Question

I am new at programming in python and am in the process of trying to create a setup of processing thousands of files with one piece of code in python. I created a practice folder to do this in. In it are two FITS files (FITS1.fits and FITS2.fits). I did the following to put them both in a .txt file:

ls > practice.txt

Here is what I did next:

$ python
import numpy
import pyfits
import matplotlib.pyplot as plt
from matplotlib import pylab
from pylab import *
import asciidata

a = asciidata.open('practice.txt')

print a[0][0] #To test to see if practice.txt really contains my FITS files FITS1.fits
i = 0
while i <=1 #Now I attempt a while loop to read data from columns in FITS files, plot the numbers desired, save and show the figures. I chose i <=1 because there are only two FITS files in the text(also because of zero-indexing). 

    b = pyfits.getdata(a[0][i]) # "i" will be the index used to use a different file when the while loop gets to the end

    time = b['TIME'] #'TIME' is a column in the FITS file
    brightness = b['SAP_FLUX']
    plt.plot(time, brightness)
    xlabel('Time(days)')
    ylabel('Brightness (e-/s)')
    title(a[0][i])

    pylab.savefig('a[0][i].png') #Here am I lost on how to get the while loop to name the saved figure something different every time. It takes the 'a[0][i].png' as a string and not as the index I am trying to make it be.

    pylab.show()

    i=i+1 # I placed this here, hoping that when the while loop gets to this point, it would start over again with a different "i" value

After pressing enter twice, I see the first figure as expected. Then I will close it and see the second. However, only the first figure is saved. Does anyone have any suggestions on how I can change my loop to do what I need it to?

Answer 1

In your code the i is being treated as the letter i, not the variable. If you wanted to keep this naming you could do something like:

FileName = 'a[0][%s].png' % i
pylab.savefig(FileName)