recno_idx = slice(0,10)
client_idx = slice(10, 11)
volume_idx = slice(11,11+10)
order_type_idx = slice(11+10, 11+10+3)
.
!? That seems to me confusingly far from a working solution,
at least in comparison to
recno_idex = the_line[0:10]
client_idx = the_line[10:11]
...
What am I missing?
The "11+10" and "11+10+3" are to help show where the magic
numbers come from...that they're column-offsets from the previous
position...I suppose to have been consistent, I should have used
client_idx = the_line[10:10+1]
Somewhat like a kludgy version of George Sakkis's more elegant
version of slicing, but with the advantage of associating names
with the slice-boundaries.
It would be possible to write it as something like
for line in file('in.txt'):
out.write(','.join([
line[0:10], # recno
line[10:11], # client
line[11:21], # volume
line[21:24], # order
line[24:], # remainder
]))
but it's harder to verify that the slicing doesn't incur a
fence-posting error, and makes it harder to follow if
manipulations need further checking like
if line[client_idx] == 'F': continue # skip this client
There are a number of ways to slice & dice the line. I recommend
whichever is easiest to read/understand.
-tkc
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