use of 'cbind' on numerous coordinates using a loop

Question

I have a lot of coordinates:

> xh1
[1] 257283.7 258592.6 261811.6 262768.6 257283.7
> yh1
[1] 2639722 2640722 2640722 2639722 2639722
> xh2
[1] 257283.7 256523.3 263725.6 262768.6 257283.7
> yh2
[1] 2639722 2638722 2638722 2639722 2639722
... ...

Using 'cbind', I want to prepare the coordinates to be converted into polygons as:

poly1<-cbind(xh1,yh1)
poly2<-cbind(xh2,yh2)
... ...

> poly1
          xh1     yh1
[1,] 257283.7 2639722
[2,] 258592.6 2640722
[3,] 261811.6 2640722
[4,] 262768.6 2639722
[5,] 257283.7 2639722
... ...

poly<- Polygon(poly1)
... ...

Is it possible to use a loop to do the 'cbind' task in R?? I know anything like below is not going to work:

poly<-lapply(1:100, function(i) cbind(paste0("xh",i), paste0("yh",i)))

Answer 1

Use get to fetch the value of a variable given its name. So in your code above, replace paste0("xh",i) with get(paste0("xh",i)), and likewise for yh. In other words, try

poly<-lapply(1:100, function(i) cbind(get(paste0("xh",i)), get(paste0("yh",i))))

(I can't help wondering why you're using separate variables xh1, xh2, ... instead of a matrix or data frame xh with columns 1, 2, ...)