在Python 3.x中替换字符串中的转义序列字符

Question

I have used the following code to replace the escaped characters in a string. I have first done splitting by \\n and the used re.sub() , but still I dont know what I am missing, the code is not working according to the expectations. I am a newbie at Python, so please don't judge if there are optimisation problems. Here is my code :

#import sys
import re

String = "1\r\r\t\r\n2\r\r\n3\r\r\r\r\n\r\n\r4\n\r"
splitString = String.split('\n')
replacedStrings = []
i=0

for oneString in splitString:
    #oneString = oneString.replace(r'^(.?)*(\\[^n])+(.?)*$', "")
    oneString = re.sub(r'^(.?)*(\\[^n])+(.?)*$', "", oneString)
    print(oneString)
    replacedStrings.insert(i, oneString)

    i += 1

print(replacedStrings)

My aim here is: I need the values only (without the escaped sequences) as the split strings.

My approach here is:

1. I have split the string by \\n that gives me array list of separate strings.
2. Then, I have checked each string using the regex, if the regex matches, then the matched substring is replaced to "".
3. Then I have pushed those strings to a collection, thinking that it will store the replaced strings in the new array list.

So basically, I am through with 1 and 2, but currently I am stuck at 3. Following is my Output:

1
2
3

4

['1\r\r\t\r', '2\r\r', '3\r\r\r\r', '\r', '\r4', '\r']

Answer 1

You might find it easier to use re.findall here with the simple pattern \\S+ :

input = "1\r\r\t\r\n2\r\r\n3\r\r\r\r\n\r\n\r4\n\r"
output = re.findall(r'\S+', input)
print(output)

['1', '2', '3', '4']

This approach will isolate and match any islands of one or more non whitespace characters.

Edit:

Based on your new input data, we can try matching on the pattern [^\\r\\n\\t]+ :

input = "jkahdjkah \r\r\t\r\nA: B\r\r\nA : B\r\r\r\r\n\r\n\r4\n\r"
output = re.findall(r'[^\r\n\t]+', input)
print(output)

['jkahdjkah ', 'A: B', 'A : B', '4']

re.sub isn't really the right tool for the job here. What would be on the table is split or re.findall , because you want to repeatedly match/isolate a certain part of your text. re.sub is useful for taking a string and transforming it to something else. It can be used to extract text, but does not work so well for multiple matches.

Answer 2

You were almost there, I would just use string.strip() to replace multiple \\r and \\n at the start and the end of the strings

String = "1\r\r\t\r\n2\r\r\n3\r\r\r\r\n\r\n\r4\n\r"
splitString = String.split('\n')
replacedStrings = []
i=0

for oneString in splitString:
    s = oneString.strip()
    if s != '':
        print(s)
        replacedStrings.append(s)

print(replacedStrings)

The output will look like

1
2
3
4
['1', '2', '3', '4']

For "jkahdjkah \\r\\r\\t\\r\\nA: B\\r\\r\\nA : B\\r\\r\\r\\r\\n\\r\\n\\r4\\n\\r" , the output will be ['jkahdjkah', 'A: B', 'A : B', '4']

Answer 3

I have found one more method, this seems to work fine, it might not be as optimised as the other answers, but its just another way:

import re
splitString = []
String = "jhgdf\r\r\t\r\nA  : B\r\r\nA  : B\r\r\r\r\n\r\n\rA: B\n\r"
splitString = re.compile('[\r\t\n]+').split(String)
if "" in splitString:
  splitString.remove("")
print(splitString)

I added it here, so that people going through the same trouble as me, might want to overlook this approach too.

Following is the Output that I have got after using the above code:

['jhgdf', 'A  : B', 'A  : B', 'A: B']