使用“ re.findall”分割字符串时出错

Question

i need to split a string into three values (x,y,z) the string is something like this (48,25,19)

i used "re.findall" and it works fine but sometimes it produces this error

(plane_X, plane_Y, plane_Z = re.findall("\\d+.\\d+", planepos)

ValueError: not enough values to unpack (expected 3, got 0))

this is the code:

    def read_data():
        # reading from file
        file = open("D:/Cs/Grad/Tests/airplane test/Reading/Positions/PlanePos.txt", "r")
        planepos = file.readline()
        file.close()
        file = open("D:/Cs/Grad/Tests/airplane test/Reading/Positions/AirportPosition.txt", "r")
        airportpos = file.readline()
        file.close()
        # ==================================================================
        # spliting and getting numbers
        plane_X, plane_Y, plane_Z = re.findall("\d+\.\d+", planepos)
        airport_X, airport_Y, airport_Z = re.findall("\d+\.\d+", airportpos)
        return plane_X,plane_Y,plane_Z,airport_X,airport_Y,airport_Z

what i need is to split the string (48,25,19) to x=48,y=25,z=19 so if someone know a better way to do this or how to solve this error will be appreciated.

Answer 1

You can use ast.literal_eval which safely evaluates your string:

import ast

s = '(48,25,19)'
x, y, z = ast.literal_eval(s)

# x => 48
# y => 25
# z => 19

Answer 2

Your regex only works for numbers with a decimal point and not for integers, hence the error. You can instead strip the string of parentheses and white spaces, then split the string by commas, and map the resulting sequence of strings to the float constructor:

x, y, z = map(float, planepos.strip('() \n').split(','))

Answer 3

If your numbers are integers, you can use the regex:

re.findall(r"\d+","(48,25,19)")                                         
['48', '25', '19']

If there are mixed numbers:

re.findall(r"\d+(?:\.\d+)?","(48.2,25,19.1)")                           
['48.2', '25', '19.1']