On 2018-06-13 18:32, Ganesh Pal wrote:
On Wed, Jun 13, 2018 at 5:59 PM, Rhodri James <rho...@kynesim.co.uk> wrote:
On 13/06/18 09:08, Ganesh Pal wrote:
Hi Team,
I wanted to parse a file and extract few feilds that are present after "="
in a text file .
Example , form the below line I need to extract the values present after
--struct =, --loc=, --size= and --log_file=
Sample input
line = '06/12/2018 11:13:23 AM python toolname.py --struct=data_block
--log_file=/var/1000111/test18.log --addr=None --loc=0 --mirror=10
--path=/tmp/data_block.txt size=8'
Did you mean "--size=8" at the end? That's what your explanation implied.
Yes James you got it right , I meant "--size=8 " .,
Hi Team,
I played further with python's re.findall() and I am able to extract all
the required fields , I have 2 further questions too , please suggest
Question 1:
Please let me know the mistakes in the below code and suggest if it can
be optimized further with better regex
# This code has to extract various the fields from a single line (
assuming the line is matched here ) of a log file that contains various
values (and then store the extracted values in a dictionary )
import re
line = '06/12/2018 11:13:23 AM python toolname.py --struct=data_block
--log_file=/var/1000111/test18.log --addr=None --loc=0 --mirror=10
--path=/tmp/data_block.txt --size=8'
#loc is an number
r_loc = r"--loc=([0-9]+)"
r_size = r'--size=([0-9]+)'
r_struct = r'--struct=([A-Za-z_]+)'
r_log_file = r'--log_file=([A-Za-z0-9_/.]+)'
Here you're searching for each match _twice_:
if re.findall(r_loc, line):
print re.findall(r_loc, line)
if re.findall(r_size, line):
print re.findall(r_size, line)
if re.findall(r_struct, line):
print re.findall(r_struct, line)
if re.findall(r_log_file, line):
print re.findall(r_log_file, line)
o/p:
root@X1:/Play_ground/SPECIAL_TYPES/REGEX# python regex_002.py
['0']
['8']
['data_block']
['/var/1000111/test18.log']
Question 2:
I tried to see if I can use re.search with look behind assertion , it
seems to work , any comments or suggestions
Example:
import re
line = '06/12/2018 11:13:23 AM python toolname.py --struct=data_block
--log_file=/var/1000111/test18.log --addr=None --loc=0 --mirror=10
--path=/tmp/data_block.txt --size=8'
match = re.search(r'(?P<loc>(?<=--loc=)([0-9]+))', line)
if match:
print match.group('loc')
o/p: root@X1:/Play_ground/SPECIAL_TYPES/REGEX# python regex_002.py
0
I want to build the sub patterns and use match.group() to get the values
, some thing as show below but it doesn't seem to work
match = re.search(r'(?P<loc>(?<=--loc=)([0-9]+))'
r'(?P<size>(?<=--size=)([0-9]+))', line)
if match:
print match.group('loc')
print match.group('size')
You can combine them into a single findall:
captures =
re.findall(r'--(loc=[0-9]+)|--(size=[0-9]+)|--(struct=[A-Za-z_]+)|--(log_file=[A-Za-z0-9_/.]+)',
line)
captures
[('', '', 'struct=data_block', ''), ('', '', '',
'log_file=/var/1000111/test18.log'), ('loc=0', '', '', ''), ('',
'size=8', '', '')]
In each tuple of the list, there's only one match, the others are empty,
so get rid of the empty ones:
[c for cap in captures for c in cap if c]
Split each of the matches on the first '=':
[c.split('=', 1) for cap in captures for c in cap if c]
For ease of use, pass the key/value pairs into dict:
info = dict(c.split('=', 1) for cap in captures for c in cap if c)
info
{'struct': 'data_block', 'log_file': '/var/1000111/test18.log', 'loc':
'0', 'size': '8'}
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