Brett Longworth wrote:
> Hello,
>
> Today I wrote a quick script to replace elements in multiple lines of a
> file with corresponding elements from a single line in another file,
> linking the two via an index element. The code iterates through the
> entire source file to find the matching index for each line of the
> destination file. This works, but it's clearly a terrible way to solve
> the problem. Can someone point me to a more efficient, pythonic solution?
>
> thanks,
> -Brett
>
> Code:
>
> wheel = "A794"
> wheelfile = "A794.txt"
> statusfile = "CURRENT.ams"
>
> sfile = csv.reader(open(statusfile), delimiter='\t')
> statusWriter = csv.writer(open('statustest.txt', 'wb'), delimiter='\t',
> quotechar='|', quoting=csv.QUOTE_MINIMAL)
>
> for sline in sfile:
> #print sline
> wfile = csv.reader(open(wheelfile))
> for line in wfile:
> #print line[0]
> #print sline[18]
> if line[0] == sline[18]:
> sline[0] = line [1]
> sline[1] = "OSG"+str(line[4])
> sline[17] = wheel
> sline[21] = line[9]
> statusWriter.writerow(sline)
You could put the data from wheelfile into a dictionary with the first
column as the key, something like
import csv
from contextlib import contextmanager
from functools import partial
@contextmanager
def manager(mode, process, filename, **kw):
with open(filename, mode) as f:
yield process(f, **kw)
reader = partial(manager, "rb", csv.reader)
writer = partial(manager, "wb", csv.writer)
wheel = "A794"
wheelfilename = "A794.txt"
statusfilename = "CURRENT.ams"
wheel_lookup = {}
with reader(wheelfilename) as rows:
for row in rows:
key = row[0]
if key in wheel_lookup:
raise ValueError("duplicate key {}".format(key))
lookup[key] = row
with reader(statusfilename, delimiter="\t") as status_rows:
with writer("statustest.txt", delimiter="\t") as dest:
for status_row in status_rows:
key = status_row[18]
if key in lookup:
wheel_row = wheel_lookup[key]
status_row[0] = wheel_row[1]
status_row[1] = "OSG{}".format(wheel_row[4])
status_row[17] = wheel
status_row[21] = wheel_row[9]
dest.writerow(status_row)
I hope I didn't confuse the files or columns...
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