[slang-users] Re: Using the csv module

[Morten Bo Johansen <mbj@xxxxxxxxxxx>]

Hi John,
                                                          
Pardon the top-posting, but this is very nice and certainly a
lot simpler. I couldn't have figured that out for myself.
                                                          
Thank you for all your work,
Morten

John E. Davis <jed@xxxxxxxxxxx> wrote:

> Hi Morten,
> 
> Morten Bo Johansen <mbj@xxxxxxxxxxx> wrote:
> > Hi
> >
> > I am dabbling a little with the csv module. I would like to
> > create a few functions whereby I can calculate my daily intake
> > of various nutrients from a csv data file and print out how
> > these align to the official recommendations. I suspect the
> > results from my diet will be appalling, but that's another
> > matter ;)
> >
> > Of course, I need to be able get the data from the intersecting
> > cells of rows and columns. The lines (very curtailed) of the
> > data file look like this in an English version:
> >
> >   ,,,Waste,"Energy, kJ","Energy, kcal",Nitrogen-to-protein factor,"Nitrogen, total" ...
> >   Number,Group,Name,%,kJ,kcal,-,g,g,g,g,g ...
> >   1,Soft fruit,"Strawberry, raw",4,162,38,6.25,0.106 ...
> >   2,Pome fruit,"Apple, raw, all varieties",10,233,55,6.25,0.043 ...
> >   3,Tropical or subtropical fruit,"Banana, raw",41,396,93,6.25,0.183 ...
> >   4,Root and tuber vegetables,"Potato, raw",25,326,77,6.25,0.324 ...
> 
> The first two lines appear to be a header that gives names to the
> columns.  I think that it would be better to use a single header line
> containing distinct column names:
> 
>   number,group,name,pct_waste,en_kJ,en_kcal,N2_protein_factor,N2_total,...
>   1,Soft fruit,"Strawberry, raw",4,162,38,6.25,0.106 ...
>   2,Pome fruit,"Apple, raw, all varieties",10,233,55,6.25,0.043 ...
>   3,Tropical or subtropical fruit,"Banana, raw",41,396,93,6.25,0.183 ...
>   4,Root and tuber vegetables,"Potato, raw",25,326,77,6.25,0.324 ...
> 
> The use of this single header is also consistent with RFC 4180
> <https://tools.ietf.org/html/rfc4180>.
> 
> If you then read the file using
> 
>    csv = csv_readcol (csv_file; has_header);
> 
> then csv will be a struct with whose field names correspond to the
> (lower-cased) column names specified in the file, e.g., csv.number
> would be an array with values ["1","2","3","4"].
> 
> In the example you gave below, you want to know the number of kJ for
> a raw strawberry.  To get this, you would use:
> 
>    strawberry_kj = csv.en_kj[wherefirst(csv.name == "Strawberry, raw")];
> 
> Or, if you want to get all the values associated with the strawberry
> you can use:
> 
>    strawberry
>      = struct_filter (csv, wherefirst(csv.name == "Strawberry, raw"); copy);
> 
>    strawberry_kj = strawberry.en_kj;
>    strawberry_kcal = strawberry.en_kcal;
>       .
>       .
> 
> Does this help?  I think that it is far simpler than your approach.
> Thanks,
> --John
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