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How best to convert a string "list" to a python list

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  How best to convert a string "list" to a python list noydb <jenn.duerr@gmail.com> - 2011-05-13 10:15 -0700
    Re: How best to convert a string "list" to a python list Jerry Hill <malaclypse2@gmail.com> - 2011-05-13 13:30 -0400
    Re: How best to convert a string "list" to a python list MRAB <python@mrabarnett.plus.com> - 2011-05-13 18:36 +0100
    Re: How best to convert a string "list" to a python list Redcat <redcat@catfolks.net> - 2011-05-13 19:26 +0000
    Re: How best to convert a string "list" to a python list Nobody <nobody@nowhere.com> - 2011-05-14 09:41 +0100
      Re: How best to convert a string "list" to a python list Daniel Kluev <dan.kluev@gmail.com> - 2011-05-14 21:16 +1100
      Re: How best to convert a string "list" to a python list Terry Reedy <tjreedy@udel.edu> - 2011-05-14 15:59 -0400

#5310 — How best to convert a string "list" to a python list

I want some code to take the items in a semi-colon-delimted string
"list" and places each in a python list.  I came up with below.  In
the name of learning how to do things properly, do you experts have a
better way of doing it?

Thanks for any inputs!

***
x = "red;blue;green;yellow" ## string of semi-colon delimited colors

color_list = []
## sc = semi-colon

while x.find(";") <> -1:
    sc_pos = x.find(";")
    current_color = x[0:sc_pos] ## color w/o sc
    current_color_sc = x[0:sc_pos+1] ## color with sc
    color_list.append(current_color) ## append color to list
    x = x.replace(current_color_sc, "") ## remove color and sc from
string
    print current_color
    print color_list
    print x + "\n"

color_list.append(x) # append last color left in x (no sc at end of
string)
print color_list

print "done"

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#5312

On Fri, May 13, 2011 at 1:15 PM, noydb <jenn.duerr@gmail.com> wrote:
> I want some code to take the items in a semi-colon-delimted string
> "list" and places each in a python list.  I came up with below.  In
> the name of learning how to do things properly, do you experts have a
> better way of doing it?

Strings have a split method, which splits the string into a list based
on a delimiter, like this:

>>> x = "red;blue;green;yellow"
>>> color_list = x.split(";")
>>> print color_list
['red', 'blue', 'green', 'yellow']

That's how I'd do it.

-- 
Jerry

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#5315

On 13/05/2011 18:15, noydb wrote:
> I want some code to take the items in a semi-colon-delimted string
> "list" and places each in a python list.  I came up with below.  In
> the name of learning how to do things properly, do you experts have a
> better way of doing it?
>
> Thanks for any inputs!
>
> ***
> x = "red;blue;green;yellow" ## string of semi-colon delimited colors
>
> color_list = []
> ## sc = semi-colon
>
> while x.find(";")<>  -1:
>      sc_pos = x.find(";")
>      current_color = x[0:sc_pos] ## color w/o sc
>      current_color_sc = x[0:sc_pos+1] ## color with sc
>      color_list.append(current_color) ## append color to list
>      x = x.replace(current_color_sc, "") ## remove color and sc from
> string
>      print current_color
>      print color_list
>      print x + "\n"
>
> color_list.append(x) # append last color left in x (no sc at end of
> string)
> print color_list
>
> print "done"

 >>> x = "red;blue;green;yellow"
 >>> x.split(";")
['red', 'blue', 'green', 'yellow']

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#5318

On Fri, 13 May 2011 10:15:29 -0700, noydb wrote:

> I want some code to take the items in a semi-colon-delimted string
> "list" and places each in a python list.  I came up with below.  In the
> name of learning how to do things properly, do you experts have a better
> way of doing it?

How about the below?

dan@dan:~/development$ python
Python 2.6.6 (r266:84292, Dec 27 2010, 00:02:40) 
[GCC 4.4.5] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> x = "cyan;magenta;yellow;black"
>>> xList = x.split(';')
>>> xList
['cyan', 'magenta', 'yellow', 'black']
>>>

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#5351

On Fri, 13 May 2011 10:15:29 -0700, noydb wrote:

> I want some code to take the items in a semi-colon-delimted string "list"
> and places each in a python list.  I came up with below.  In the name of
> learning how to do things properly, do you experts have a better way of
> doing it?

> x = "red;blue;green;yellow" ## string of semi-colon delimited colors

Provided that a semicolon is *always* a delimiter, just use the .split()
method:

	color_list = x.split(";")

For more complex formats, where there are quote and/or escape characters
which allow the delimiter to occur as part of an item, you typically need
to use a regular expression to match everything up to the next delimiter,
and do this in a loop to extract the individual items.

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#5360

On Sat, May 14, 2011 at 7:41 PM, Nobody <nobody@nowhere.com> wrote:
> to use a regular expression to match everything up to the next delimiter,
> and do this in a loop to extract the individual items.

re.findall() should let you match all items at once, without loop.

-- 
With best regards,
Daniel Kluev

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#5383

On 5/14/2011 4:41 AM, Nobody wrote:
> On Fri, 13 May 2011 10:15:29 -0700, noydb wrote:
>
>> I want some code to take the items in a semi-colon-delimted string "list"
>> and places each in a python list.  I came up with below.  In the name of
>> learning how to do things properly, do you experts have a better way of
>> doing it?
>
>> x = "red;blue;green;yellow" ## string of semi-colon delimited colors
>
> Provided that a semicolon is *always* a delimiter, just use the .split()
> method:
>
> 	color_list = x.split(";")
>
> For more complex formats, where there are quote and/or escape characters
> which allow the delimiter to occur as part of an item, you typically need
> to use a regular expression to match everything up to the next delimiter,
> and do this in a loop to extract the individual items.

Or, for some formats, use the cvs module.


-- 
Terry Jan Reedy

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