R help - Feb 2008 - how to generate a column based on other columns in a data frame

HI,

 

I am working on a data set with multiple collections of mosquitoes at
sampling sites. Each row represents a collection of individual samples
with coordinates for each collection. 

... X,  Y,...

1  36.435 30.118

2  36.435 30.118

3  36.435 30.118

4  35.329 29.657

5  35.329 29.657

6  36.431 30.111

7  36.431 30.111

8  35.421 29.797

9  35.421 29.797

10 35.421 29.797

 

Unfortunately, there is no 'site' entry. I would like to add a column of
'site' based on the coordinates of samples so that samples from the same
sites have the same site ID like S1, S2,.... 

 

How to do this in R way? Thanks.

 

 

Weidong Gu, 

Department of Medicine
University of Alabama, Birmingham
1900 University Blvd., Birmingham, Alabama 35294
Email: wgu@uab.edu
PH: (205)-975-9053

 


	[[alternative HTML version deleted]]

Try this:

x2 <- merge(x, cbind(unique(x), Site=sprintf("S%d",
seq_len(nrow(unique(x))))), by=c("X", "Y"))
x2[order(x2$site)]

On 11/02/2008, Weidong Gu <wgu at uab.edu> wrote:
> HI,
>
>
>
> I am working on a data set with multiple collections of mosquitoes at
> sampling sites. Each row represents a collection of individual samples
> with coordinates for each collection.
>
> ... X,  Y,...
>
> 1  36.435 30.118
>
> 2  36.435 30.118
>
> 3  36.435 30.118
>
> 4  35.329 29.657
>
> 5  35.329 29.657
>
> 6  36.431 30.111
>
> 7  36.431 30.111
>
> 8  35.421 29.797
>
> 9  35.421 29.797
>
> 10 35.421 29.797
>
>
>
> Unfortunately, there is no 'site' entry. I would like to add a
column of
> 'site' based on the coordinates of samples so that samples from the
same
> sites have the same site ID like S1, S2,....
>
>
>
> How to do this in R way? Thanks.
>
>
>
>
>
> Weidong Gu,
>
> Department of Medicine
> University of Alabama, Birmingham
> 1900 University Blvd., Birmingham, Alabama 35294
> Email: wgu at uab.edu
> PH: (205)-975-9053
>
>
>
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

-- 
Henrique Dallazuanna
Curitiba-Paran?-Brasil
25? 25' 40" S 49? 16' 22" O

Assuming this data frame:
DF <- data.frame(X = c(36.435, 36.435, 36.435, 35.329, 35.329,
36.431, 36.431, 35.421, 35.421, 35.421), Y = c(30.118, 30.118,
30.118, 29.657, 29.657, 30.111, 30.111, 29.797, 29.797, 29.797))

# Try this:
DF$site <- as.numeric(factor(interaction(DF$X, DF$Y)))

If X and Y can vary slightly while still referring to the same
site then round them first to k decimal places first.  See ?round


On Feb 11, 2008 11:30 AM, Weidong Gu <wgu at uab.edu>
wrote:
> HI,
>
>
>
> I am working on a data set with multiple collections of mosquitoes at
> sampling sites. Each row represents a collection of individual samples
> with coordinates for each collection.
>
> ... X,  Y,...
>
> 1  36.435 30.118
>
> 2  36.435 30.118
>
> 3  36.435 30.118
>
> 4  35.329 29.657
>
> 5  35.329 29.657
>
> 6  36.431 30.111
>
> 7  36.431 30.111
>
> 8  35.421 29.797
>
> 9  35.421 29.797
>
> 10 35.421 29.797
>
>
>
> Unfortunately, there is no 'site' entry. I would like to add a
column of
> 'site' based on the coordinates of samples so that samples from the
same
> sites have the same site ID like S1, S2,....
>
>
>
> How to do this in R way? Thanks.
>
>
>
>
>
> Weidong Gu,
>
> Department of Medicine
> University of Alabama, Birmingham
> 1900 University Blvd., Birmingham, Alabama 35294
> Email: wgu at uab.edu
> PH: (205)-975-9053
>
>
>
>
>        [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>