How do I use regex to find multiple matches in the same string?-CodePudding

I am trying to use regex to extract data from a csv file with the following format

 2022-May-02 00:52:59.773,*,m, 22 57 44.81, -08 18 03.1,    0.835,  4.256,  1.62295918340127, -9.6380650,   58.8566,/L,   38.0538,   1.8729490,  67.895361,  -14.70063,         n.a.,    n.a.,
 2022-May-02 00:57:59.773,*,m, 22 57 45.40, -08 17 59.6,    0.836,  4.257,  1.62293986289045, -9.6316459,   58.8574,/L,   38.0543,   1.8732214,  67.896937,  -14.68939,         n.a.,    n.a.,
 2022-May-02 01:02:59.773,*,m, 22 57 45.98, -08 17 56.0,    0.838,  4.258,  1.62292055513269, -9.6253460,   58.8581,/L,   38.0547,   1.8735000,  67.898620,  -14.67828,         n.a.,    n.a.

From this, I want to extract the following groups (columns 1, 4 and 5)

2022-May-02 00:52:59.773, 22, 57, 44.81, -08, 18, 03.1 
2022-May-02 00:57:59.773, 22, 57, 45.40, -08, 17, 59.6
2022-May-02 01:02:59.773, 22, 57, 45.98, -08, 17, 56.0

The pattern I am currently using is pattern = "^\s?([^,] ),[^,] ,[^,] , (\-*\d ) (\d ) (\d \.\d ), (\-*\d ) (\d ) (\d \.\d )"

and re.match(pattern, table, flags=re.MULTILINE)

From this, I only get a match with the first line of the csv file.

print(results.groups()) 
>> ('2022-May-02 01:46:35.916', '22', '57', '44.81', '-08', '18', '03.1')

What do I need to do to match the same pattern on multiple lines?

CodePudding user response：

Since you are using CSV file, don't use REGEX, instead use the inbuildcsv library, with it you will be able to extract any column with ease.

import csv

with open('csv_file.csv', 'r') as input:
    input_reader = csv.reader(input)
    for line in input_reader:
        print(line[0], line[3], line[4])

#2022-May-02 00:52:59.773, 22 57 44.81, -08 18 03.1 
#2022-May-02 00:57:59.773, 22 57 45.40, -08 17 59.6
#2022-May-02 01:02:59.773, 22 57 45.98, -08 17 56.0

CodePudding user response：

You would be best to avoid a regular expression and use Python's CSV library. The last 6 values you want are inside columns 4 and 5 separated by spaces. So you will need to split those out separately. For example:

import csv

with open('input.csv') as f_input, open('output.csv', 'w', newline='') as f_output:
    csv_input = csv.reader(f_input, skipinitialspace=True)
    csv_output = csv.writer(f_output)
    
    for row in csv_input:
        csv_output.writerow([row[0], *row[3].split(' '), *row[4].split(' ')])

This would create an output.csv file containing:

2022-May-02 00:52:59.773,22,57,44.81,-08,18,03.1
2022-May-02 00:57:59.773,22,57,45.40,-08,17,59.6
2022-May-02 01:02:59.773,22,57,45.98,-08,17,56.0