[R-sig-Geo] How to adjust two maps with different extent in R

Nahm Lee nlee at valleywater.org
Mon Dec 19 08:21:40 CET 2016


spTransform(ws_soil,CRS=CRS("+proj=longlat +ellps=WGS84 +pm=+360 +datum=WGS84 +no_defs"))

You need to play with "+pm=+360"

-Nahm Lee

-----Original Message-----
From: R-sig-Geo [mailto:r-sig-geo-bounces at r-project.org] On Behalf Of Zhang Tianyi
Sent: Sunday, December 18, 2016 10:51 PM
To: r-sig-geo at r-project.org
Subject: [R-sig-Geo] How to adjust two maps with different extent in R

Two maps with different extents

I am using R to process two maps (raster package). I have two maps with both WGS84 coordinates see figure. [image of map] <https://i.stack.imgur.com/bD84y.png>

But one layer is from -180 to 180 in longitude (the map on surface) another one is from 0 to 360 (the map on the bottom).

I need to adjust the bottom layer to -180 to 180 so that they can match. How can I do that?

I think I need to find all grid greater than 180 and then minus 360. But I cannot find the longitude vector and cannot modify it from the Raster data.

Description of the map is:

class       : RasterLayer
dimensions  : 94, 192, 18048  (nrow, ncol, ncell) resolution  : 1.865234, 1.883872  (x, y)
extent      : 0, 358.125, -88.542, 88.542  (xmin, xmax, ymin, ymax)
coord. ref. : +proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0 data source : in memory
names       : TMAX_2015_01_01
values      : 220.9, 324.3  (min, max)


Regadrs,
Tianyi Zhang

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