Tagged Questions

Statistical computing language and software environment.

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3
votes
2answers
193 views

How to automatically draw lines with a given angle from one single point in qgis 1.8?

I'm new to qgis so please be patient. I need to draw a bundle of lines all originating from the same point and with a 10° angle between each line (e.g. lines bearing at 0,10,20 ..90..110..220..350). I ...
2
votes
0answers
118 views

Three-dimensional interpolation of temperature profiles using gstat in R?

I'm working on a problem in which I'd like to interpolate a set of oceanographic temperature profiles over a three-dimensional matrix of unsampled x, y, & z locations. The data to interpolate is ...
6
votes
1answer
105 views

Competing approaches to line & polygon simplification

There seems to be a few theoretical options around at the moment for geometric simplification. Douglas–Peucker seems the most established, followed by Visvalingam's approach (used by d3.js). Now ...
2
votes
1answer
182 views

NDVI time series in R — how do I create a time series object from a data frame?

I am doing a time series analysis of NDVI using the bfast package in R. Bfast requires a time series (TS) object. I have successfully created a data frame with the NDVI at various point locations ...
1
vote
1answer
168 views

Interpreting Moran's I results

I have a sample of data taken from regions of a country! i want to test if there are any spatial autocorrelation on my data using Moran Indice test. the null hypothesis: is that there is no spatial ...
0
votes
1answer
108 views

How can I take a large netcdf and convert it to interpolated values in a different set of coordinates?

I've got a large netcdf (a small portion of the data is here) with the data in an even grid associated with an Albers Equal Area Conic projection. I've got the corresponding latitudes and longitudes ...
1
vote
1answer
58 views

assigning census block demographics to postal data (zip/zip+4)

Using Python and R, what would be the best strategy to tie Census Block-level data to zip/zip + 4? I understand we're not matching polygon boundaries (zip codes are not geographies), but somehow ...
0
votes
0answers
14 views

Plotting two shapefiles using R? [duplicate]

I'm not familiar with using R for GIS. I was wondering if you can help me figure out how to plot different shapefiles at the same time. I'm using the "map" function to generate a map in order to get ...
1
vote
1answer
98 views

Is there a way to write single bands raster from multi-band layer faster in r?

I have 1000 multi-layer rasters and have to export each separate layer to a tif. Some friends recommended R to do the job. I used the following code: library(raster) namesVector<- c("layer1", ...
2
votes
1answer
42 views

R - Occasional error when using alphahull package areaahull() function

I've recently started using the fantastic alphahull R package, which works beautifully most of the time but occasionally I am getting the following error when running the areaahull() function: Error ...
2
votes
1answer
71 views

How to batch generate thumbnails of raster layers with R?

I have been using R to maintain a rather large stack of raster layers (over 700 layers of data for sub-Saharan Africa). Each layer looks as follows ...
0
votes
0answers
21 views

Spatio-temporal Overlay

I have a SpatialPointsDataFrame that lists satellite-detected fires (firesutm), including location and date. I also have a SpatialPolygonsDataFrame with county boundaries (countyutm). I would like ...
1
vote
1answer
95 views

Automating Intersect between two polygon layers

I have a spreadsheet that has county-level occurrences of around 1000 species within the US in the column headings (Species State County). Thus, for some counties there may be multiple species. I ...
4
votes
1answer
123 views

Specifying Bayesian Spatially lagged dependent (SAR) variable regression in winBUGS or Stan

I have been looking for code example on how to specify a SAR spatially lagged dependent variable regression in winBUGS (geoBUGS) or, if possible, in Stan. I mean, something of the format: Y = beta_0 ...
2
votes
0answers
90 views

Ecoregions shapefiles: subsetting, extracting and summarizing data from raster

I am attempting to subset and project an ecoregions shapefile from : EPA ECOREGIONS my data set is found here: SHAPEFILES and RASTER When I run this code, two major problems occur: 1) I cannot get the ...
0
votes
1answer
73 views

Want to get an SHP file for my coutry Algeria

H everyone , i'm running a clustering test on my country with R, but the problem the clustering doen't look good because of the map i have, i hant to get a bigger map of my country 'ALGERIA' in an SHP ...
1
vote
1answer
193 views

Creating grid polygons from coordinates using R or Python

I have locational data with north-south and east-west coordinates, with a resolution of 100 meters squares. Each data point's location is somewhere within the 100 meters square which centre is given ...
0
votes
0answers
31 views

R equivalent of GRASS r.grow?

What is a good R equivalent of the GRASS function r.grow? The closest I've been able to find is the script suggested by whuber in response to Creating randomly shaped clumps of cells in a raster from ...
0
votes
0answers
70 views

how to compare multiple time series of raster files [on hold]

I am looking for the best way to compare the spatial patterns of multiple time series composed of many raster files, in R. The cell values of each raster is continuous, and I am comparing time series ...
0
votes
2answers
1k views

Return column number of min value in dataframe [closed]

So as a result of a bunch of preceding calculations I end up with a dataframe of varying numbers of rows and columns. I want to find the minimum value of the df and return the row and column index. ...
0
votes
0answers
32 views

Performing Mutiple Correspondence Analysis (MCA) using R?

I want to apply MCA (multiple correspondence analysis) to a data table containing regions as individuals, and INFESTED AREA as variable and degree infested also and the type of trees infested , and I ...
1
vote
0answers
74 views

Performing Moran Test using R? [closed]

I’m very new to R so please Bear with me: I have a set of data containing AREA Infested for each region ! and I want to know if there are any spatial autocorrelation between the regions! Here a sample ...
0
votes
0answers
31 views

Applying Spatial Clustering test using R? [duplicate]

I’m very new to R so please bear with me: I have a set of area infested by a disease (AIS) annually data and I want to apply some cluster methodology to detect regions with similar (AIS) patterns. I ...
0
votes
0answers
36 views

glm with raster data: species decline~ ndvitrend

I have species decline data (number of population per year, over a period of 23 years) out of ndvi data for these 23 years I calculated the trend, and mapped it. now i'd like to relate the negative ...
1
vote
0answers
27 views

Finding the best way to prepare raster image for a function in R

I'd like to ask what is the best way to prepare big raster images in R to run a function on whole images. I have 30 tiff images with the size of ncol=12648, nrow=4144. I read them in R separately. ...
1
vote
1answer
69 views

How to compare multiple spatial point patterns over a polygon

I have multiple point pattern distributions over the same region/polygon. Each point pattern distribution has different number of points. Here is an example of two spatial point patterns for the ...
2
votes
1answer
168 views

Running Random Forest Classification on WorldViev-2 image in R - problem

I have a problem with performing RF in R for a WorldView-2 Scene. I've never ever before used R for remote sensing classification, so I simply followed what is written here. I've loaded scene (8-band ...
3
votes
1answer
49 views

changing attributes or names of shapefiles

I am trying to join a subset of two similar shapefiles, one with states from the US and the second with provinces from Canada. The datasets are available here: shapefiles from Geocommons I noticed ...
2
votes
0answers
30 views

In R, set NA cells in one raster where another raster has values

I have two rasters in R. I want to set values to NA in the first raster where the second raster has values. I think this should be simple, using the raster package, with two RasterLayer objects ...
2
votes
0answers
82 views

R - how to create a pre-determined number of identical square polygons to use for a choropleth map?

I am trying to plot crime data density (again!) over a city map, say of NY. As a well known problem there are plenty of examples on this ...
0
votes
1answer
98 views

Test for spatial randomness with Ripley's K or L function in R

I have a spatial point pattern that I would like to test against complete spatial randomness. I managed to plot a Ripley's K function for my data and a function for a random distribution with a ...
0
votes
0answers
38 views

How to crop an image into more than 80 small sections automatically in R

I'd like to crop an image into 15 sections in R. The image projection is Geog lat/long, extending 87 to 120 degree in East and 45 to 55 degree in North. I want to separate it by every 2 degree. So I ...
0
votes
2answers
55 views

Transform coordinates from NOAA

I use data from NOAA for some analysis in R and I want to transform coordinates to EPSG:54004 or something useful. There is something what they write about their coordinates. ... POS: 29-34 ...
1
vote
0answers
48 views

Error with “lowess” function in R

I have a problem with lowess function to smooth NDVI as a time in R. Here is the scripts I run: #Create a time vector to act as x time<-sort(sample(97:297, nlayers(ndvi2000crop1))) ...
0
votes
0answers
42 views

Sextante and qgis for hotspot analysis

I want to analyze time series data for hotspot analyis. May i know whether sextante and qgis are able to generate any spatial statistics similar to Getis-O-ord in ARCGIS.Or R is required for hotspot ...
2
votes
0answers
117 views

Decision tree classification of satellite image in R

I want to classify satellite image in R using RWeka classifier, J48. I have a CSV file with the classes required, and raster data loaded in R. I am able to make the tree, however, I am not able to use ...
1
vote
0answers
61 views

Is there any issue using R scripts with sextante processing framework?

I want to use R scripts from the module Sextante treatment QGIS , but I have many difficulties to configure the module in Sextante . Following the procedure described in the official documentation of ...
1
vote
0answers
59 views

Lagrange Multiplier in lm.LMtests (spdep package for R)

Are the Lagrange values comparable in lm.LMtests? If both RLMerr and RLMlag are significant, would the test with the largest Lagrange value be considered 'better' at explaining the spatial ...
3
votes
1answer
112 views

Spatial Classification

I am not sure what to call my problem. From this image, I have a set of classified polygons (colored). I would like a way to classify the white polygons in the image. I don’t have any attributes to ...
0
votes
1answer
151 views

How can I connect my point pattern shapefile with my polygon window in R?

I would like to do some spatial statistics in R. I have a point layer called '1983' that represents the distribution of one species, and a polygon layer called 'SA-R' that represents the study area. ...
0
votes
0answers
43 views

How to predict a variable as a function of time for each land cover

I have 2 images; one is time series NDVI image (26 bands) from Apr to Oct. Another one is Land cover image with 6 classes coded form 1-5. I'd like to predict NDVI as a function of time using ...
2
votes
1answer
188 views

Convert SpatialGridDataFrame in to polygon shapefile in R

I have a SpatialGridDataFrame in R and want to plot just one of its attributes as as polygons in a GIS. There seems to be no simple way to do this. The situation is complicated by the fact that the ...
1
vote
0answers
33 views

Analyse effect of groups on raster maps

I work with a mechanistic model that uses climate data to simulate some specific output for different time steps and spatial locations. Now I want to investigate the effect of different climate data ...
1
vote
1answer
124 views

converting coordinates from unusual DMS format to decimal

So I've been shared a dataset with what to me is an unusual format for degree min second data. In their own words: The coordinates provided are longitude and latitude in degrees minutes and ...
1
vote
1answer
65 views

How to analyse point data as covariate for areal data

I have two data sets: a) a set of polygons with areal data variables. b) point measures of various co-variates of interest (note I do not necessarily have a point for each polygon) How do I ...
2
votes
2answers
647 views

Problem with merging and dissolving a shapefile in R

I am migrating from ArcMAP to opensource GIS. I've succesfully installed R and many packages in a Ubuntu 12.04 machine. I am used to linux and programming in C, but not to R and its syntax. I am ...
0
votes
1answer
120 views

Conducting geographically weighted regression on a raster

I have a relatively big raster file on which I want to conduct geographically weighted regression. Size of raster ~ 2 GB and number of rows is around 100,000 One way might be to convert from raster ...
0
votes
0answers
150 views

Unserialize socklist error when using rasterEngine in r

Basically, I am running the "rasterEngine" function in R. I want to use parallelization to change values in a raster image (I have around 400 images that I need to work on). However, the rasterEngine ...
1
vote
1answer
23 views

RasterStack extract() for duplicated dates

I have a a Large RasterStack of temperatures and a 10570 points in a Large SpatialPointsDataFrame and I'm using extract() to assign the temperatures to each point in R. ...
0
votes
0answers
17 views

Creating a loop to predict over small areas

Based on a SDM, I am I am trying to use the predict function (raster package) to predict the model to South Africa. It runs off memory and gives me an error when I predict for the entirely country, ...