Peter Otten wrote:
> validationma...@gmail.com wrote:
>
>> i have a code in python to search and replace what i need though is to
>> replace the first say 10 instances of the number 1 with 2 and the second
>> 10 instances with the number 3. anybody knows how to do that?
>>
>> fin = open(r'F:\1\xxx.txt')
>> fout = open(r'F:\1\xxx2.txt', "wt")
>> for line in fin:
>> fout.write( line.replace('1', '2') )
>> fin.close()
>> fout.close()
>
> If the search token can occur more than once in a line you cannot use
> str.replace(). Here's a solution without regular expressions. I
> implemented the "repeat something" and the "replace token with something
> different every time" separately.
>
> $ cat replace_increasing.py
> #!/usr/bin/env python3
Should also work with python2 once you add
try:
from future_builtins import zip, map
except ImportError:
pass
to make map() lazy.
> from itertools import chain, count, repeat
Lest you die of an itertools overdose here's a slightly simpler version:
#!/usr/bin/env python3
def numberstrings(repeat, start=1):
"""
>>> [v for i, v in zip(range(10), numberstrings(3, 1))]
['1', '1', '1', '2', '2', '2', '3', '3', '3', '4']
"""
value = start
while True:
for _i in range(repeat):
yield str(value)
value += 1
def make_replace(token, replace):
"""
>>> r = make_replace("x", "ABCDEFGH")
>>> r("onextwoxthreex")
'oneAtwoBthreeC'
>>> r("no match")
'no match'
>>> r("x at start")
'D at start'
>>> r("somexsomewhere")
'someEsomewhere'
>>> r("xxx")
'FGH'
>>> try: r("x")
... except StopIteration: "OK"
'OK'
"""
replaceiter = iter(replace)
def replace(line):
parts = line.split(token)
return "".join(
[p + next(replaceiter) for p in parts[:-1]]
+ parts[-1:]
)
return replace
def main():
import argparse
parser = argparse.ArgumentParser()
parser.add_argument("infile")
parser.add_argument("outfile")
parser.add_argument("token")
parser.add_argument("-r", "--repeat", type=int, default=10)
args = parser.parse_args()
replace = make_replace(args.token, numberstrings(args.repeat))
with open(args.infile) as instream:
with open(args.outfile, "w") as outstream:
outstream.writelines(replace(line) for line in instream)
if __name__ == "__main__":
main()
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