How to add double quotes to sequence of char inside a string-CodePudding

I have a string in Python like that one:

'speed=36.2448,course=331.35,gps_time=2021-11-22T00:43:22.678Z,fix=1,message_source=device_gps,period_km=0.436,location=Middle of no where,x=3.2'

and I need to add double quotes to non-numerical string situated between a '=' and a ','. Result should looks like this:

'speed=36.2448,course=331.35,gps_time="2021-11-22T00:43:22.678Z",fix=1,message_source="device_gps",period_km=0.436,location="Middle of no where",x=3.2'

I'm trying with regex since hours but turning crazy. Any help would be welcome. In advance thank you.

CodePudding user response：

If you don't care about handling escaped commas, you can simply split the string on commas, then split on =, handle the right side based on if it's numeric or not, and finally join everything.

s = 'speed=36.2448,course=331.35,gps_time=2021-11-22T00:43:22.678Z,fix=1,message_source=device_gps,period_km=0.436,location=Middle of no where,x=3.2'

items = []
for item in s.split(','):
    lhs, rhs = item.split('=', 1)
    try:
        float(rhs)
        # Could convert rhs to float, so leave item unchanged
        items.append(item)
    except ValueError:
        # Could not convert rhs to float, so is not numeric. Surround rhs with quotes
        items.append(f'{lhs}="{rhs}"')

modified_s = ",".join(items)

which gives

modified_s = 'speed=36.2448,course=331.35,gps_time="2021-11-22T00:43:22.678Z",fix=1,message_source="device_gps",period_km=0.436,location="Middle of no where",x=3.2'

CodePudding user response：

You might use a pattern with a capture group, and in the replacement use the capture group between double quotes.

=(?!\d (?:\.\d )?(?:,|$))([^",\n] )

Regex demo

The pattern matches:

= Match literally
(?! Negative lookahead, assert what is directly to the right is not
- \d (?:\.\d )?(?:,|$) Match 1 digits with an optional decimal part followed by either , or end of the string
) Close lookahead
( Capture group 1
- [^",\n] match 1 times any character except " , or a newline
) Close group 1

For example

import re

regex = r"=(?!\d (?:\.\d )?(?:,|$))([^\",\n] )"
s = 'speed=36.2448,course=331.35,gps_time=2021-11-22T00:43:22.678Z,fix=1,message_source=device_gps,period_km=0.436,location=Middle of no where,x=3.2'
result = re.sub(regex, r'="\1"', s)
print(result)

Output

speed=36.2448,course=331.35,gps_time="2021-11-22T00:43:22.678Z",fix=1,message_source="device_gps",period_km=0.436,location="Middle of no where",x=3.2