Creating a list in python using os.popen

问题

Previously, I have been able to create lists using a command similar to the following:

os.popen('ls *.fits > samplelist')

Now I'm attempting to organize the files into lists by grouping them by number.

The files are named as following:

Name_0000_J.fits, Name_0001_J.fits, Name_0002_J.fits, ect.

I've attempted to run this line of code but it just creates the list skylist_J_1 and leaves it empty.

os.popen('for num in {0000..0089} ; do ls Name_$num\_J.fits >> skylist_J_1 ; done')

I ran the above in a command line and it works perfectly. Any insight would be greatly appreciated.

Edit:

I have come up with this solution but it is rather bulky. Hopefully there is a cleaner way to accomplish this.

def MkSkylist(qmin,qmax,name,band,quadrant):

    a = qmax-qmin+1

    ran = np.arange(qmin,qmax+1)
    num = [0]*a

    i = 0
    while i < a:
        num[i] = np.array2string(ran[i]).zfill(4)
        i = i + 1    

    os.popen('ls '+name+num[0]+'_'+band+'.fits > skylist_'+band+'_'+quadrant)

    i = 1
    while i < a:
        os.popen('ls '+name+num[0]+'_'+band+'.fits >> skylist_'+band+'_'+quadrant)
        i = i + 1

回答1:

The problem seems to be with the syntax of the for loop: even though that syntax is valid in bash, it seems Python doesn't like it. Not even with subprocess.Popen(..., shell=True).

So, try using seq instead:

os.popen("for num in $(seq 0 89); do printf "Name_%04dJ.fits\n" $num >> skylist_J_1; done");

Which generates a file skylist_J_1 with this content:

Name_0001J.fits
Name_0002J.fits
Name_0003J.fits
Name_0004J.fits
...
Name_0086J.fits
Name_0087J.fits
Name_0088J.fits
Name_0089J.fits

Also notice you can put the file redirection outside, which is more similar to your first example (using > instead of >>):

os.popen('for num in $(seq 0 89); do printf "Name_%04dJ.fits\n" $num; done > skylist_J_1')

来源：https://stackoverflow.com/questions/59621752/creating-a-list-in-python-using-os-popen

标签

python

popen