Questions tagged [r]

Statistical computing language and software environment.

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5
votes
2answers
5k views

How to calculate distance from POINT to LINESTRING in R using `sf` library and get all POINT features from LINESTRING where distances were calculated?

I'm trying to calculate distances from a set of POINT features (1, 2, 3, 4, 5, 6 & 7) to a LINESTRING feature using sf library in R. I could calculate all the distances using the function ...
4
votes
1answer
706 views

MOD09A1 QC layer

Does anyone know how to handle MOD09A1 Quality flags (QC) in in R? I was trying to use raster package but unable to unlock the QC band.
9
votes
3answers
14k views

Converting point to lat lon? [duplicate]

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 ...
1
vote
1answer
4k views

How to rasterize a vector dataset in R?

I would like to compare vector vs raster data. So i try to fix a problem using both ways. I made it in vector first : coastline<-readShapeSpatial("shp") wets<-readShapeSpatial("shp") wetb<-...
32
votes
2answers
6k 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 ...
14
votes
2answers
11k 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 ...
14
votes
2answers
30k views

Choosing the correct value for proj4string for shapefile reading in R?

I am having a shapefile of polygons and another CSV file which contains a list of points as (Lat, Lng) pairs.. I want to check for each (lat, lng) pair from the CSV file which polygon does it fall ...
13
votes
2answers
5k 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 ...
17
votes
6answers
30k views

how to overlay a polygon over SpatialPointsDataFrame and preserving the SPDF data?

I have a SpatialPointsDataFrame with some additional data. I would like to extract those points inside a polygon and at the same time, preserve SPDF object and its corresponding data. So far I've ...
15
votes
1answer
5k views

Clustering geographical data based on point location and associated point values

Given data points with longitude, latitude, and a third property value of this point. How can I cluster points into groups (geographical sub-regions) based on the property value? I searched by google ...
14
votes
2answers
8k views

Resources on using R in QGIS for R users?

I'm finding that much of the QGIS documentation is oriented toward use of the GUI. I want to be able to run R scripts in QGIS, but am having trouble finding a resource that will ground me in the ...
12
votes
1answer
683 views

Randomly altering 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, ...
11
votes
3answers
4k views

1km circles around lat-long-points in many places in world

I have hundreds of lat-long-points spread around the world, and must create circle-polygons around each of them, with radius exactly 1000 meters. I understand the points must first be projected from ...
11
votes
4answers
45k views

How to export a dataset with “SpatialPolygonsDataFrame” as a shapefile

How to export spatial datasets in R, such as tornados dataset in GISTools package, as a shapefile with the exact same spatial reference and the exact values? library(GISTools) data(tornados) ...
13
votes
2answers
22k 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 ...
8
votes
1answer
6k views

Fill the gaps using nearest neighbors

I want to fill the NA values using the average values of the nearest neighbors: r <- raster(matrix(1:16, nrow=8, ncol=8)) r[r==12] <- NA
7
votes
1answer
2k views

Split polyline by point using 'sf' package in R

I'm learning the sf package in R and would like to locate about 450 sites along the nearest reaches of a river network and to obtain the upstream and downstream distances along the reach where the ...
7
votes
1answer
6k views

Spearman correlation between two rasters in R [closed]

I have two rasters of the same area. The only difference is that they were created using two different methods. I would like to compare them and see how correlated they are pixel by pixel. Any ideas ...
7
votes
4answers
2k views

How to speed up raster to polygon conversion in R?

I've decided to process my Landsat data in R instead or ArcGIS - due to my missing knowledge of python and and because of (assumed) high computation capacities of R. I want to : import r1 raster to R,...
6
votes
1answer
2k views

How can I parse modis MOD13Q1 quality layers in R?

I'd like to parse MOD13Q1 VI quality layers in R. My original code must have been incorrect, because it gave lots of "deep ocean" flags in the middle of Brazil. After the changes suggested by Mikkel,...
5
votes
3answers
6k views

Randomly sampling points in R with minimum distance constraint?

I'm trying to randomly select a number of points within my data frame (example data below) with a constraint that the minimum distance between the selected point must be greater than a certain ...
5
votes
2answers
2k views

Seeking QGIS affine 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 ...
3
votes
3answers
4k views

Setting “R Folder” Path in QGIS Sextante

I have installed R via the R-Project website. I have QGIS installed via OSGEO4W (currently 1.9.0 Master), and have Sextante plugin installed and working with GRASS and SAGA providers. I am now trying ...
3
votes
4answers
18k views

Extract all the polygon coordinates from a SpatialPolygonsDataframe?

I want to do something relatively simply but it seems to be very difficult to do, though I am very new to using R for spatial data so apologies if I've missed something obvious. I have a list ...
8
votes
4answers
4k 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 ...
6
votes
2answers
3k views

What is the equivalent of arcpy “Con” in QGIS and/or R raster-package?

I'm looking for an equivalent of the conditional expression "Con" from arcpy in an open source spatial analysis package. I'd prefer to use QGIS or R. To provide some additional detail, I need to ...
4
votes
3answers
1k views

Download MODIS/MCD19A2 AOD product with R

I'm looking for a programmatic way to download MODIS/MCD19A2 AOD data in R. So far, I've found a pretty solid R package called MODISTools that works nicely with the MODIS/VIIRS RESTful API. However, ...
3
votes
2answers
383 views

Missing R scripts in QGIS 3 after install

After install Processing R Provider plugin (v.1.0.1) in QGIS 3.4 I only got test.rsx. I'm able to create new scritps but I can't acess scripts already installed in my OS (Linux Mint 19.1) trough R ...
3
votes
1answer
772 views

NDVI-time series with missing values

I have a Landsat-NDVI-time series from 2013 - 2017 with 23 observations per year (115 scenes in total). My goal is to get a smooth time series for a selected single pixel (maybe by using a Savitzky-...
3
votes
3answers
1k views

Reclassifying only part of raster keeping rest unchanged?

I'm trying to reclassify only a certain part of a raster...not the entire raster. Here's the problem. I have a LULC raster of the entire US. There are some issues with the raster that I want to fix,...
2
votes
2answers
1k views

Writeogr to PostgreSQL/PostGIS database with R

I'm producing some Spatialpolygondataframes with R that I would like to upload to my PostGIS Database. I've found out that the way to do this is via the writeOGR() function using the PostgreSQL driver....
2
votes
1answer
2k views

Using Loop for calculating NDVI in R?

I am using MOD09Q1 now and I would like to calculating NDVI whole year data. One year, I have 46 band 1 images and 46 band 2 images. list.files I creating list of band 1 and list of band 2. ...
0
votes
1answer
2k views

How to do spatial correlation between two sets of rasters in R?

I have two sets of rasters from 2001-2016. Obviously, these two are correlated to each other but I want to produce a map showing the degree of their correlation. The Correlation Coefficient will be ...
6
votes
1answer
776 views

Strange output from RSAGA topographic wetness index? [duplicate]

I am trying to generate a topographic wetness index raster with the RSAGA package in R. The output I am able to generate does not make sense to me, as it has a large number of NA cells and I wonder if ...
4
votes
1answer
2k 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 ...
2
votes
1answer
4k views

When aggregating points by polygons with sp::over function, how do I include attribute data from both the points and polygons? [duplicate]

Data: Zipped ea.ml1 shapefile can be found here, and the country outline can be downloaded here at the GADM site. I've been using the Ethiopia ESRI shapefile. Branch locations are here. I have a ...
0
votes
1answer
656 views

Correlation/relationship between map layers in R?

I have a point shapefile concerning asthma instances, a point shapefile concerning rainfall, and a polygon shapefile with population information i.e gender, ages etc. I would like to research if ...
27
votes
2answers
75k 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 ...
14
votes
1answer
43k views

Converting geographic coordinate system in R

I have points in geographic coordinate system and I wanted to convert them to swiss grid (CH1903+). Sample data: id lon lat 2 7.173500 45.86880 3 7.172540 45.86887 4 7.171636 45....
18
votes
2answers
25k views

Convert a spatial polygon object to data frame using R

My goal is to modify an existing shapefile by merging certain polygons. After importing the shapefile and using the UnionSpatialPolygons command, I get the polygon outline that I want. However, this ...
24
votes
1answer
19k views

Getting TopologyException: Input geom 1 is invalid which is due to self-intersection in R?

The 'TopologyException: Input geom 1 is invalid' self-intersection error which arises from invalid polygon geometries has been widely discussed. However, I haven't found a convenient solution on the ...
13
votes
2answers
7k 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)) And I ...
13
votes
3answers
28k views

Extract Raster from Raster using Polygon shapefile in R

I am new to R and using the raster package. I have a problem extracting polygons from an existing raster file. If I use extract(raster, poly_shape) function on the raster it always creates a list ...
15
votes
1answer
29k views

Converting a polygon into a raster using R

I'm trying to convert a shapefile into a raster within R. My approach is to read in the raster as follows: library(rgdal) # Loads SP package by default demo <- readOGR('F:/data/', 'shapefile') # ...
7
votes
2answers
3k views

Transforming geostationary satellite image to lon/lat

The ICARE Data and Services Center distributes the SEV_AERUS-AEROSOL-D3 product in HDF5 format (http://www.icare.univ-lille1.fr/archive/?dir=GEO/MSG+0000/SEV_AERUS-AEROSOL-D3.v1.03/). The main ...
11
votes
2answers
2k 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 ...
8
votes
3answers
10k views

Removing columns in a SpatialPolygonsDataFrame in R?

My spatial polygon data frame (SPDF) contains too many columns (variables) and I want to remove most of the columns entirely. I know how to do this with a regular data frame in R, but I am unsure ...
8
votes
1answer
5k views

Distance to nearest point for every point same SpatialPointsDataFrame in R

I have a SpatialPointsDataFrame that I'm working with in R. I want to add a new vector to the dataframe that contains, for every point, the distance to the nearest other point in the ...
7
votes
2answers
5k views

R function for Thiessen Polygons

For a point data set with temperature data I have, I want to create their Thiessen Polygons in R. So far, the only algorithm I have found is that of Carson Farmer (http://carsonfarmer.com/2009/09/...
7
votes
2answers
3k views

Clipping vs Intersecting

I was curious why clipping shapefiles was just so difficult and whether it was different to intersecting shapefiles? You will see from one my questions that I gave up trying to clip a polyline with a ...

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