[Tutor] 'source' in python or preloading variables

[Alan Gauld]

"John" <washakie at gmail.com> wrote 

>I have a file sitelocations:
> 
> STN_id[1]=AAA
> STNlat[1]=58.800000
> STNlon[1]=17.400000
> STNelv[1]=20
> STN_id[2]=BBB
> STNlat[2]=42.450000
> STNlon[2]=25.583333
> STNelv[2]=2925
> 
> which in shell scripts I can simple 'source'. 

> In Python I have to:

> sitesFile=file('sitelocations','r')
> sites=sitesFile.readlines()
> i=0;
> for l in sites:
>        if i==0:
>                STN_id.append(l.split('=')[1].strip('\n')); i+=1;
>        elif i==1:
>                STNlat.append(l.split('=')[1].strip('\n')); i+=1;
>        elif i==2:
>                STNlon.append(l.split('=')[1].strip('\n')); i+=1;
>        else:
>                STNelv.append(l.split('=')[1].strip('\n')); i=0;
> 
> Is there a better way??

Yes, use the file as an iterator:

sitesFile = open('sitelocations','r')
for line in sitesFile:
          STN_id.append(line.split('=')[1])
          line = sitesFile.next().strip()
          STNlat.append(line.split('=')[1])
          line = sitesFile.next().strip()
          STNlon.append(line.split('=')[1])
          line = sitesFile.next().strip()
          STNelv.append(line.split('=')[1])

No need for messy regex or unsafe exec.
The dictionary solution is potentially safer 
still however since it eliminates the line 
order dependancy.

HTH,

-- 
Alan Gauld
Author of the Learn to Program web site
http://www.freenetpages.co.uk/hp/alan.gauld