[R] apply and cor()

[David L Carlson]

Actually, not using apply() would be faster and simpler

cor(t(compare_data), t(test_data))

David C

-----Original Message-----
From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of David L Carlson
Sent: Friday, May 12, 2017 10:48 AM
To: Ismail SEZEN <sezenismail at gmail.com>; Micha Silver <tsvibar at gmail.com>
Cc: R-help at r-project.org
Subject: Re: [R] apply and cor()

Actually, r is a vector, not an index value. You need

apply(compare_data, 1, function(r) cor(r, t(test_data)))

-------------------------------------
David L Carlson
Department of Anthropology
Texas A&M University
College Station, TX 77840-4352



-----Original Message-----
From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Ismail SEZEN
Sent: Friday, May 12, 2017 10:11 AM
To: Micha Silver <tsvibar at gmail.com>
Cc: R-help at r-project.org
Subject: Re: [R] apply and cor()


> On 12 May 2017, at 17:57, Micha Silver <tsvibar at gmail.com> wrote:
> 
> I have two data.frames, one with a single row of 31 columns, and the second with 269 rows and the same 31 columns.
> > dim(compare_data)
> [1] 269  31
> > dim(test_data)
> [1]  1 31
> 
> I want to apply cor() between the one row of 'test_data', and each row of the 'compare_data' .
> I tried 'apply' but I get this error:
> > apply(compare_data, 1, function(r) {cor(compare_data[r,], test_data)})
> Error in cor(compare_data[r, ], test_data) : incompatible dimensions


apply(compare_data, 1, function(r) {cor(compare_data[r,], as.numeric(test_data))})

See ?cor. Explanation of y is "NULL (default) or a vector, matrix or data frame with compatible dimensions to x”.

> 
> 
> In order to try to understand I did:
> > dims <- apply(compare_data, 1, function(r) {dim(compare_data[r,])})
> > head(dims)
>     20 73 103 118 130 142 151 154 191 205 217 222 227 232 240 275 282 301 320 359 360 551 589 653 789 801 808 812
> [1,]  9  8   8   9   5   9   8  11   6  15  12  13  10   7   9  14 8  11   9  11  11  12   9  14   5   8   9  10
> [2,] 31 31  31  31  31  31  31  31  31  31  31  31  31  31  31  31 31  31  31  31  31  31  31  31  31  31  31  31
>     840 856 857 867 885 970 983 985 1103 1107 1197 1207 1237 1262 1279 1282 1332 1357 1358 1392 1411 1435 1458 1473
> [1,]  14  11  12   8  10   2   7   9   10    8   10   13   11 7    9   12   11   11   16   10   10   12   10   10
> [2,]  31  31  31  31  31  31  31  31   31   31   31   31   31   31 31   31   31   31   31   31   31   31   31   31
> 
> and indeed I am getting different row dimensions. I expected "1 31" for each. What are the values 9,8,8,9,5... in the [1,] dimension?
> 
> If I test the compare_data data.frame one row at a time:
> > dim(compare_data['20',])
> [1]  1 31
> > dim(compare_data['1473',])
> [1]  1 31
> 
> It looks as I expected.
> What am I missing??
> 
> Thanks
> 
> -- 
> Micha Silver
> cell: +972-523-665918
> 
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
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> and provide commented, minimal, self-contained, reproducible code.


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______________________________________________
R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.