R help - Feb 2018 - Identify does sort the locations

Hi,

Using identify function, I think I should get the index of the selected 
points in the order I clicked them. This is what I read in the help. But 
I feel they are ordered. Please let me know what I missed.

In the following example, I clicked on the points labelled 7, 5 and 1, 
but I get 1, 5, 7 as output.
> set.seed(0); x = rnorm(10); y = rnorm(10); plot(x,y); text(x, y, 
> seq(x)); sel = identify(x,y); sel
[1] 1 5 7

Any help appreciated,
Samuel

R version 3.4.3 (2017-11-30)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 7 x64 (build 7601) Service Pack 1

Matrix products: default

locale:
[1] LC_COLLATE=English_United Kingdom.1252  LC_CTYPE=English_United 
Kingdom.1252
[3] LC_MONETARY=English_United Kingdom.1252 LC_NUMERIC=C
[5] LC_TIME=English_United Kingdom.1252

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

loaded via a namespace (and not attached):
[1] compiler_3.4.3

Hi

Indeed the help page says ...

"the indices of the identified points, in the order they were
identified"

... and that is a complete lie.

Sorry about that :(

The simplest thing would be to correct the help page.

It would be possible to have identify() return the order, though for 
backward compatibility that should not be the default, so would require 
another argument to identify().

Paul

On 16/02/18 06:58, Samuel GRANJEAUD IR/INSERM wrote:
> Hi,
> 
> Using identify function, I think I should get the index of the selected 
> points in the order I clicked them. This is what I read in the help. But 
> I feel they are ordered. Please let me know what I missed.
> 
> In the following example, I clicked on the points labelled 7, 5 and 1, 
> but I get 1, 5, 7 as output.
> 
>> set.seed(0); x = rnorm(10); y = rnorm(10); plot(x,y); text(x, y, 
>> seq(x)); sel = identify(x,y); sel
> [1] 1 5 7
> 
> Any help appreciated,
> Samuel
> 
> R version 3.4.3 (2017-11-30)
> Platform: x86_64-w64-mingw32/x64 (64-bit)
> Running under: Windows 7 x64 (build 7601) Service Pack 1
> 
> Matrix products: default
> 
> locale:
> [1] LC_COLLATE=English_United Kingdom.1252? LC_CTYPE=English_United 
> Kingdom.1252
> [3] LC_MONETARY=English_United Kingdom.1252 LC_NUMERIC=C
> [5] LC_TIME=English_United Kingdom.1252
> 
> attached base packages:
> [1] stats???? graphics? grDevices utils???? datasets? methods?? base
> 
> loaded via a namespace (and not attached):
> [1] compiler_3.4.3
> 
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
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> PLEASE do read the posting guide 
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-- 
Dr Paul Murrell
Department of Statistics
The University of Auckland
Private Bag 92019
Auckland
New Zealand
64 9 3737599 x85392
paul at stat.auckland.ac.nz
http://www.stat.auckland.ac.nz/~paul/

Hi Paul,

Thanks for your answer. I am wondering if in the previous versions, 
let's say 2.1x, the data were in the selection order... Let me know if 
there a R fonction taht I can code. Do you think I should use locator 
function and match points on my own?

Best,
Samuel

Hi Samuel GRANJEAUD,



Isn't this loop more simple to retain the click-order:


result = numeric(n)
for (i in 1:n) {
	id = identify(x, y, n=1)
	result[i] = id
	}

Hope this helps,

Best regards,


Franklin Bretschneider
Dept of Biology
Utrecht University
bretschr at xs4all.nl