plotfoo(X, Y1, Y2, ax)
ax.set_title("FooBar")
ax.set_ylabel("Bar")
ax.set_xlabel("Foo")

plt.show()


Therefore, the actual process of creating the plot is separated from any
organizational/arrangement aspects and can be easily reused and mixed for
other purposes.  Imagine having multiple plotting functions and just passing
the same axes object into them to have all of them placed on the same plot.

I should note that it is easy to fall into the trap of setting graph labels
in the same function where you are plotting.  I have found this practice to
be detrimental because often times, you want to have a different title or
label for different purposes (or change the font size or whatever).  It is
just easier to keep them separate.

Of course, this isn't the only style, and I am sure others have different
approaches, but this has worked well for me the past couple of years.

I hope this is helpful!
Ben Root