Python Matplotlib: Splitting one Large Graph into several Sub-Graphs (Subplot)

Question

Simply put suppose I have 2 lists:
A -> Has the list of names ['A','B','C','D','E','F','G','H']
B -> Has the list of values [5,7,3,8,2,9,1,3]
A will be the names of the X-Axis labels and the corresponding values in B will be the height of the graph ( i.e. the Y-Axis ).

%matplotlib inline
import pandas as pd
from matplotlib import rcParams
import matplotlib.pyplot as plt
from operator import itemgetter

rcParams.update({'figure.autolayout': True})
plt.figure(figsize=(14,9), dpi=600)

reso_names = ['A','B','C','D','E','F','G','H']
reso_values = [5,7,3,8,2,9,1,3]
plt.bar(range(len(reso_values)), reso_values, align='center')
plt.xticks(range(len(reso_names)), list(reso_names), rotation='vertical')

plt.margins(0.075)
plt.xlabel('X-Axis')
plt.ylabel('Y-Axis')
plt.title('Graph', {'family' : 'Arial Black',
        'weight' : 'bold',
        'size'   : 22})
plt.show()

This code gives the following output :

However I want it such that it makes subgraphs for every 2 values. In this case there should be 4 subgraphs:

1st Graph has 'A' and 'B'
2nd Graph has 'C' and 'D'
3rd Graph has 'E' and 'F'
4th Graph has 'G' and 'H'

This splitting should be done dynamically (not 4 different loops, it should break the graph into units of 2 each depending on the size of the input, if list A has 10 values then it should give 5 subgraphs).

I figured out how to split the graph into two with half each but I need to achieve it using steps of N per graph (N in this example being 2).
The code I have for breaking the graph into 2 equal subgraphs is :

%matplotlib inline
import pandas as pd
from matplotlib import rcParams
import matplotlib.pyplot as plt
from operator import itemgetter

rcParams.update({'figure.autolayout': True})
plt.figure(figsize=(14,9), dpi=600)

reso_names = ['A','B','C','D','E','F','G','H']
reso_values = [5,7,3,8,2,9,1,3]

fig, axs = plt.subplots(nrows=2, sharey=True, figsize=(14,18), dpi=50)
size = int(len(reso_values))
half = int( size/2 )

fig.suptitle('Graph', 
          **{'family': 'Arial Black', 'size': 22, 'weight': 'bold'})

for ax, start, end in zip(axs, (0, half), (half, size)):
    names, values = list(reso_names[start:end]), reso_values[start:end]
    ax.bar(range(len(values)), values, align='center')
    ax.set_xlabel('X-Axis')
    ax.set_ylabel('Y-Axis')
    ax.set_xticks(range(len(names)))
    ax.set_xticklabels(names, rotation='vertical')
    ax.set_xlim(0, len(names))
fig.subplots_adjust(bottom=0.05, top=0.95)
plt.show()

Which gives me :

I just want the program to dynamically split the graphs into subgraphs based on the splitting number N.

It's difficult to get a sense of what you have and what want from your description and a code that relies on externes data. Can you post a representation of what it looks like now and what the result would look like ? — Yann
– Yann, Commented Aug 2, 2015 at 10:45
Basically I have 150 values, so I wanted to make it such that there are subgraphs each showing 30 at a time. Graph one has 0-29, the next one has 30-59 and so on. As opposed to all 150 values being crammed into one unreadable graph. — Meghdeep Ray
– Meghdeep Ray, Commented Aug 2, 2015 at 10:56

Yann · Accepted Answer · 2015-08-02 11:46:34Z

You can directly split your lists values/names with size elements into size//N + 1 list of N elements with this code :

N=3
sublists_names = [reso_names[x:x+N] for x in range(0, len(reso_names), N)]
sublists_values = [reso_values[x:x+N] for x in range(0, len(reso_values), N)]

Note that the last sublist will have less elements if N does not divide size.

Then you just perform a zip and plot each sublist in a different graph :

import pandas as pd
from matplotlib import rcParams
import matplotlib.pyplot as plt
from operator import itemgetter

rcParams.update({'figure.autolayout': True})
plt.figure(figsize=(14,9), dpi=600)

reso_names = ['A','B','C','D','E','F','G','H']
reso_values = [5,7,3,8,2,9,1,3]

N=3
sublists_names = [reso_names[x:x+N] for x in range(0, len(reso_names), N)]
sublists_values = [reso_values[x:x+N] for x in range(0, len(reso_values), N)]

size = int(len(reso_values))
fig, axs = plt.subplots(nrows=size//N+1, sharey=True, figsize=(14,18), dpi=50)

fig.suptitle('Graph', 
          **{'family': 'Arial Black', 'size': 22, 'weight': 'bold'})

for ax, names, values in zip(axs, sublists_names, sublists_values):
    ax.bar(range(len(values)), values, align='center')
    ax.set_xlabel('X-Axis')
    ax.set_ylabel('Y-Axis')
    ax.set_xticks(range(len(names)))
    ax.set_xticklabels(names, rotation='vertical')
    ax.set_xlim(0, len(names))
    #ax.set_xlim(0, N)

fig.subplots_adjust(bottom=0.05, top=0.95)
plt.show()

If the list are not dividible by N, you can uncomment the last commented line so the bars stay alined on the last subplot : (ax.set_xlim(0, N)) :

I tried to tailor this script for my problem but I have some problem. I want line plot not bar plot and how can I achieve this? #Yann can you give me suggestion?

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