mk wrote:
John Filben wrote:
I am new to Python but have used many other (mostly dead) languages in
the past. I want to be able to process *.txt and *.csv files. I can
now read that and then change them as needed – mostly just take a
column and do some if-then to create a new variable. My problem is
sorting these files:
1.) How do I sort file1.txt by position and write out
file1_sorted.txt; for example, if all the records are 100 bytes long
and there is a three digit id in the position 0-2; here would be some
sample data:
a. 001JohnFilben……
b. 002Joe Smith…..
Use a dictionary:
linedict = {}
for line in f:
key = line[:3]
linedict[key] = line[3:] # or alternatively 'line' if you want to
include key in the line anyway
sortedlines = []
for key in linedict.keys().sort():
sortedlines.append(linedict[key])
(untested)
This is the simplest, and probably inefficient approach. But it should
work.
[snip]
Simpler would be:
lines = f.readlines()
lines.sort(key=lambda line: line[ : 3])
or even:
lines = sorted(f.readlines(), key=lambda line: line[ : 3]))
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