CODEWITHSUNDEEP
pythonregexstringpython-3.xcomplex-numbers
Amarth Gûl
Amarth Gûl

Reputation: 1090

Match number in python using re

I got many data wrote in this form(read from file):

(31265+0j)
(-5613.54281374+404.957401125j)
(1371.65134844+2671.06617046j)
...

And yet I want to extract the numerical part, like [31265, 0] or [-5613.54281374 , 404.957401125] , I coded in python in the way I thought it would work:

re.findall(r'.*([\+|\-]?\d+.?\d+)([\+|\-]?\d+.?\d+).*', tempStr)

But it does not work, it gave me this:

[]
[('26', '5+0')]
[('11', '25')]
...

What's wrong with it? Is it something about lazy mode? And how should I fix it?

========================Update======================== For me, this question is solved, but I still wonder what's wrong with the regular expression part, is there someone willing to help me point out what's wrong with the regex pattern?

Upvotes: 2

Views: 177

Answers (2)

e4c5
e4c5

Reputation: 53774

These are numbers. You should not use regex here. The first part is the real and the second part is the imaginary you can access them like this

 n = (-5613.54281374+404.957401125j)
 n.real
 n.imag

This maybe hard to spot at first because in maths we often use i = sqrt(-1) but in python it's j = sqrt(-1) But quit interestingly, if you do

import math
math.sqrt(-1)

you will get a ValueError

Update:

If the data is in a file

with open('complex.txt') as f:
    for line in f:
        number = complex(line.strip())

Update 2: if you really, really, really want to use regex:

 map(float, line[1:-2].split('+'))

Use re.split() instead if you have numbers where the complex part can be negative.

Upvotes: 6

alexjones
alexjones

Reputation: 86

Using .real and .imag will give you the output you desire

   foo = (31265 + 0j)
   bar = [foo.real , bar.imag]
   #>>>[31265.0 , 0.0]

Upvotes: 1

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