How may I count number of rasters in a list of raster stack

Question

I have a list of raster stacks that each raster stack contains unequal number of rasters. How can I sum up number of rasters in my list? I have tried length() but this only returns number of stacks in my list! example data:

library(raster)

#reproducible example
set.seed(987)

#our list of rasters
r.lst <- as.list(1:3)

# setting up list pf raster stacks
r1 <- raster(nrows = 1, ncols = 1, res = 0.5, xmn = -1.5, xmx = 1.5, ymn = -1.5, ymx = 1.5, vals = runif(36, 1, 5))
r.lst[[1]] <- stack(lapply(1:7, function(i) setValues(r1,runif(ncell(r1)))))
r.lst[[2]] <- stack(lapply(1:3, function(i) setValues(r1,runif(ncell(r1)))))
r.lst[[3]] <- stack(lapply(1:2, function(i) setValues(r1,runif(ncell(r1)))))

score 2 · Answer 1 · answered Apr 12 '19 at 07:59

2

One way to do this is as below:

# count sum rasters
n <- Reduce(`+`, lapply(r.lst, nlayers))
n
#[1] 12

answered Apr 12 '19 at 07:59

Majid

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score 1 · Answer 2 · answered Apr 12 '19 at 07:53

1

You can use nlayers to get the number of layers (rasters) in a stack and lapply to apply that function on every element of your list:

lapply(my.list.of.rasterstacks, nlayers)

To sum them all up:

sum(unlist(lapply(my.list.of.rasterstacks, nlayers)))

answered Apr 12 '19 at 07:53

Where's my towel

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score 1 · Answer 3 · answered Apr 12 '19 at 08:11

1

How about:

sum(sapply(r.lst, nlayers))
# [1] 12

or

sum(sapply(r.lst, dim)[3, ])
# [1] 12

answered Apr 12 '19 at 08:11

zx8754

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RoB · Answer 4 · 2019-04-12T08:17:34.827

0

Without minimal data it's hard to answer

EDIT

With the example data, @Where's my towel has the correct answer

sum(unlist(lapply(r.lst, nlayers)))

Consider taking a look at this post on how to make a good reproducible example for future questions.

edited Apr 12 '19 at 08:17

answered Apr 12 '19 at 07:43

RoB

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This give me an error. For example data it is: 3 arguments passed to 'length' which requires 1 – Armenia22 Apr 12 '19 at 08:01
Fixed it. Thank you for including the example. – RoB Apr 12 '19 at 08:19
Thank @RomainB. I thought this really does not need example data as it was a straightforward question. But I have now much better solutions. – Armenia22 Apr 12 '19 at 15:41

How may I count number of rasters in a list of raster stack

4 Answers4