Re: [R] retrieve rows from frame assuming criterion

From: Marc Schwartz <MSchwartz_at_medanalytics.com>
Date: Fri 23 Jul 2004 - 23:58:45 EST

On Fri, 2004-07-23 at 08:36, Luis Rideau Cruz wrote:
> Hi all,
>
> I have a data frame in which one column(PUNTAR) is of character type.
> What I want is to retrieve is the frame but only with those rows
> matching elements of PUNTAR with a list characters (e.g
> c("IX49","IX48") )
>
> Year TUR STODNR PUNTAR
> 1994 9412 94020061 IX49
> 1994 9412 94020062 IX48
> 1994 9412 94020063 X32
> 1994 9412 94020065 X23
> 1994 9412 94020066 X27
> 1994 9412 94020067 XI19
> 1994 9412 94020068 XI16
> 1994 9412 94020069 XI14
> 1994 9412 94020070 XI8
> 1994 9412 94020071 X25
> 1994 9412 94020072 X18
> 1994 9412 94020073 II23
> 1994 9412 94020074 XII33
> 1994 9412 94020075 XII31
>
> "my.function"("frame") should be then equal to
>
> Year TURNR STODNR M_PUNTAR
> 1994 9412 94020061 IX49
> 1994 9412 94020062 IX48
>
> Thank you in advance

For a simple subset like this, something like the following, presuming that your data frame is called MyData:

 MyData[MyData$PUNTAR %in% c("IX49", "IX48"), ]   Year TUR STODNR PUNTAR
1 1994 9412 94020061 IX49
2 1994 9412 94020062 IX48

This basically says to select only those rows where the value of MyData$PUNTAR is in c("IX49", "IX48").

If you need to engage in more complex boolean comparisons for subsetting, especially on multiple columns, then the function subset() would be better suited.

HTH, Marc Schwartz



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