Message-ID: <01C90C14-9359-4159-BF9E-50FC7DA64EAE@bigelow.org>
Date: 2016-02-17T02:47:37Z
From: Ben Tupper
Subject: Calculate percent cover in a raster
In-Reply-To: <69556754.4238749.1455673908362.JavaMail.yahoo@mail.yahoo.com>
Hi,
I think you can use raster::reclassify() or raster::cut() to bin your rainfall.
intervals <- seq(from = 0, to = 600, by = 100)
ix <- cut(r, breaks = intervals)
tx <- table(as.vector(ix))
tx
1 2 3 4 5 6
46 64 85 76 100 69
tx/sum(tx)*100
1 2 3 4 5 6
10.45455 14.54545 19.31818 17.27273 22.72727 15.68182
Is that what you are looking for?
Cheers,
Ben
> On Feb 16, 2016, at 8:51 PM, Thiago V. dos Santos <thi_veloso at yahoo.com.br> wrote:
>
> Hi all,
>
> I have a raster at 0.5 degree resolution with monthly totals of rainfall, which range from 50 mm to 600 mm:
>
> require(raster)
>
> ## scratch a raster and fill some random values
> r <- raster(nrows=22, ncols=20, xmn=-58, xmx=-48, ymn=-33, ymx=-22)
> r[] <- round(runif(22 * 20, min=50, max=600), digits=0)
>
>
> How can I calculate the percentage area of the raster covered with some rainfall ranges?
>
> Let's say for example 0 to 100, 101 to 200, 201 to 300, 301 to 400, 401 to 500 and finally 501 to 600 mm?
> Thanks in advance,
> -- Thiago V. dos Santos
>
> PhD student
> Land and Atmospheric Science
> University of Minnesota
>
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Ben Tupper
Bigelow Laboratory for Ocean Sciences
60 Bigelow Drive, P.O. Box 380
East Boothbay, Maine 04544
http://www.bigelow.org