strip part of string

[Francesco Pietra]

Hi:
I would like to delete everything from column 54 on for each line
beginning with "ATOM". In the example in the attachment (sorry for the
attachment; I found no way with Google mail to have plain text mail)
the new line would become:

ATOM 49 NH1 ARG 84 84.628 41.570 44.395

without any blank space to the right. . Everything else should remain
at its original column. I have been looking for ???? statement, unable
(my big fault ) to find a right one. I tried with slices % but it
becomes unnecessarily complex.


Thanks
francesco

 

[Steven D'Aprano]

Hi:
I would like to delete everything from column 54 on for each line
beginning with "ATOM". In the example in the attachment (sorry for the
attachment; I found no way with Google mail to have plain text mail) the
new line would become:

ATOM 49 NH1 ARG 84 84.628 41.570 44.395

if line.startswith("ATOM"):
line = line[0:54].rstrip()

should do what you want.

 

[John Machin]

Hi:
I would like to delete everything from column 54 on for each line
beginning with "ATOM". In the example in the attachment (sorry for the
attachment; I found no way with Google mail to have plain text mail)

Many of your audience won't have seen your quite unnecessary
attachment; you could have in-lined the text just like this:
[except that I've deleted empty lines, and chopped some irrelevant
stuff off the right hand end of some lines so that line-wrapping won't
confuse anybody any more than they are already
]

8<---
# Sample line
# 1 2 3 4 5
# 012345678901234567890123456789012345678901234567890123456789
# ATOM 49 NH1 ARG 84 84.628 41.570 44.395 0.00
data = open('rec.crg', 'r')
outp = open('rec.strip.crg', 'w')
for L in data:
if L[3] == 'M':
L = L[:55] ???????
outp.write(L)
8<---

the new line would become:

ATOM     49  NH1 ARG    84      84.628  41.570  44.395

without any blank space to the right. . Everything else should remain
at its original column. I have been looking for ???? statement, unable
(my big fault ) to find a right one. I tried with slices % but it
becomes unnecessarily complex.

You wish to retain 54 characters, but are retaining 55. You need a
newline on the end of the line. So the statement
L = L[:55]
should be
L = L[:54] + '\n'
You may wish to precede that with
assert len(L) >= 54
You may wish to change
if L[3] == 'M':
to
if L.startswith('ATOM'):
to accord with your requirements statement.

HTH,
John