Coordinates tolerance Error

[Gafarou AGOUNDE]

Hi,

I am facing this error when running this code bellow;

suggested tolerance minimum: 0.662921

Error in points2grid(points, tolerance, round) :

  dimension 1: coordinate intervals are not constant

What does this error mean and how to fix it?

In fact, the Locations.csv file contains just two columns respectively X and Y in decimal degrees (e.g. X=2.07656 Y=7.08511). 

The error occurs when executing the last row.

Here is the code:

ForMapping <- read.csv("Locations.csv")

str(ForMapping)

length(PredictedAbundance) == length(ForMapping$X)

ForMapping$PredictedAbundance <- PredictedAbundance

coordinates(ForMapping) <- ~ X + Y

gridded(ForMapping) <- TRUE

Your help will be very appreciated..........!

[Bede-Fazekas Ákos]

Hello Gafarou,
the error message means that the points stored in Locations.csv are not in a regular grid, i.e., the distances between them are not the same. Although you can increase the tolerance parameter to eliminate the error message, this error usually indicate a deeper problem with the data that can not be solved (just hidden) by the increased tolerance. Maybe the points form a regular grid in another projection, so before trying to cast your SpatialPointsDataFrame to SpatialGridDataFrame with gridded<-(), you should spTransform() it to the adequate CRS. Also you should check whether the data.frame ForMapping contains all the needed X-Y pairs. If the following gives you FALSE, it may indicate the problem:
nrow(ForMapping) == length(unique(ForMapping$X)) * length(unique(ForMapping$X))
I would also give a chance to raster::rasterFromXYZ()
HTH,
Ákos Bede-Fazekas

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[Gafarou AGOUNDE]

Hi Ákos

Thanks for your contribution to my problem. However, l tried to follow your instructions but l can't because I'm not too comfortable with R language.

Could you proposed me anoter simple alternative ?

Best

Management of Wildlife, Protected Areas and Rangeland | MSc, University of Abomey-Calavi, Benin republic. Phone number:(+229)96692934

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