Sum up rasters in R

Question

I have 365 rasters (daily_sm2rain data of a year) in .TIF. I would like to create a new raster which is sum of 365 input rasters in R (~ sum of rain in a year). How can I do this?

I tried input=list.files("path_to_data",pattern="*.tif$"). it's ok.

map <- brick(paste0("path_to_data",input[1])) fives:

Error is "Error in .local(.Object, ...) : Error in .rasterObjectFromFile(x, objecttype = "RasterBrick", ...) : Cannot create a RasterLayer object from this file. (file does not exist)

print(input)
    [1] "daily.rainfall_2018-01-02_10km.tif" "daily.rainfall_2018-01-03_10km.tif"
      [3] "daily.rainfall_2018-01-04_10km.tif" "daily.rainfall_2018-01-05_10km.tif"
      [5] "daily.rainfall_2018-01-06_10km.tif" "daily.rainfall_2018-01-07_10km.tif"
      [7] "daily.rainfall_2018-01-08_10km.tif" "daily.rainfall_2018-01-09_10km.tif"
      [9] "daily.rainfall_2018-01-10_10km.tif" "daily.rainfall_2018-01-11_10km.tif"
     [11] "daily.rainfall_2018-01-12_10km.tif" "daily.rainfall_2018-01-13_10km.tif"
     [13] "daily.rainfall_2018-01-14_10km.tif" "daily.rainfall_2018-01-15_10km.tif
....
361 rows.

Do you know how to read in one raster file? Please show some code so we know where to start. — Spacedman, Aug 17 '19 at 12:56
What do you obtain by just running paste0("path_to_data",input[1])? — Chelmy88, Aug 19 '19 at 11:07

score 9 · Answer 1 · answered Aug 19 '19 at 13:17

9

So close, use:

files = list.files("path_to_data",pattern="*.tif$", full.names=TRUE)

rs <- brick(files)

or

rs <- stack(files)

Don't use map as name, there're several R functions with the same name.

Then, to create a sum of all your rasters use calc function (from raster package):

rs1 <- calc(rs, sum)

answered Aug 19 '19 at 13:17

aldo_tapia

13,560
5
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Thanks aldo_tapia so much. It worked. – quoc-non duong Aug 19 '19 at 14:49
You're welcome. You can accept the answer if you want, closing this topic – aldo_tapia Aug 19 '19 at 15:03

score 2 · Answer 2 · answered Aug 17 '19 at 10:07

2

You can read the raster in R with the rasterpackage.

It can be loaded with map <- brick("file_path"). Then you can apply addition operation between your loaded objects. If you have 365 of them, you should read them through a loop.

answered Aug 17 '19 at 10:07

Chelmy88

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8

Thank Chelmy88 so much. Please give me some details about "through a loop" in R (functions or commands, advanced packages....). – quoc-non duong Aug 19 '19 at 01:28
What is your knowledge in R? I can show you an example, I would need to know how your files are called then – Chelmy88 Aug 19 '19 at 07:22
Hi Chelmy88, I am quite new to R. I tried rasterstack [# input=list.flies("path_to_data",pattern="*.tif$") # stack=raster::stack(input)]. But it didn't work. – quoc-non duong Aug 19 '19 at 08:42
Error in .local(.Object, ...) :
Error in .rasterObjectFromFile(x, band = band, objecttype = "RasterLayer", : Cannot create a RasterLayer object from this file. (file does not exist)
– quoc-non duong Aug 19 '19 at 08:48
Should be list.files and not list.flies, then try map <- brick(paste0("path_to_data",input[1])). What do you get. And what do you get with print(input)after running list.files (do not hesitate to add it to your question, it is more readable than in comments). – Chelmy88 Aug 19 '19 at 09:05
Thank Chelmy88, I can run. Just add "full.name=TRUE" in input=list.files("path_to_data",pattern="*.tif$",full.name=TRUE). Then # raster::stack(input). – quoc-non duong Aug 19 '19 at 14:52

Sum up rasters in R

2 Answers2