Statistical computing language and software environment.

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4
votes
2answers
570 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
721 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
605 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
743 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
101 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
1k 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
286 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
71 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
155 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
499 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
31 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
165 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
735 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
157 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
233 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
389 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
187 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
101 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
353 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
447 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
787 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
378 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
145 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
446 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
129 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
232 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
575 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
355 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
392 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
223 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
363 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
372 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
445 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 ...
2
votes
1answer
362 views

Tearing in ggmap (R) after using spTransform and random point generation using splancs

I am using R and the package ggmap to try and generate some random points within the city limits of Chapel Hill, NC. I have downloaded the shapefile for the town of Chapel Hill from the Orange County ...
7
votes
1answer
1k views

use proj4 to specify Robinson projection with R ggmap and ggplot2 packages?

I want to project this map in robinson projection: library(ggmap) world <- map_data("world") ggplot() + geom_path(data = world, aes(long, lat, group = group)) ...
2
votes
1answer
576 views

How do I convert longitude & latitude to a 3d (geocentric x,y,z) coordinate?

I'm interested in finding the centroid of a point cloud. I understand that to do this I need to convert latitude and longitude values to 3d coordinates, average them and then convert the resulting ...
3
votes
1answer
955 views

Layer map plots on top of one another in R/ggplot2

I'm making a choropleth map in R/ggplot2. I have the colored part working just fine. This code p <- ggplot() + geom_map(data=c_1860, aes(map_id = GISJOIN, fill = AHL002), ...
4
votes
1answer
374 views

How to join data from NHGIS to make choropleth maps in R/ggplot2?

I have downloaded shapefiles of county/state boundaries and census data keyed to those shapefiles from the NHGIS. Both the shapefiles and the census data have a GISJOIN column to be used for merging ...
3
votes
3answers
281 views

programmatically add field to shapefiles and insert shapefile name in every row of field

situation We have a folder containing 1 sub-folder for every participant in a study. The subfolders are named with the participants' ID, e.g., 1000, 1001, 1002, 1003. Every participant folder ...
0
votes
1answer
230 views

How to convert 'RasterBrick' object to 'im' object in R?

During script execution I need to convert 'RasterBrick' to 'im' object. Package 'geostatsp' is supposed to do this job: library(geostatsp) myraster = raster(matrix(1:100,10,10), ...
0
votes
2answers
191 views

How can I fix a geoTiff with an incorrect CRS?

Trying to load and plot a raster (it's a DEM) in R, but having problems. Using R I read in a raster file: library(raster) dem <- raster("DEM_Victoria.tif") # >70 MB print(dem) class ...
4
votes
2answers
781 views

What is the cause of 'tearing' of polygons (artifacts) using R, ggplot and geom_polygon?

Thanks to the answer given in this question I have been able to subset and draw a map of electoral divisions in part of the UK, in this case Pembrokeshire. The resulting data frame is large and ...
5
votes
1answer
441 views

Legend of a raster map with categorical data

I would like to plot a raster containing 4 different values (1) with a categorical text legend describing the categories such as 2 but with colour boxes. I've tried using legend such as : legend( ...
3
votes
1answer
482 views

Change Circle Size According to Value using R

How do I change circle size in a population map according to the population density of the location? library(maptools) library(RColorBrewer) library(classInt) library(maps) ## load the file ## pop ...
0
votes
1answer
1k views

How to count number of polygons inside another polygon layer?

I am looking for a tool in arcgis 10.1 Qgis or R that allows me to count the number of polygons that are inside specific areas (defined also as polygons). My data consists in: 1 shape file with ...
2
votes
2answers
700 views

Using Regression Trees in ArcGIS

Hi I have a follow up question to this post: Statistical analyses for survey against raster? I have a very similar problem as the initial poster David. I am creating a multivariate model from ...
1
vote
1answer
155 views

Extract polyline of border between differing polygons

I have a shape file with polygons with an associated variable that can take different values. I would like to extract the borders between polygons of differing value (red and blue) as a polyline (dark ...