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3
votes
1answer
291 views

Sample size for variogram modelling using the geoR package in R

I am trying to use the geoR package in R to model the variogram for a dataset of 15 000 sample points of bathymetry data. I intend to do a random split to create test (20%) and training samples (80% ...
2
votes
1answer
282 views

R or QGIS? Measuring elevation at points on DTM surface

Based on answers to this recent question I have been able to create natural looking digital terrain models using a combination of raster, rasterVis and rgl working on data held in ESRI ASCII grid ...
0
votes
1answer
111 views

Can rgdal use an external GDAL installation?

The README for rgdal contains the following text: file.show(system.file("README", package="rgdal")) For additional drivers, users of the CRAN Windows and CRAN OSX binaries can either convert ...
3
votes
0answers
459 views

Novel ways of filling in missing values in a raster

I am looking for robust ways to fill in missing values in some rasters. They all have a single layer. Missing values consist of single pixels to medium sized patches. Rasters are around 1000 x 1000 ...
5
votes
4answers
1k views

Calculating percent cover from shapefiles

I normally do not work with shapefiles, so I am a bit lost here. I have two shapefiles each with multiple objects. The first is a set of 32 polygons (each one is a plot). The second shapefile has ...
2
votes
1answer
202 views

Axis of rendered shape files not showing numbers that are latitude and longitude

I am using rgdal to render some shape file. The first is a set of building zones from NYC Open Data. The second is the NYC coast line from OSM. The Zone files seems to generally render an X axis ...
3
votes
2answers
346 views

Is there a way to speed up gIntersections for large spatial objects?

I'm attempting to perform a gIntersection of a big grid on a shapefile for country boundaries, so that I can calculate the % area of each grid cell that lies within the country. It takes a few seconds ...
2
votes
2answers
296 views

How to find the second highest value in a rasterStack in R

I have a rasterStack of rasters representing count data. I want to return a single raster whose values are the index of the raster with the second highest value for each cell. (I used which.max for ...
2
votes
1answer
159 views

R - Efficient way to segment rasters into sub-regions and sample… without using extract()

My question is: Is there a more efficient way to sample from a sub-region (defined by a shapefile read into a spatial object) of multiple rasters without having to use extract() for each region on ...
4
votes
1answer
457 views

ggmap, ggimage… - Saving and loading maps in R

In my current R project I'm working with the ggmap package to download and display maps. What bothers me is that you need internet access to load maps from google etc. I'd like to load a map from the ...
1
vote
1answer
421 views

How to do geometric correction of remote sensing data in R?

My challenge is to replace most of the remote sensing commercial tools with R code (I'm teaching assistant at the University and I would like to move to open source R code to show the added values to ...
2
votes
2answers
349 views

How to use ggplot with Processing in QGIS 2.0?

I'm trying to use R scripts within QGIS thanks to Processing. There are some example scripts available and I achieved to plots different columns of the attribute table (with the plot built-in ...
0
votes
1answer
554 views

Scale parameter of the GetMap function within RgoogleMaps

Within the R library called "RgoogleMaps", there is a function called "GetMap" which is used to save a georeferenced image file. The library's manual suggest that the SCALE parameter supposed to be ...
1
vote
0answers
104 views

Making spatial clusters by direct manipulation of raster pixel values using R

I think this is an overambitious million dollar question, but I'm always optimistic when I pose a question even though I feel like I left no stone unturned! I've processed a raster layer with pixel ...
4
votes
2answers
612 views

Convert polyline shapefile to points 1m apart and add xy coords in R

I have a table with xy coordinates in R and the following packages loaded: spatstat, raster, rgdal, sp and zoo. I do know how to use this to make a point shapefile, a line shapefile that goes through ...
7
votes
3answers
763 views

R - How to sampleRandom() from large raster without NA values

I have a number of vary large rasters which need to be randomly sampled with the return value being a matrix of x, y, and value. The raster package sampleRandom(raster,n, na.rm=TRUE, xy=TRUE) will do ...
1
vote
1answer
646 views

add unique IDs to mutiple polygons using loop or apply function

I want to add a unique ID (row number) for each polygon in a SpatialPolygonsDataFrame. I'm new at working with spatial data (and programming) so bear with me please. The goal is to merge all polygons ...
2
votes
2answers
832 views

Plotting a map of New Zealand with regional boundaries in R

I have been asked to make a map of New Zealand using R with regional boundaries. I need something exactly like this example of a map for Switzerland: ...
4
votes
1answer
2k views

R - Plotting shapefile with geographical (raster) data

Over the last few days I have been trying to plot a shapefile over data loaded into a data.frame within R. It should be a view of radar precipitation with an overlay of the country borders from a ...
4
votes
2answers
103 views

towgs Definition for European Datum 1950

I am new to all things GIS so apologies for a basic questions. I am trying to specify the CRS of a climatic raster layer in R. It is an equal area projection based on Europe Equidistant Conic and the ...
1
vote
2answers
2k views

Calculate distance in kilometers between two points

I have a few questions regarding the calculation of the distance between 2 postal codes. Take a look at the following code. ### # load the different packages we need ### require("rgdal") ...
0
votes
1answer
304 views

Update GEOS to 3.4

I want to use the rgeos function gDelaunayTriangulation (which requires GEOS 3.4) on my Mac, but when I load rgeos it says: > library(rgeos) rgeos version: 0.3-2, (SVN revision 413M) GEOS runtime ...
3
votes
1answer
72 views

How to re-ID polygons with sapply instead of for loop

I have a line of code that renames the id's of polygons in a SpatialPolygonsDataFrame by directly manipulating the ID slot of the polygon. I'm a bit slow when it comes to sapply, having used for loops ...
2
votes
0answers
158 views

Joining nearest neighbor small polygons using R

The figure shows a plot of numerous polygons (zoom in) made from a raster file by require(sp) require(raster) pol100 <- rasterToPolygons(r, fun=function(x){x==1}, dissolve=FALSE) There polygon ...
3
votes
2answers
525 views

Replicating QGIS style in R with rgdal

I want to use rgdal to plot a shapefile graduating the colour of features according to the values of one field (density). I couldn't find online detailed indications on how to do it and the package ...
3
votes
1answer
33 views

Equidistant projection for northern Delaware

I'm just getting started on a long-term project involving northern Delaware. Most of my distances will use great circle distances from the lat/lon, but for a few applications I'll wind up using ...
3
votes
2answers
1k views

Efficient way to handle NA values from analysis in R with Raster

I am not 100% sure if GIS is the correct stackexchange for this, but here we go. A problem I have been bested by: I have a raster layer of approximately 240 million cells. It could be a DEM or ...
1
vote
1answer
171 views

Mapping variables based on STFID values

This quest is an extention of a question that I made earlier today but since it's migration to GIS I haven't been able to comment on my older post. My earlier post is : Mapping Kansas City based on X ...
4
votes
1answer
780 views

How do I implement 'weighted' kriging in R?

I'm trying to interpolate the values of an attribute (called "disease_rate") that i've sampled at a set of spatial points and i'd like to add 'weights' to the resulting kriging estimates. Basically, ...
1
vote
0answers
164 views

Mapping Kansas City based on X and Y Coordinates in R

I have a csv file in R that has coordinates of Kansas City, however, the values at these points aren't in any traditional longitude/latitude formatting that I am aware of. My data looks like this: ...
3
votes
1answer
252 views

Fix Labels United States Map Help R, R-Studio?

Does anyone know how to deal with the labels that do not fit within a states boarders? I need the labels on the east coast to be moved outside of the state and a line drawn pointing to the ...
2
votes
1answer
431 views

Choosing correct proj4string in R for a set of points

I was given a set of points which I eventually will overlay with a polygon shapefile in R. The issue is that the person who provided me with the points did not give them to in long/lat coordinates but ...
4
votes
2answers
196 views

Problem overlapping shapefile and vector in R

I want to plot a shapefile over a raster file in R but I can't make them overlap perfectly: the raster appears to be rotated of few degrees counter-clockwise. Is it a problem with the projection? ...
0
votes
1answer
104 views

How can I export a point shapefile from ArcGIS to R

I am having several problems in exporting my point shapefile from ArcGIS 10 to R. I tried to save the shapefile as a CSV, but R reads all in one row; somebody in another question answered to use ...
2
votes
1answer
361 views

Convert multiple Shapefiles in Raster in R(and then plot it)

I'm trying to convert several shapefiles in rasters at the same time. I already was able to read the shapefiles by doing this: library(maptools) shps <- dir(getwd(), "*.shp") for (shp in shps) ...
10
votes
1answer
454 views

How do I randomly alter a raster map of habitat types?

I have a raster of habitat types for a specific area in Scotland. I need to create future habitat scenarios with changes in habitat to assess the population viability of a bird species. For example, ...
2
votes
1answer
849 views

Population density map

I have California population density data from from the U.S. Census in an Excel file. The spatial information is provided in ZIP Code Tabulation Areas (ZCTAs). How do I plot a population density map ...
1
vote
1answer
405 views

How to get custom color palette in rasterVis plot3D in R?

I am trying to insert an RColorBrewer palette to visualize an elevation raster in R using the rasterVis function plot3D. The rasterVis reference document shows the following parameters: plot3D(x, ...
1
vote
1answer
147 views

Retrieving the proportion of specific pixel class from CHM rasters

CHM = canopy height model I am very new to R (specially for GIS purposes) and I am struggling a bit in getting the following pixel statistics: Proportion of zero value pixels = [nº of zero value ...
1
vote
1answer
462 views

Buffer analysis - use of surface area based on DEM

I have one problem and this is that I would like to create a buffer around point. This is simple with ArcMap using the buffer tool. But is it possible to create the buffer considering also the true ...
0
votes
1answer
137 views

How long should it take to load a point layer with readOGR? [closed]

I am afraid I am quite new to spatial analysis at anything beyond a superficial level, and I have only recently transitioned to utilizing R. I have been quite pleased with the versatility of areal ...
0
votes
0answers
28 views

calculating mean and standard deviation for raster values using whole pixels within a polygon [duplicate]

i have a raster image and a corresponding shape file. i would like to calculate the statistics of the values within polygons which have a common attribute but only using pixels which are fully ...
3
votes
2answers
246 views

How to do regression analysis out-of-memory on a set of large rasters in R?

I am trying to do a regression analysis on a set of large rasters (254,004,000 cells each). Ultimately, I want to run something like the following (or a bit more complex, but let's start simple!): ...
3
votes
0answers
600 views

Fortifying re-projected shapefile for ggplot2 in R

I have a shapefile of US county boundaries which I got from the NHGIS. I can load the file using the rgdal package and see information about it: library(rgdal) shp_1860 <- readOGR("shp", ...
3
votes
0answers
388 views

R with ggplot2/ggmap - How to load a png image as a map

I am trying to find a workaround for ggmap's missing support of world maps (i.e. you can't create any maps that show latitudes > 80°, due to idiosyncrasies in the mapproj package). To a limited extend ...
3
votes
1answer
403 views

How to link R script to Algotithm output in QGIS modeler?

I constructed a simple R script for QGIS modeler (.rsx) that calculates groupwise summary statistics of a vector layer table (sum by field "subject" and "FRC"). The script correctly works. When ...
0
votes
0answers
247 views

why readOGR() is not reading projection information from .spj - r

0 down vote favorite I successfully import a polygon shapefile with readOGR, however the information in the .prj file is not being imported. test class : SpatialPolygonsDataFrame nfeatures : 19407 ...
2
votes
0answers
379 views

R, GeoJSON and Leaflet

I recently learned about leafletjs.com from an R-Bloggers.com post. One such tutorial that I would like to achieve is to create interactive choropleth maps with leaflet. I have been using the rjson ...
5
votes
1answer
382 views

Why does ManageR and rpy2 not work in QGIS (1.8.0-Lisboa)?

I have been trying to get R scripts to function and ManageR to work within QGIS (1.8.0-Lisboa). (Windows 7). Python2.7.5. Two problems indicated that R was not working in QGis. First - when I run an ...
2
votes
2answers
470 views

What is faster for geoprocessing (intersect) big shapefiles?

I have 200 Mb shapefiles of polylines downloaded from OSM. I've been working with QGIS 2.0 in Ubuntu 64 Bit 8 Gb RAM to make some geoprocessing tasks and it's taking 2 days for processing. Once I've ...