Statistical computing language and software environment.

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11
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3answers
893 views

How can I generate irregular grid containing minimum n points?

Given a large (~ 1 million) sample of unevenly distributed points - is it possible to generate irregular grid (in size, but could also be irregular in shape if that is possible?) that will contain ...
13
votes
2answers
3k views

How can I convert data in the form of lat, lon, value into a raster file using R?

I have a data set of values over a km grid in the continental U.S. The columns are "latitude", "longitude", and "observation", e.g.: "lat" "lon" "yield" 25.567 -120.347 3.6 25.832 ...
5
votes
4answers
2k views

How to split a vector in equal smaller parts in QGIS or similar?

i want to divide a shapefile with many tiles into a lot of smaller tiles. I am searching for a smart solution, because manual edits are out of questions Anyone can help or know a nice function?
11
votes
6answers
883 views

How to implement value-by-alpha map in GIS?

I've been doing some background reading about cartograms recently and stumbled upon interesting alternative - value-by-alpha maps. Concept is described in more details here and full paper is ...
23
votes
7answers
3k views

How to compare two spatial point patterns?

If I have two point pattern distributions within the same geographic region, how would I go about visually and quantitatively comparing those two distributions? Also assume I have many points within ...
12
votes
2answers
2k views

Raster noise reduction and edge smoothing

I have a raster image like this I want to delete the isolated noise point and smooth the edge (say the white single points, and I want the edges of the entity look smooth). How can I do this in ...
10
votes
1answer
460 views

How to visualize azimuthal data with uncertainties?

I am trying to make a figure showing azimuthal data with a different range of uncertainties at each point. This oldschool figure from a 1991 paper captures the "bowtie plot" idea that I'm aiming for: ...
38
votes
10answers
4k views

What is the most useful spatial R trick?

R is becoming pretty strong tool for handling and analyzing spatial data. I learned some useful things through questions like these at SO and thought it might be useful to have something simmilar, but ...
18
votes
6answers
632 views

What are sources for current geo-statistical analysis classes/events: open or proprietary

I am keenly interested in geo statistics (and many other words with 3 t's :). I am not very programatically inclined but have been following several lists with this theme. One being the R filter on ...
8
votes
1answer
362 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, ...
4
votes
2answers
558 views

QGIS affine - form of equation

I am at the mercy of a govt authority who have provided utility information in a cad format with a 0,0 origin and a nonsense grid. About a dozen files, the grid and origin are entirely arbitrary. To ...
4
votes
1answer
825 views

Superimpose grid on points, then aggregate points within each grid cell

I have a vector of presence/absence values (1,0) and a matrix of x,y coordinate data (projected) specifying the spatial position of each value (about 25,000 in total). I'd like to aggregate the point ...
11
votes
1answer
1k views

Random sampling of raster using R

Is there a straightforward way of randomly sampling a raster so that the output of the process is a raster? I'm using an example that I found on the r-sig-geo list and I have also tried the ...
11
votes
1answer
2k views

Projecting sp objects in R

I have a number of shapefiles in different CRSs (mostly WGS84 lat/lon) that I'd like to transform into a common projectly (likely Albers Equal Area Conic, but I may ask for help on choosing in another ...
7
votes
1answer
750 views

Removing rows in shapefile in R

I've imported a shapefile into R, and joined it to a table. My shapefile contains all the census ids, while my table only contains selected census ids. I'm now trying delete all the rows didn't get a ...
9
votes
3answers
3k views

Which is the best way of working with PostGIS data in R?

I work with R almost all the time, and now I am using it for doing spatial data mining, but I have this question: I have a PostGIS database with (obviously) GIS data, If I want to make statistical ...
9
votes
1answer
2k views

Instantiating spatial polygon without using a shape file in R

So, the usual way we read a shapefile in R is via the maptools package, like this: sfdata <- readShapeSpatial("/path/to/my/shapefile.shp", proj4string=CRS("+proj=longlat")) However, I have a use ...
8
votes
2answers
2k views

Clipping a raster in R

I am building a map for the northeastern U.S.A. The map background needs to be either an altitude map or a mean annual temperature map. I have two rasters from Worldclim.org which give me these ...
6
votes
2answers
290 views

Creating randomly shaped clumps of cells in a raster from seeds of 1 cell/pixel?

As my title says, I wish to "grow" clumps of cells from seeds within a raster. My base raster is full of 1's and 0's, 1's indicate land and 0's sea/NA areas. From the 1's I wish to select 60 random ...
6
votes
2answers
1k views

creating a raster of the residuals of a regression between two rasters

I am trying to create a raster of the residuals of a regression between two rasters. i.e. I would like to carry out a regression of one raster against another of the same extent and plot the residual ...
2
votes
2answers
905 views

How to create a map with states by attribute value?

I'm using Qgis, but I am quite familiar with R and python. So I could use any of these. I want a map of mexico but want to color the stats according to a certain variable. It goes from 0 to 100. So ...
11
votes
5answers
3k views

Get Raster Values from a Polygon Overlay in Opensource GIS Solutions

I have two layers. A polygon-shape-layer with many tiles and a raster-layer containing CORINE 2006 land cover with many categories in a colourmap. I want to obtain for each polygon in the shapelayer a ...
6
votes
2answers
988 views

How to extract values from rasters at location of points in R?

My question is about extracting values from rasters at the location of points. With the function extract this is very easy, and the function gives me a dataframe with the values of all the variables ...
6
votes
4answers
9k views

How to convert zip codes to latitude and longitude?

I have a data set that includes a list of zip codes. Is there a way in R to convert these zip codes to latitude and longitude coordinates?
7
votes
3answers
537 views

How can I make a county-level shape file from a set of points at 30 x30 km spacing?

I have a data set in csv form, like: latitude, longitude, value -45, 45, 10 .... I would like to calculate county level means from these data, using either ArcGIS or R+grass. I have the ArcGIS USA ...
5
votes
2answers
757 views

How to implement bivariate Ripley's K function in ArcGIS 10?

The attached image shows a forest gap with red pine represented as circles and white pine represented as crosses. I am interested in determining if there is a positive or negative association between ...
3
votes
1answer
173 views

remove land area from marine region polygons

In my pursuit to merge multiple polygons for the purpose of calculating the surface area of marine species distributions, using shapefiles from Marineregions, I am now trying to remove potential land ...
4
votes
2answers
382 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 ...
4
votes
2answers
623 views

How to calculate area of 1 x 1 degree cells in a raster

I have a simple array (not geo-referenced in any way) in Matlab (which is not a language I know a huge amount about...so I can export it to other languages if needed) which has the dimensions 180 x ...
4
votes
3answers
975 views

How can I find out how to convert this point to lat lon?

I have received a shapefile with measurement points to be analyzed, but no matter how I try, I can't find how to convert to lat lon. I suppose it would be good to know the projection but when I look ...
0
votes
2answers
85 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 ...
23
votes
6answers
4k views

Tutorials to handle spatial data in R

Does anyone know some good tutorials to handle spatial data in R? I know that there are some packages like rgdal and maptools but I haven't actually found usefull tutorials to get in touch with the ...
26
votes
2answers
2k views

How can I conduct Geographically Weighted Principal Component Analysis using ArcGIS, Python and SPSS/R?

I am after a description/methodology for conducting a Geographically Weighted Principal Components Analysis (GWPCA). I am happy using Python for any portion of this and I imagine SPSS or R being used ...
10
votes
1answer
1k views

How to perform Random Forest land classification?

This is a follow-up to a previous post: Machine Learning Algorithms for Land Classification. It seems that the Random Forest (RF) classification method is gaining much momentum in the remote ...
13
votes
4answers
4k views

How to cluster spatial data in R?

I am very new to R, so please bear with me : > I have bunch of data points with latitude and longitude. I want to use R to cluster them based on their distance. I have already taken a look at this ...
6
votes
1answer
839 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)) ...
4
votes
1answer
470 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, ...
11
votes
1answer
2k views

Using R with ArcGIS Desktop

In response to comments below, a re-phrasing of the question. I've used the integration of R with QGIS, and found it a very uesful tool. Having taken a look at the R toolbox extension for 9 and the ...
9
votes
1answer
264 views

How to find the most spread out locations?

Probably a very simple question. I have a list of about a thousand potential geographical locations (lat lon), and of those I need to select the 200 locations that are "most spread out". I think that ...
8
votes
3answers
169 views

R, rasterVis and RGL: how to prevent reflective surfaces?

I have been experimenting with digital terrain model files in ESRI ASCII grid raster format. Despite zero experience with this type of data I found it very easy to load into R, as per code below. The ...
10
votes
2answers
229 views

Count raster value in a bounding box (spatial extent)

I have simple question: given a bounding box, how can I count the number of specific values (say, I am interested in the number of value == 1 ) in a raster in 1) arcpy, or 2) raster package in R?
7
votes
1answer
680 views

How can I use fortify() to create a filtered R data frame from a shape file?

I am in the process of building a ggplot choropleth map of population in administrative areas in Wales. I have downloaded the Boundary-Line data from the Ordnance Survey and extracted what seems to be ...
7
votes
2answers
814 views

Is it possible to run an R script on a layer in QGIS?

I'd like to run an R script on a layer loaded in QGIS (to rotate a set of points created there using the Vector:Research Tools:Regular Points tool). I thought ManageR might work but cannot get it ...
6
votes
1answer
2k views

GIS, R and shapefiles

I have some data that encodes locations in certain countries, such as the US and China, that I would like to map. The data includes location name in Latin, extended Latin and other scripts (Japanese, ...
5
votes
1answer
9k views

find the centroid of a cluster of points

While searching the web, solutions for finding centroids of polygons come up rather often. What I'm interested in is finding a centroid of a cluster of points. A weighted mean of sorts. I would ...
9
votes
2answers
1k views

Aggregating points to grid using R

I have a question with regard to spatial aggregation in R. What I am trying to do is aggregate a point dataset to a grid. I am unsure however how to do this as I have little experience with this sort ...
8
votes
3answers
549 views

Identification of consecutive points within a specified buffer

I have a point file, hourly relocations of an animal, and I want to be able to place a buffer around each point and calculate the number of subsequent points which are within the buffer zone. I am ...
8
votes
3answers
2k views

R: Download a large DEM, change projection, and adjust to smaller scale

This is a process that takes just a few seconds in GIS software. My attempt to do it in R uses a large amount of memory then fails. Is there something wrong in my code, or is this just something R ...
7
votes
4answers
5k views

How can I export raster data from Arcmap to an R *.grd file format?

I want to work with raster data in R, but I have problems exporting my raster dataset from ArcMap. By "export data"/GRID I get a file with an *.aux extension. What I need is *.grd. Can anybody help ...
4
votes
1answer
502 views

Self organizing maps and spatially Constrained Clustering in R

There are a few algorithms to perform spatial clustering in R but most of them focus on point pattern analysis (for example here). I would like to perform spatial constrained clustering for polygon ...