Statistical computing language and software environment.

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1answer
150 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 ...
4
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2answers
62 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 ...
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1answer
138 views

Calculate area covered by a particular raster layer within polygons in QGIS

I am trying to extract information on vegetation cover within a set radius of point locations (my sites). I have succeeded in creating a new vector layer of circles with a 5 km radius around my sites. ...
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2answers
222 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") ...
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1answer
88 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 ...
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1answer
55 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 ...
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2answers
187 views

Calculate a polygon around a point - and conver to WKT

The use case I have is this: I want to take points (in my case a data.frame of lat/long coordinates) and calculate a polygon around each point of a given radius (in km, miles, whatever). To be clear, ...
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0answers
93 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 ...
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1answer
435 views

How to make RASTER from irregular point data without interpolation

I was trying to make a raster image from an irregularly spaced point database. The data looks like- > head(s100_ras) x y z 1 267573.9 2633781 213.29545 2 262224.4 2633781 ...
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1answer
52 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 ...
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1answer
22 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 ...
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1answer
85 views

R for loops in Geospatial modelling environment

I am using the isectpolypoly command in GME and would like to iterate over several polygons ("proj_0_ect0207", "proj_1_ect0207"). My code is as follows: for (i in 0:30) { ...
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2answers
92 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 ...
4
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1answer
124 views

Loading a multipoint shapefile in R

This issue has only been raised in the community once, two years ago, to the best of my knowledge. I think it's high time to raise the issue again! readOGR, from the rgdal package, cannot handle ...
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1answer
92 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 ...
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0answers
81 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: ...
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2answers
223 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 ...
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2answers
258 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 ...
2
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1answer
75 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 ...
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1answer
151 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 ...
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1answer
174 views

Spatial Interpolation - defining a minimum value for agroup of points

I am doing spatial interpolation with a group of points. Some points have complete observation of events: for a period of 24 hours we have observed N events in each point. These points have N ...
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2answers
112 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? ...
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1answer
60 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
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1answer
112 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) ...
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1answer
71 views

How to analyze and combine overlaping elevation maps into one?

I have 30 overlapping maps that contain tree density heights (measures between 1-100%) of a large area, and I need to get the highest point by pixel and create a new map with all these highest points ...
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0answers
104 views

Interpolate/disaggregate point values to an existing raster grid

I have several thousands of ASCII files whose names have the following format: data_"lat"_"long".mon (e.g. data_41.21875_-116.21875.mon). Each file represents one point in WGS84 projection and the ...
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1answer
225 views

Can't plot polygons with R and ggplot2

I am new to shapefiles so I maybe ask some stupid questions, sorry. I want to plot a map of my region, with colour filled polygons using R. I have downloaded municipal (lines) and province (polygons) ...
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1answer
165 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, ...
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2answers
477 views

Resources on using R in QGIS for R users?

This is a very basic question, but I'm having a heck of a time figuring it out because so much of the QGIS documentation is oriented toward use of the GUI. I want to be able to run R scripts in QGIS, ...
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0answers
81 views

Spatio-temporal prediction with KrigeST in R

I'm new in R and ST kriging, I've constructed a STFDF object with the first 4 hours historical data, and want to forecast the fifth hour data. By using krigeST in R, I've constructed vgm model. But ...
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1answer
144 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 ...
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2answers
236 views

Simple way to detect/select border polygons of a shapefile

I am looking for a simple way to detect/select border polygons of a shapefile. Border polygons are here polygons that are not completely surrounded by other polygons i.e. polygons located at the ...
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0answers
24 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 ...
0
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1answer
166 views

How to access each raster in a stack with a loop

I have a stack of rasters and I want to access each layer, combine each later with another file and finally export the resulting file as a csv file. Is there any way to do this with a loop? So far I ...
3
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0answers
223 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", ...
2
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1answer
393 views

Is it possible to create and run custom R scripts in QGIS 2.0?

I am new to QGIS and most of the tutorials I have found are for 1.x and the overhaul has me confused. I would like to create R scripts and run them in QGIS. I have read here that it's possible using ...
3
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0answers
183 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 ...
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1answer
237 views

r openproj to plot in open street map in a different projection

I am very new to geographic data, so I am sorry for the stupidity of the question. I need to plot some data that are in this projection EUREF_FIN_TM35FIN Projection: Transverse_Mercator ...
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2answers
225 views

How to create random point in according polygon for each dataset entry in a list (with R)

I have an area divided into polygons, and a dataset of observations which has a common field with the polygon layer. I now would like to generate a random point for each dataset entry within the ...
0
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0answers
93 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 ...
5
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1answer
160 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 ...
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2answers
256 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
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1answer
237 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 ...
4
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1answer
394 views

Shortest distance from point to line (big dataset)

What is the best method to calculate the distance from the nearest road for a series of address points in QGIS, having a very big dataset? (QGIS 2.0.1, Win XP) I read the answers to previous similar ...
3
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1answer
318 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), ...
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1answer
70 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), ...
3
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1answer
106 views

Given a Lat and Lon, identify if the point is over land or ocean?

In R, what is the quickest way to identify if a point is over land or ocean? e.g. for: set.seed(0) lat <- runif(10, -80, 80) lon <- runif(10, -180, 180) points <- expand.grid(lat, lon) ...
3
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3answers
145 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 ...
5
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1answer
143 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( ...
4
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1answer
172 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 ...