[Tutor] better looping construct for replacing elements in file?
Joel Goldstick
joel.goldstick at gmail.com
Thu Feb 2 22:16:54 CET 2012
On Thu, Feb 2, 2012 at 3:50 PM, Brett Longworth <blongworth at whoi.edu> wrote:
> Hello,
>
> Today I wrote a quick script to replace elements in multiple lines of a file
> with corresponding elements from a single line in another file, linking the
> two via an index element. The code iterates through the entire source file
> to find the matching index for each line of the destination file. This
> works, but it's clearly a terrible way to solve the problem. Can someone
> point me to a more efficient, pythonic solution?
>
> thanks,
> -Brett
>
> Code:
>
> wheel = "A794"
> wheelfile = "A794.txt"
> statusfile = "CURRENT.ams"
>
> sfile = csv.reader(open(statusfile), delimiter='\t')
> statusWriter = csv.writer(open('statustest.txt', 'wb'), delimiter='\t',
> quotechar='|', quoting=csv.QUOTE_MINIMAL)
>
> for sline in sfile:
> #print sline
> wfile = csv.reader(open(wheelfile))
> for line in wfile:
> #print line[0]
> #print sline[18]
> if line[0] == sline[18]:
> sline[0] = line [1]
> sline[1] = "OSG"+str(line[4])
> sline[17] = wheel
> sline[21] = line[9]
> statusWriter.writerow(sline)
>
> Excerpt of wheelfile:
>
> "2","X496","02/01/12","OSG","106788","85411","GS-13365","Outside Primary
> Standard | > Modern (1950)","2.43","149177"
> "3","C655","02/01/12","OSG","106534","83028","HY-19231","Outside Blank | >
> 30,000","3.63","149178"
>
> Excerpt of statusfile:
>
> Y002 BET2918 10/18/06 15:32:52 160.00 174 1.000 16408
> 1.306E-12 1.213E-10 402.6 405.9 -42.7 3.2 1.2242
> -0.0220 1.822 -12.66 A499 2 1 5631 86523 data
> 3.7E-6
> Y002 BET2918 10/18/06 15:35:46 150.00 162 1.000 15654
> 1.313E-12 1.226E-10 407.6 410.3 -43.9 2.0 1.2180
> -0.0243 1.894 -13.03 A499 2 1 5631 86523 3.7E-6
> 0003 BET7147 10/18/06 15:55:33 170.00 186 1.000 3442
> 2.903E-13 2.693E-11 357.7 359.3 -46.1 2.5 1.2000
> 0.0276 1.734 -12.86 A499 3 1 5631 86524 3.3E-6
> 0003 BET7147 10/18/06 15:58:49 170.00 185 1.000 3232
> 2.772E-13 2.598E-11 351.8 353.4 -46.1 3.5 1.2000
> 0.0149 1.761 -12.66 A499 3 1 5631 86524 3.2E-6
> 0003 BET7147 10/18/06 16:02:06 170.00 185 1.000 3399
> 2.955E-13 2.753E-11 346.9
>
>
> --
> Brett Longworth
> Research Associate
> Woods Hole Oceanographic Institution
> ph: 508.289.3559
> fax: 508.457.2183
>
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If you are a little savvy with sql you could write each csv to tables,
Since you have csv file input why not write each to a db table. Then
you could join on line[0] == sline[18] and update your 4 fields.
Then dump table as csv
--
Joel Goldstick
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