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Geographic Information Systems

Questions tagged [sample]

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15 questions
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0
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0answers
31 views

Stratified random sampling in R? [closed]

I have a data table like > head(sdmdata) pb aspect covertype disnr disrespt disroad diswater elevation kernelrespt slope 1 1 167.53506 6 0 607.4537 14624.81 57834.41 ...
3
votes
0answers
32 views

Sampling list of rasters in ArcPy?

I've been trying several times to sample (Sample tool from Spatial Analysis ArcGis 10.5.1) a list of rasters to a location sample (also in raster format .tif). Here's the code I've been using, and ...
0
votes
0answers
29 views

Randomly Sample Raster Pixels With a Minimum Distance in QGIS

Is there a way I can sample random raster pixels from a satellite image with QGIS or QGIS plugin? I also need each randomly-chosen pixel to have a pre-defined minimum distance from the other raster ...
0
votes
1answer
89 views

How can ee.Image.stratifiedSample() be used in Google Earth Engine to select training samples for a binary classifier?

This is a follow-on question to How can one create a binary image from a FeatureCollection in Google Earth Engine? The corresponding minimal example can be found here: https://code.earthengine.google....
1
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0answers
49 views

R raster - take stratified sample

This question was posted in stackexchange, where there were no views/comments/answers. I have a raster file and would like to take a stratified sample. library(raster) f = system.file("...
1
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0answers
16 views

Kriging with a non-uniform (not space filling with concentrated data in certain regions) sampling design?

I am using Kriging for optimization where local searches are often carried out. However, because of these local searches my sample design becomes poor and my Kriging prediction as well as variance ...
1
vote
0answers
510 views

Converting table asset data type from 'Long' to 'String'

I am attempting to generate 50 random points per land use class through Google Earth Engine. I have performed this operation before on an earlier instance, where the inputs were the following (1) ...
1
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0answers
168 views

Small sample size for geographically weighted regression; limitations

I am studying West Nile Virus risk factors in a specific county using mosquito surveillance data over a ten year study period. The highest resolution of the mosquito data that could be obtained was at ...
0
votes
1answer
412 views

Distance based random point selection in r?

To avoid clustering in subsequent analysis I try to randomly select points of a SpatialPointsDataFram with a given distance between the points. The remaining part should be devided for test analysis. ...
0
votes
3answers
393 views

Random sampling of many millions of Points or raster cells with ArcGIS Desktop?

I need to test the mean of two very big point shapes. One point shape has around 34.000.000 points and the other around 1.000.000. I have to do a random sample in ArcGIS 10.3.1. Unfortunately, I ...
1
vote
0answers
89 views

Random Stratified Sample in QGIS and Scale

I need to sample 7 raster layers all 30 m resolution (as some of the remotely sensed products I'm using are Landsat). I have all of my layers ready to go, but I am not sure how I can conduct a ...
1
vote
1answer
73 views

Sample values from a grid by points in RQGIS

I need to sample values from a grid by points. In RSGA, there is a function called "pick.from.saga.grid" to sample raster data set using points. Is there something similar in RQGIS?
6
votes
1answer
231 views

Why does the ArcGIS Sample tool skip rows and points?

I'm using ArcGIS 10.4 and want to export XYZ values of a raster (type: GRID) to a text file. I'm following the procedure recommended by ESRI support. However, it seems that the Sample Tool in spatial ...
2
votes
1answer
303 views

Generate sample (Gaussian distribution) and store simulations in raster stack in R

I have a raster stack, one of the raster layers is the mean prediction of a property for that pixel, the second layer is the variance of the prediction. I would like to write a function for ...
1
vote
1answer
102 views

Sample point elevation from a given contour

I need to sample the elevation at number of predefined location given in CSV format (but could convert to shapefile if needed). My input data is a shapefile of contour lines. Is it possible to sample ...