Statistical computing language and software environment.
33
votes
10answers
3k 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 ...
22
votes
2answers
802 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 ...
20
votes
5answers
925 views
How to make beautiful maps in R?
There are quite some nice possibilities to analyse spatial data in R and in the context of my current project I would like to use R more frequently to do that.
Until now I plot my maps with ggplot2 ...
19
votes
6answers
2k 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 ...
17
votes
6answers
673 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 ...
16
votes
6answers
510 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 ...
15
votes
5answers
607 views
Speed of various raster data formats
I'm having trouble locating any discussion or comparative benchmarking of different raster file formats (e.g., for use in data analysis in R). Does anybody have any insight into why particular formats ...
14
votes
3answers
2k views
R to ArcGIS 9.3.1 or 10
I m trying to learn R generally and making statistics for maps. I found some useful tricks for making maps with it but it is not the best you can do. My everyday GIS program is ArcGIS. How I can use ...
14
votes
3answers
507 views
Ecological geospatial conundrum
I am looking for a different, more elegant solution to a spatial statistics problem. Raw data consists of an x-y coordinate for each individual tree (i.e. converted to a point .shp file). Although ...
14
votes
1answer
530 views
Monte Carlo simulation using QGIS and pgRouting on optimal sidewalk construction
I am new to spatial analysis and would appreciate some general direction on a project I am attempting, outlined below (I am starting from scratch).
GOAL: To find the best locations to install 2000 ...
13
votes
4answers
4k views
How to open a Shapefile in R?
I need to open a shape file from ArcMap in R to use it for further geostatical analysis. I've converted it into ASCII text file, but in R it is recognized as data.frame. Coordinates function doesn't ...
13
votes
1answer
688 views
Robust alternatives to Moran's I
Moran’s I, a measure of spatial autocorrelation, is not a particularly robust statistic (it can be sensitive to skewed distributions of the spatial data attributes).
What are some more robust ...
12
votes
2answers
481 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 ...
12
votes
2answers
347 views
Need a spatial database that can be used by QGIS and R
I'm quite new to QGIS and I'm searching for a simple way to create a Database that allows me to use the tables in QGIS and R. I have a lot of data stored in Excel spreadsheets wich will be used for ...
12
votes
3answers
274 views
How to determine if trees within forest gaps are clustered?
The attached dataset shows approximately 6000 saplings in approximately 50 variable sized forest gaps. I am interested in learning how these saplings are growing within their respective gaps (i.e. ...
12
votes
1answer
321 views
How to generalize SpatialPolygons and conserving topology in R?
I would like to generalize a SpatialPolygonsDataFrame in R to make plotting more efficient. The polygons I have result in huge pdf plots that are slow to load and hard to integrate into a document.
...
11
votes
1answer
916 views
How to create an attractive choropleth map in R?
I've been experimenting with choropleth mapping techniques in R, having reaped the benefits of ggplot2 for creating beautiful graphs within a powerful data analysis package.
When it comes to mapping ...
10
votes
3answers
499 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 ...
10
votes
4answers
676 views
Problems with NA values when reading .DEM file with R 'raster' package in Windows
I am trying to read a raster file in a .DEM format on windows using the 'raster' package in R.
I get problems with NA values, when loading the data into R in Windows 7, but I do not have the problem ...
10
votes
2answers
759 views
Using R to calculate the area of multiple polygons on a map that intersect with another overlaid polygon
I have a shapefile downloaded from the Ordnance Survey that gives electoral ward (division) boundaries for a county of the United Kingdom. I have successfully used R to load the shapefile and plotted ...
10
votes
1answer
2k 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 ...
10
votes
1answer
543 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 ...
10
votes
1answer
617 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 ...
10
votes
5answers
602 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 ...
10
votes
4answers
461 views
Does Google Maps API provide statistical tools or even raster to vector conversion?
I am working with a web developer who is working with Google maps API, trying to determine what pre-processing steps I should perform (e.g. in R and GRASS), and what can be done within the google maps ...
10
votes
2answers
161 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?
10
votes
3answers
2k 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 ...
10
votes
1answer
357 views
Spatial operators in R?
How can I do spatial selections or filters in R? I can do this in PostGIS using (e.g.):
SELECT * FROM mypoint, mypoly
WHERE ST_Within(mypoint.geom, mypoly.geom);
and it is similarly a piece of cake ...
10
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 ...
10
votes
1answer
438 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 ...
9
votes
5answers
2k 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 ...
9
votes
2answers
798 views
How to get the second nearest neighbor between two point patterns in R?
Is there a way to get the distances for the second nearest neighbor between two point patterns in R? The spatstat package has a function called nncross but it only applies to the nearest neighbors ...
9
votes
1answer
223 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 ...
9
votes
1answer
255 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:
...
9
votes
1answer
126 views
How to find the buildings (polygons) a user can see from a given location (point) and orientation (angle range)?
I would like to retrieve the set of buildings I can see from a given location (point -lat,lng) and orientation (interval of angles) + certainly with a given depth (e.g. 100 meters). Ideally I would ...
8
votes
1answer
484 views
Kriging on GRASS+R
I'm trying to do a groundwater elevation map with an Ordinary Kriging on R, but always resulting on the lack of memory
cannot allocate vector of size 146.5 Mb
allocation (windows xp 32bit). ...
7
votes
3answers
448 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 ...
7
votes
2answers
173 views
How to create a solar intensity map for a garden plot?
I'm interested in creating a raster surface that depicts the average solar intensity per unit area for a small garden plot. I imagine the inputs into the model would be the following:
Plot ...
7
votes
4answers
3k 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 ...
7
votes
1answer
225 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, ...
7
votes
2answers
236 views
Choropleth in R: custom breaks and plotting
I have a question with regard to plotting a choropleth map.
What is recommended with regard to plotting a map with custom breaks? And make it look a bit attractive.
In my script I have used the ...
7
votes
2answers
259 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 ...
7
votes
2answers
572 views
How to Find the Average Raster Value of an area defined by a shapefile using R?
I have a set of raster images which represent a specific month over the years, and I want to make a timeline of the average values of an area using a shapefile.
How do I extract the values from the ...
7
votes
1answer
1k 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 ...
7
votes
2answers
663 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 ...
7
votes
3answers
713 views
How to cluster points based on a kernel density?
I have a large dataset with 36k points representing commercial land uses, each with a field containing the square footage. I have run a kernel density analysis on this dataset, producing a raster ...
7
votes
1answer
1k views
Raster legend in R: how to colour specific values?
I have an elevation model plotted in R
r <- raster("example.dem")
plot(r, col = topo.colors(20))
Some of the values are below sea level (0), and I'd like to have those display in red. How can ...
7
votes
1answer
189 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 ...
7
votes
1answer
129 views
How to efficiently read a kml file into R
Hi I'm working with huge .kml files (up to 10 Gb) and need an efficient way to read them into R. Until now I've been converting them to shapefiles via QGIS and then back into R with readShapePoly and ...
6
votes
3answers
217 views
Classifying point coordinates to countries or continents?
I have about 50 000 points (latitude and longitude), and I would like to find out in which country each of the points is located. It does not need to be super precise, though.
(Or actually I only ...
