Python string get leading characters up to first comma

Question

I have the following string:

strIn = "Head,0.000235532,0.43656735"

I would like to retrieve from this a variable type = "Head" and an array vals = [0.000235532,0.43656735]

How can I do this using Python? I've considered using strIn[0],...,strIn[5] to get the type, but then I realized I'll get types of various lengths. Thanks.

`str.split` would be a good starting point. – Kevin Dec 04 '14 at 16:47 — Kevin, Dec 04 '14 at 16:47

score 4 · Accepted Answer · edited May 23 '17 at 12:13

4

If you're using Python 3, you can do

type_, *vals = strIn.split(',')
vals = [float(v) for v in vals]  # Convert list of strings to list of floats.

This uses str.split to split the string into a list based on the provided character, and then uses Python 3's extended tuple unpacking to put the first value into type_ and the remaining values into vals. See this answer for more discussion on how to use tuple unpacking.

If you're on Python 2 you can't use the extended unpacking syntax, so you have to add an additional step:

str_list = strIn.split(',')
type_ = str_list[0]
vals = [float(v) for v in str_list[1:]]

edited May 23 '17 at 12:13

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answered Dec 04 '14 at 16:48

Roger Fan

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Note that ``*vals`` will be a list of strings. – Fabio Menegazzo Dec 04 '14 at 16:51
@Menegazzo True. I added a line to convert it to a list of floats. – Roger Fan Dec 04 '14 at 16:52
@jds I think it will work on Python 2.7 as well. Just give it a try. – Fabio Menegazzo Dec 04 '14 at 16:53
@jds Added a version for Python 2. – Roger Fan Dec 04 '14 at 16:56

Mazdak · Answer 2 · 2014-12-04T17:20:30.707

0

As you are in python2 first split with , then use slicing and float function :

>>> none=strIn.split(',')[0]
>>> none
'Head'
>>> vals=map(float,strIn.split(',')[1:])
>>> vals
[0.000235532, 0.43656735]

As type is a built-in name recommended that dont use it !

edited Dec 04 '14 at 17:20

answered Dec 04 '14 at 16:54

Mazdak

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`type` is a special keyword, that code could have surprising consequences ;-) – Stanislav Shabalin Dec 04 '14 at 17:05

Python string get leading characters up to first comma

2 Answers2