Python replace() method doesn't keep changes

Question

I have a string that I need to reconstruct with new values. The string looks like this:

log = "2019-06-25T11:09:59+00:00 15.24.137.43 printer: powered up"

I have a list that already contains the values:

list1 = ["2019-06-25T11:09:59+00:00",  "15.24.137.43", "printer", "powered up"]

I have another list that contains the values that I am going to replace in the original log:

list2 = ["date", "ip_address", "device", "event"]

I have tried the following in python:

list2_iteration = 0
for field in list1:
    if(log.find(field) != -1):
        #print(field)
        log.replace(field,list2[list2_iteration])
    list2_iteration += 1
print(log)

What I want to obtain is the reconstructed log such as:

'date ip_address device event'

It seems like the replace() method doesn't keep changes. When I print the log, on the last line, it prints the original log which is:

2019-06-25T11:09:59+00:00 15.24.137.43 printer: powered up

Do you have any idea on how can I keep the changes on the log, so I can have it fully reconstructed at the end? I would appreciate it if anyone would help! Thanks!

.replace() is not an inplace method

ShlomiF
– ShlomiF

2021-06-24 21:09:53 +00:00
Commented Jun 24, 2021 at 21:09 — ShlomiF
– ShlomiF, Commented Jun 24, 2021 at 21:09

Relandom · Accepted Answer · 2021-06-24 21:09:02Z

4

String in python are immutable and replace return new string - it doesn't update old value. Try this:

list2_iteration = 0
for field in list1:
    if(log.find(field) != -1):
        #print(field)
        log = log.replace(field,list2[list2_iteration])
    list2_iteration += 1
print(log)

answered Jun 24, 2021 at 21:09

Relandom

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