Split string and write to new file

[turnerca902]

Hi everyone,

I have a fairly simple problem, but having not used python in awhile, I just can't seem to get things working.
Basically, I have a text file with a number of comma separated fields (attached).
What I want to do is split the string, and extract the "File" item from each line. I then need to write this to a new file. (I also want to skip the first line.)

So my desired output file would just have:
2008308_017_079.tif
2008308_017_080.tif
2008308_017_081.tif
etc...

If anyone out there could help me with this, I'd be very grateful!

[TrustyTony]

Quite simple with the code snippet I posted today, only add removing of quoting.

# text based data input with data accessible
# with named fields or indexing
from __future__ import print_function ## Python 3 style printing
from collections import namedtuple
import string

filein = open("cb2.txt")
quotes = '\'\"'
datadict = {}

headerline = filein.readline().lower() ## lowercase field names Python style
## first non-letter and non-number is taken to be the separator
separator = headerline.strip(string.lowercase + string.digits + quotes)[0]
print("Separator is '%s'" % separator)

headerline = [field.strip(string.whitespace + quotes) for field in headerline.split(separator)]
Dataline = namedtuple('Dataline',headerline)
print ('Fields are:',Dataline._fields,'\n')

for data in filein:
    data = [f.strip(string.whitespace + quotes) for f in data.split(separator)]
    d = Dataline(*data)
    datadict[d.id] = d ## do hash of id values for fast lookup (key field)

for id in  datadict.keys():
    print(datadict[id].file)

input('Ready') ## let the output be seen when run directly

[snippsat]

One soultion with regular expression,not hard to wirte regex for this just a couple of min.

import re

text = '''\
"Id","File","Easting","Northing","Alt","Omega","Phi","Kappa","Photo","Roll","Line","Roll_line","Orient","Camera"
1800,2008308_017_079.tif,530658.110,5005704.180,2031.100000,0.351440,-0.053710,0.086470,79,2008308,17,308_17,rightX,Jen73900229d
1801,2008308_017_080.tif,531793.060,5005709.230,2033.170000,0.385000,-0.044790,-0.057690,80,2008308,17,308_17,rightX,Jen73900229d
1802,2008308_017_081.tif,532930.810,5005709.150,2032.250000,0.350180,-0.044950,0.271100,81,2008308,17,308_17,rightX,Jen73900229d
1803,2008308_017_082.tif,534066.230,5005706.620,2037.630000,0.345480,-0.036860,0.234700,82,2008308,17,308_17,rightX,Jen73900229d
1804,2008308_017_083.tif,535212.280,5005706.990,2037.470000,0.336650,-0.045540,0.306690,83,2008308,17,308_17,rightX,Jen73900229d
'''

test_match = re.findall(r'\d{7}\_\d{3}\_\d{3}\.\btif\b',text)
print test_match #Give us a list

#Looping over item in list
for item in test_match:
    print item

'''-->Out
['2008308_017_079.tif', '2008308_017_080.tif', '2008308_017_081.tif', '2008308_017_082.tif', '2008308_017_083.tif']
2008308_017_079.tif
2008308_017_080.tif
2008308_017_081.tif
2008308_017_082.tif
2008308_017_083.tif
'''

[TrustyTony]

For simple, inflexible solution you can do only:

filein = open("cb2.txt")
filein.readline() # drop first line
for line in filein:
    print line.split(',')[1]

[turnerca902]

Thanks tonyjv and Snippsat,

Your suggestions helped me get back on track.

filein = open("cb2.txt")
filein.readline()

for line in filein:
    namedata = []
    namedata = line.split(",")[1]
    print namedata + "\n"
    fileout = open("copyimg.txt" , "a")
    fileout.write(namedata + "\n")
    fileout.close()

[TrustyTony]

it is better though to move line 8 out of loop to line 3 with less indent. Then also mode 'w' is ok instead of 'a'. Of course closing must do after loop not inside (one indent less)

[turnerca902]

Thanks again tonyjv!
I'll make those changes.

[TrustyTony]

Also print is providing the newline automatically, if you prefer you can use it also to file like this:

filein = open("cb2.txt")
filein.readline()
fileout = open("copyimg.txt" , "w")

for line in filein:
    namedata = []
    namedata = line.split(",")[1]
    print namedata
    print >>fileout,namedata

fileout.close()

[turnerca902]

Oh, terrific!
I didn't know that was an option with "print". I know I'll use that method again in the future.
Many thanks for the great help and advice :)