How make four subplots into one figure with four different protein sequences? - matplotlib

Question

How do I make four subplots into one figure and save it to my desktop? I'm having trouble with the input prompt where you can insert 4 different are protein sequences
import numpy as np
from matplotlib import pyplot as plt
protein_input = input('Protein Sequence: ')
protein_nospace = protein_input.strip()
# plot protein frequency and print graph
x_values = ['A', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'K', 'L', 'M', 'N', 'P', 'Q', 'R', 'S', 'T', 'V', 'W', 'Y']
counts = defaultdict(int)
for aa in protein_nospace:
if aa in x_values:
counts[aa] += 1
else:
counts[aa] = 1
y_values = np.array([v for v in counts.values()])
plt.figure()
plt.bar(x_values, y_values)
plt.title('Amino acid Frequencies')
plt.xlabel('Amino Acids')
plt.ylabel('Frequency')
plt.show()

Answer 1

You could create a subplot for each of the proteins. Matplotlib object-oriented interface helps to write everything into its subplot. plt.savefig saves the plot to a file.
In general, it is not a good idea to read this type of input with an interactive session. That way, you can't easily check for errors, nor can you easily reference the input later to verify how the plot was created.
For short scripts and short inputs, the easiest is to just copy-paste your input into the code. And then save the code for later reference. For longer inputs, or to have the same graph with other input sets, you can save only the strings in separate files.
The code below now shows how the input can be read interactively. (In the comment there is a version with "hard-coded" inputs.)
from matplotlib import pyplot as plt
from collections import defaultdict
protein_input_list = []
while True:
protein_input = input('Enter next Protein Sequences (empty input to stop):')
protein_nospace = protein_input.strip()
if len(protein_nospace) == 0:
break
else:
protein_input_list.append(protein_nospace)
'''
protein_input_list = ['ABABDEADWDSWEFAECD',
'DEFSDMDSLHEWVOIHWEAAEHRG',
'HIWEORMLSDAWEEFWEFWEEWJK',
'JLSSFSFLIWIJOWHOE']
'''
fig, axes = plt.subplots(ncols=len(protein_input_list), figsize=(15, 5))
for index, ( ax, protein_nospace) in enumerate( zip(axes.ravel(), protein_input_list)):
x_values = ['A', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'K', 'L', 'M', 'N', 'P', 'Q', 'R', 'S', 'T', 'V', 'W', 'Y']
counts = defaultdict(int)
for aa in protein_nospace:
if aa in x_values:
counts[aa] += 1
else:
counts[aa] = 1
ax.bar(counts.keys(), counts.values())
ax.set_title(f'Amino acid Frequencies {index+1}')
ax.set_xlabel('Amino Acids')
ax.set_ylabel('Frequency')
plt.savefig('Amino acid Frequencies.png')
plt.show()