Question

i have this code to produce multiple plots from all the text files in a folder. It runs perfectly fine and shows the plots but i cant work out how to then save them all.

import re
import numpy as np
import matplotlib.pyplot as plt
import pylab as pl
import os

rootdir='C:\documents\Neighbors for each search id'

for subdir,dirs,files in os.walk(rootdir):
 for file in files:
  f=open(os.path.join(subdir,file),'r')
  print file
  data=np.loadtxt(f)

  #plot data
  pl.plot(data[:,1], data[:,2], 'gs')

  #Put in the errors
  pl.errorbar(data[:,1], data[:,2], data[:,3], data[:,4], fmt='ro')

  #Dashed lines showing pmRa=0 and pmDec=0
  pl.axvline(0,linestyle='--', color='k')
  pl.axhline(0,linestyle='--', color='k')
  pl.show()

  f.close()

I have previously used

fileName="C:\documents\FirstPlot.png"
plt.savefig(fileName, format="png")

but i think this just saves each graph into one file and overwrites the last one.

Answer 1

All you have to do is provide unique filenames. You could use a counter:

fileNameTemplate = r'C:\documents\Plot{0:02d}.png'

for subdir,dirs,files in os.walk(rootdir):
    for count, file in enumerate(files):
        # Generate a plot in `pl`
        pl.savefig(fileNameTemplate.format(count), format='png')
        pl.clf()  # Clear the figure for the next loop

What I did:

• Create a template using python’s string formatting syntax

• Added a counter to the loop using the enumerate() function.

• Used the counter and the template to generate a new filename for each plot.