如何从我的字符串中检索子字符串？

Question

The string variable myvar can have the following values:

261.30 (NM) / 300.76 (MI) / 483.93 (KM)
952.27 (NM) / 1,096.09 (MI) / 1,763.61 (KM)

I need to extract the numbers 483.93 and 1,763.61 . These numbers should be converted to float numbers or rounded up to integers.

This is what I tried:

mylar = "261.30 (NM) / 300.76 (MI) / 483.93 (KM)"
int(myvar[28:-8])

It works in the first case ( 261.30 (NM) / 300.76 (MI) / 483.93 (KM) ). But it fails in case of 952.27 (NM) / 1,096.09 (MI) / 1,763.61 (KM) . Is there any generic solution?

Answer 1

You can use this regex that detects the last number in the string and places it in group1,

([^ ]*)[^\d]*$

Demo

Then with following python code, you can convert it into float or int. I am converting it to float as they are decimal values but you can easily cast them to int.

import re

arr = ['261.30 (NM) / 300.76 (MI) / 483.93 (KM)','952.27 (NM) / 1,096.09 (MI) / 1,763.61 (KM)']

for s in arr:
 val = re.search(r'([^ ]*)[^\d]*$', s)
 floatval = float(re.sub(r',','',val.group(1)))
 print('Float value: ' + str(floatval))
 print('Int value: ' + str(int(floatval)))

Prints,

Float value: 483.93
Int value: 483
Float value: 1763.61
Int value: 1763

Answer 2

With single re.search function, without any replacement:

import re

myvar = '952.27 (NM) / 1,096.09 (MI) / 1,763.61 (KM)'
num = re.search(r'\/\s+(\d+),?(\d+\.\d+)\s+\(KM\)', myvar)
if num:
    num = float(num.group(1) + num.group(2))

print(num)

The output:

1763.61

Answer 3

You could also achieve the same by using only split()

str1="261.30 (NM) / 300.76 (MI) / 483.93 (KM)"
last_num_string=str1.split('/')[2].split('(')[0]
last_num_float=float(last_num_string)
print(last_num_float)

Answer 4

What I would do in this case is create a list of the values, from which I can extract any of those.

myvar2 = myvar.replace("/", "").replace(",", "")
myvar2 = myvar2.split()
# This gives a list like this: ["261.30","(NM)","300.76","(MI)","483.93","(KM)"]
myfloat = float(myvar[4]) # This will return 483.93 on the first string and 1,763.61 on the second.

Answer 5

You can do it with regular expression.

import re

target = '952.27 (NM) / 1,096.09 (MI) / 1,763.61 (KM)'

regex = r'.* \(NM\) \/ .* \(MI\) \/ (.*) \(KM\)'

res_str = re.findall(regex, target)
float_str = res_str[0].replace(',', '') 
result = float(float_str)

Answer 6

import re
m="261.30 (NM) / 300.76 (MI) / 483.93 (KM)"
print(float(re.split('\/',re.sub(',','',m))[2][:-5]))

Answer 7

Since the values are followed by (KM) you could use a positive lookahead:

\S+(?= \(KM\))

• \\S+ Match 1+ non whitespace characters
• (?= \\(KM\\)) Positive lookahead to check what is on the right is a space and (KM)

For example:

regex = r"\S+(?= \(KM\))"
strings = ["261.30 (NM) / 300.76 (MI) / 483.93 (KM)", "952.27 (NM) / 1,096.09 (MI) / 1,763.61 (KM)"]

for s in strings:
    matches = re.search(regex, s)
    if matches:
        print(float(matches.group().replace(',', '')))

That will give you:

483.93
1763.61

Regex demo | Python demo