Simplest way to locate a string in a column and get the value on the same row in another column
Tim Chase
python.list at tim.thechases.com
Thu Apr 28 15:06:51 EDT 2016
On 2016-04-28 18:37, David Shi via Python-list wrote:
> What is the simplest way to locate a string in a column and get
> the value on the same row in another column ? 1 a2 b3 c
> Locate b and obtain 2 in a table.
> Looking forward to hearing from you.
I've had success with using regexp matches with their start/stop
location information:
s1 = "1 a2 b3 c"
s2 = "abcdefghijklmn"
import re
r = re.compile(r"a2\s*") # define the pattern you want
m = r.search(s1)
if m: # if our pattern was in the header
# take the corresponding slice out of s2
result = s2[m.start():m.end()] # 'defghi'
This also works nicely with re.finditer() as I've had
column-delimited files where each header had no spaces
EMPID FIRST_NAME LAST_NAME
123456 John Smith
234567 Ellen Miller
so I did something like
r = re.compile(r"(\S+)\s*")
with open("data.txt") as f:
headers = next(f)
header_map = dict(
(m.group(1), slice(m.start(), m.end()))
for m in r.finditer(headers)
)
for row in f:
empid = row[header_map["EMPID"]].rstrip()
fname = row[header_map["FIRST_NAME"]].rstrip()
lname = row[header_map["LAST_NAME"]].rstrip()
process(empid, fname, lname)
# or
# data = dict(
# (field, row[slc])
# for field, slc in row.items()
# )
# process(data)
Hope this gives you some helpful techniques.
-tkc
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