将函数应用于文件中每一行的特定表达式

Question

I currently am reading the contents of a file to a new file for every case instance where the lines fit a specific criteria. See the code below

from string import punctuation

fpath = open('Redshift_twb_1.txt', 'r')
lines = fpath.readlines()

fpath_write = open('Redshift_1_new.txt', 'w+')

# filter the list; with the string 'apple'
# replace 'apple' with whatever string you want to find
temp_out_lines = [line for line in lines if '<column caption' in line]
out_lines = [line for line in temp_out_lines if 'param-domain-type' not in line]

# Lambda function that maps .lower() function to every element of the list out_lines
lower_lines = map(lambda x:x.lower(), out_lines)

# Join the lines into a single string
output = '\n'.join(lower_lines)

# write it
fpath_write.write(output)

fpath.close()
fpath_write.close()

My goal is to implement functionality that can read take a line and downcase or lowercase a specific parameter before that line is then written to the new file.

Currently, the process takes in a line, checks if it matches <column caption , then checks if it does not contain param-domain-type . and if both of those pass, the line is then added to the new txt file.

An example line is below:

<column caption='Section' datatype='string' name='[SECTION]' role='dimension' type='nominal'>

The goal is to check every line before it is added to the new txt file, and for every instance of name='[****]' , make the value within the [] lowercase. currently, they are upper case.

Note: only the value within the [] 's for the param name= can be lowercased. there are other params in the line that must stay capitalized.

Thanks!

Edit: Another option would be to do a make shift find and replace that would find all instances with name='[ABC]' , and replace it with name='[abc]' . But still, I do not know how to go about this on my own.

Edit2: Upon implementing Regex, I have also used a for loop to loop through every instance of the txt file... see below code.

for x in range(len(out_lines)):
    print(out_lines[x])
    test = str(out_lines[x])
    out_lines[x] = re.sub(r"(name='([.*?])')", lambda m: m.group(1).lower(), test)
    print(out_lines[x])

However when I do so I still get the same output:

<column caption='Location' datatype='string' name='[MANAGEMENT_LOCATION]' role='dimension' type='nominal' />

<column caption='Location' datatype='string' name='[MANAGEMENT_LOCATION]' role='dimension' type='nominal' />

Answer 1

you can use re python module to replace necessary substring.

import re
re.sub(r"(name='(\[.*?\])')", lambda m: m.group(1).lower(), <YOUR TEXT>)