when 'select' argument is provided, columns should be returned in the order provided to that argument  #1445

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1. arunsrinivasan

   added

   bug

   fread

   on Nov 26, 2015
2. arunsrinivasan

   added this to the v1.9.8 milestone on Nov 26, 2015
3. MichaelChirico commented on Dec 1, 2015

   

   MichaelChirico

   on Dec 1, 2015

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   Any reason to care about the column order? I've noticed this but never particularly minded. Usually the order I specify them in is meaningless.
4. arunsrinivasan commented on Dec 1, 2015

   

   arunsrinivasan

   on Dec 1, 2015

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   @MichaelChirico perhaps because the reason I ran into this issue is due to recently implemented col.names argument. You can't use col.names argument together with select if you can't be sure of the order of columns in the result.

   fread(my_file, select=c("b", "c"), col.names = c("B", "C"))

   names the columns wrongly in this case.. and so one has to do:

   cols = c("b", "c")
   dt = fread(my_file, select=cols)
   setcolorder(dt, cols)
   setnames(dt, cols, c("B", "C"))
5. MichaelChirico commented on Dec 1, 2015

   

   MichaelChirico

   on Dec 1, 2015

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   @arunsrinivasan duly noted, I had missed the col.names update. Very useful.
6. mattdowle commented on Jan 8, 2016

   

   mattdowle

   on Jan 8, 2016

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   Agreed. And fread should error if the column requested isn't present.

   > fread("a,c,b\n1,2,3", select=c("b", "foo"))
      b
   1: 3 
   # To add:  Error: column name "foo" passed to 'select=' not found in data
7. arunsrinivasan

   self-assigned this

   on Mar 5, 2016
8. arunsrinivasan

   closed this as completedin 57dbdceon Mar 6, 2016
9. arunsrinivasan

   added 2 commits that reference this issue on Mar 9, 2016

   Error on invalid cols in 'select' moved to fread.c, #1445.

   99efe89

   Fix stack imbalance in fread, #1445.

   983aede
10. mattdowle

    added a commit that references this issue on Sep 24, 2016

    fread missing select column downgraded from error to warning to pass …

    ...

    7795620
11. HughParsonage

    added a commit that references this issue on Jan 16, 2018

    Reclose #1445: non-monotonic select

    d70e65e