如何从 python 中的字符串中提取特定值？

Question

I have a string with this structure:

[519.1743772241992, 519.1743772241992, 519.1743772241992, 519.1743772241992, 519.1743772241992, 519.1743772241992],12,160p30

I need to find the value after ], that here is 12 . I need this value to use in a for loop. how can I do this?

Answer 1

If all you want is at the right end of your string, you can use rsplit instead of split

s = "[519.1743772241992, 519.1743772241992, 519.1743772241992, 519.1743772241992, 519.1743772241992, 519.1743772241992],12,160p30"
val = s.rsplit(",", 2)[1]  # val get value "12" from s

rsplit will split your string from the right starting at the separator "," a maximum of 2 times. As you want the second to last value of your string, use indexing to get the desired value.

Answer 2

If you have same structure of data you can use regexp to extract part of strings you need to use. In described case it can be done like this:

import re


test_string = '[519.1743772241992, 519.1743772241992, 519.1743772241992, '\
                '519.1743772241992, 519.1743772241992, 519.1743772241992],'\
                '12,160p30'

pattern = r'(^\[.+\]),([0-9]+),(.+$)'

result = re.search(pattern, test_string)

print(result.group(1))
# [519.1743772241992, 519.1743772241992, 519.1743772241992, 519.1743772241992, 519.1743772241992, 519.1743772241992]

print(result.group(2))
# 12

print(result.group(3))
# 160p30

Answer 3

string = "[519.1743772241992, 519.1743772241992, 519.1743772241992, 519.1743772241992, 519.1743772241992, 519.1743772241992],1,160p30"
i = string.rfind("],") + 2
value = int(string[i : string.find(",", i)])
print(value)