Thanks Mike (& Craig) for confirming that iteration of some sort is the way to go.
It’s interesting that the url container can be addressed directly, instead of loading the file - I’d not seen that before. I’m currently pulling each file into a regular variable, so will probably stick with that as only a few (existing) lines of code would be saved and the net overall effect on timing / resources is probably marginal if the file gets loaded behind the scenes anyway. As the column names/numbers vary by CSV file name - which I have built-out in a ColumnsOfInterest field - it looks like I’ll also be safe to iterate through these items to build the row extraction line dynamically, too. Great, thanks again - I have a direction of travel. Best, Keith.. > On 20 Sep 2016, at 21:32, Mike Bonner <bonnm...@gmail.com> wrote: > > If a file you can do this.. > > repeat for each line tline in url "file:yourfilename.csv" > put item 1 of tLine & comma & item 3 of tline & comma & item 15 of tLine & > return after tExtracted > end repeat > delete the last char of tExtracted -- remove the extraneous return > > Or you can put them into an array or whatever. It should be VERY fast. If > the files are very large, you can instead open the file for read, read a > line, extract the data as above, and repeat till the end of the file. I > think using repeat for each with a file url loads the whole thing at once > then goes line to line, but I'm not sure of that. > > On Tue, Sep 20, 2016 at 2:16 PM, Keith Clarke <keith.cla...@me.com> wrote: > >> Hi folks, >> I’ve a large number of sizeable CSV files from each of which I need to >> extract just 2 or 3 specific columns. Creating nested iterations through >> every item in every line seems somewhat inefficient - as does loading each >> full file into memory - so I feel I must be missing a trick here. >> >> Does Livecode support any elegant way of directly manipulating or >> ‘querying’ (like SQL) delimited data, to extract numbered (or named) >> columns/items - such as 1(Id), 3(Name) & 15(Summary) - from in each line >> from a CSV container or direct from a file/URL? >> Best, >> Keith.. >> _______________________________________________ >> use-livecode mailing list >> use-livecode@lists.runrev.com >> Please visit this url to subscribe, unsubscribe and manage your >> subscription preferences: >> http://lists.runrev.com/mailman/listinfo/use-livecode > _______________________________________________ > use-livecode mailing list > use-livecode@lists.runrev.com > Please visit this url to subscribe, unsubscribe and manage your subscription > preferences: > http://lists.runrev.com/mailman/listinfo/use-livecode _______________________________________________ use-livecode mailing list use-livecode@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-livecode
