python imprimir determinada linha

Saturday, October 31, 2009

Python - print section of file using line number

e.g. Print the section of input file 'input.txt' between line number 22 and 89.

Using python enumerate function sequence numbers:

for i,line in enumerate(open("file.txt")):
    if i >= 21 and i < 89 :
        print line,

And if you want to write the section to a new file say '/tmp/fileA'

fp = open("/tmp/fileA","w")
for i,line in enumerate(open("file.txt")):
    if i >= 21 and i < 89 :
        fp.write(line)

Another approach:

print(''.join(open('file.txt', 'r').readlines()[21:89])),

And if you wish to write the section to a new file say '/tmp/fileB'

fp = open("/tmp/fileB","w")
fp.write(''.join(open('file.txt', 'r').readlines()[21:89])),

Read about python enumerate function here and below is a small example using python enumerate function:

>>> for i, student in enumerate(['Alex', 'Ryan', 'Deb']):
...     print i, student
...
0 Alex
1 Ryan
2 Deb
>>>

Also find my other post on Extracting section of a file using line numbers applying awk, sed, Perl, vi editor and UNIX/Linux head and tail command techniques.