[R] Matrix of indexes to extract sparse data in dataframe

[John Kane]

d1  <-  apply(c0, 1, min)  I think does it.

John Kane
Kingston ON Canada


> -----Original Message-----
> From: sergio.fonda99 at gmail.com
> Sent: Fri, 5 Jun 2015 15:06:34 +0200
> To: r-help at r-project.org
> Subject: [R] Matrix of indexes to extract sparse data in dataframe
> 
> I would like to avoid a "for loop" to get a vector of data taken from
> rows of a data frame for specific columns.
> An example is the following (I can't apply min to every row of df, this
> is
> just an example):
> 
> c0=data.frame(a=c(3,-2,12,7,-23,17) , b=c(-1,-3,14,2,6,19))
> c1=apply(c0,1,which.min)
>> c1
> [1] 2 2 1 2 1 1
> 
> I would like to get a result like the following call, but without
> employing a "for loop":
> 
> d1=c(c0[1,c1[1]], c0[2,c1[2]], c0[3,c1[3]], c0[4,c1[4]], c0[5,c1[5]],
> c0[6,c1[6]])
>> d1
> [1]  -1  -3  12   2 -23  17
> 
> Thanks a lot for any help!
> 
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