On Tue, Mar 25, 2014 at 4:50 AM, Vincent Davis <vinc...@vincentdavis.net> wrote: > I have several csv file I need to append (vertically). They have different > but overlapping headers. For example; > file1 headers ['a', 'b', 'c'] > file2 headers ['d', 'e'] > file3 headers ['c', 'd'] > > Is there a better way than this
Summary of your code: 1) Build up a set of all headers used, by opening each file and reading the headers. 2) Go through each file a second time and write them out. That seems like the best approach, broadly. You might be able to improve it a bit (it might be tidier to open each file once, but since you're using two different CSV readers, it'd probably not be), but by and large, I'd say you have the right technique. Your processing time here is going to be dominated by the actual work of copying. The only thing you might want to consider is order. The headers all have a set order to them, and it'd make sense to have the output come out as ['a', 'b', 'c', 'd', 'e'] - the first three from the first file, then adding in everything from subsequent files in the order they were found. Could be done easily enough by using 'in' and .append() on a list, rather than using a set. But if that doesn't matter to you, or if something simple like "sort the headers alphabetically" will do, then I think you basically have what you want. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
