Collecting and analyzing numerical data or making numerical summaries of data.

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2
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1answer
247 views

How to create a x-y scatterplot from attributes in QGIS 2.0?

There are a few old packages that allow the creation of x-y scatter plots from attributes in vector data (Scattergram for 1.7) http://plugins.qgis.org/plugins/scattergrammidentify/ (SPQR for very ...
1
vote
1answer
158 views

What do “count”, “mean”, and “sum” in QgsZonalStatistics mean?

I am working with Qgis and making some analytics of lightdata. I've used these commands: rasterfile = qgis.utils.iface.mapCanvas().currentLayer().source() vectorlayer = ...
0
votes
0answers
51 views

Why does it take so long to run zonal statistics?

QGIS 2.0 Windows 7 I have pulled agricultural data from NASS CDL in tiff format. I want to track where a certain crop has grown over the years. My intention was to use a county shapefile overlaid ...
1
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0answers
34 views

Cell Statistics in QGIS

Cell Statistics in ArcGIS will calculate the mean (or statistic of choice) among multiple rasters on a cell-by-call basis. Can QGIS do this? If so, how?
2
votes
3answers
199 views

Select layer by attribute: return top 3 records

I have a feature class in a file geodatabase using ArcGIS 10.1. I want to create a model that selects the three features with the highest values in one field (Average Price). Basically I want my ...
2
votes
0answers
121 views

Bivariate Mapping (running a single variable regression and mapping r-squared value)

I am hoping to produce a bivariate map displaying the correlation between two variables (specifically percent SNAP participation by county against several social variables). I would like to produce ...
1
vote
0answers
68 views

Statistically compare two density maps?

I (will) have a modelled distribution and an observed distribution of animals. If I were to interpolate these position datasets to reflect some density distribution (perhaps using a kriging ...
0
votes
0answers
118 views

Calculate ANOVA using GIS

It's possible to calculate a statistic like ANOVA using GIS. I'm using ArcGis, but there's any GIS software to calculate it? Thanks,
1
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0answers
47 views

How to export raster into ascii without losing the statistics?

I had a problem in Mike Urban with a difference between a DEM (Digital Elevation Model) and a 2D overflood model and the support group requested me to remove the difference because the problems were ...
2
votes
0answers
59 views

Habitat Modeling and OLS Regression [closed]

I’m performing some habitat modeling for a certain species using resource selection functions to determine optimal variables for including as model parameters. I am using OLS within ArcGIS for the ...
0
votes
0answers
51 views

Zonal statistics returns wrong values in QGIS

I used zonal statistics for a simple task: to transmit raster pixel values to vectormap which contains squares as big as the pixel size is. The problem is that the values of the outcome are not ...
2
votes
1answer
185 views

GIS Analysis - best way to combine and display demographic data?

I am currently undertaking a demographic research project for my employer. We have the data on income, age, sex, language, transport etc and I have mapped most of it and created some thematics of said ...
0
votes
1answer
65 views

Creating quintiles in QGIS when the number of observations per row is variable

I have a list of 100s of schools (1 per row), and a variable column with the total students in each school. The number of total students in each school varies widely. I want to split the list of ...
1
vote
2answers
80 views

How do simple statistics based on polygons?

Hi I have a shapefile from a city. I divided this shapefile into polygons (squares, majority). I would like to perform simple statistics in each square in a easy way, because it is almost impossible ...
0
votes
1answer
53 views

How to use the local macro to do ZonalStatisticsAsTable in batch

I have a series of files named as 'rawfile200101', 'rawfiles200102',...,'rawfile201104'. I want to do ZonalStatisticsAsTable for each of them with names corresponding to the time of the raw files, ...
0
votes
1answer
61 views

How to calculate statistics for several subcatchments (polygons) in the same time? [duplicate]

I have a shapefile of groundwater management zone which is composed of 40 subcatchments (40 polygons). I'd like to calculate the max., min. and mean elevation for each subcatchment. Would you please ...
0
votes
1answer
61 views

How do I get basic statistics on a field in a joined table?

I have a shapefile to which I've joined a table, matching with an ID field. All the fields of the table show up correctly when I open the shapefile's attribute table. But when I go into ...
1
vote
1answer
26 views

How to Compress/Stack Landscape features to examine spatial distribution and fragmentation?

I was wondering if anyone could help me figure out how to compress landscape information from multiple rasters (or polygons) into a single output. Basically, I want to explore how landscape ...
2
votes
2answers
1k views

Iterate through multiple Raster files and compute statistics using Zonal Statistics

I have a large number of raster images. What I'd like to do is to compute statistics on different sections of these raster files using a polygon. I think everyone is suggesting Zonal statistics. ...
1
vote
0answers
89 views

Mann-Whitney U test for rasters

I'm doing a Mann-Whitney U test to compare two very large samples (sample size 1 = 13250; samlple size 2 = 38871) originating from a shapefile with 52121 features. I know t-tests are not recommended ...
1
vote
1answer
69 views

resampled thematic map accuracy

I've generated a map of ecoregions based on some environmental data using a semi-supervised classification where I combined a statistical clustering with random forests to generate my map. I created ...
4
votes
1answer
211 views

How to create Series of Rasters that displays Standard Deviation from Mean?

Cell statistics question for you. I have 100 rasters of raw rainfall data in which the pixels each represent rainfall for that particular pixel on the landscape for a single year during the 100 year ...
3
votes
0answers
31 views

Finding closest anticorrelated polygon or automate what is learned in semivariogram?

I am trying to do spatial autocorrelation of sorts based on a layer of polygons of mean rainfall data. I want to see how rainfall deviates from a certain point on the landscape. Essentially, I want to ...
2
votes
1answer
878 views

How to call processing toolbox in Qgis' python console

I have been trying to use processing toolbox via python console in Qgis 2.0.1. I am able to write the following comamnds: I am particularly interested to run 'r.statistics' from GRASS module. ...
3
votes
1answer
410 views

PCA on correlation matrix in ArcGIS

I am trying to run a PCA on a set of normalized raster bands within ArcGIS. I would like to calculate the PCA on the correlation, not the covariance, matrix of the PCA, but Arc as far as I can tell ...
0
votes
1answer
229 views

How to perform GRASS v.rast.stats via QGIS

I have been using qgis for the last few months. I got interested in using GRASS tools through QGIS. I wanted to compute zonal statistics for a raster surface for a given polygon layer. I loaded the ...
3
votes
1answer
266 views

How to sum up all field values in QGIS modeler

I am building a model to generate two zones around a point, a 250m-buffer, and a ring of 250 to 1000m, where i recalculate values from an other layer according to the intersections share. The purpose ...
5
votes
2answers
159 views

Different models, different contours: are they comparable?

I will get contour lines of electromagnetic field strength around power lines. The contours will be calculated by different agencies using different models. We need to check whether the resulting ...
3
votes
3answers
974 views

How to count occurrences of one field grouped by values of another?

Is there a way of calculating the number of unique text strings in a field in ArcGIS 10.1? I have a number of repeated strings in this field, but would like to calculate the number of unique strings ...
1
vote
1answer
797 views

What is the difference between nominal, categorical, ordinal, interval and ratio measurements?

Given the following examples, which are examples of nominal, categorical, ordinal, interval or ratio measurements? bushels of wheat per county vegetation type average maximum daily temperature ...
1
vote
1answer
459 views

identify percentage of raster cells within a polygon

As per the title I want to determine the population inside multiple polygons according to different land use zoning (High Residential, Low Residential, National Parks etc) that's in raster format. ...
1
vote
1answer
131 views

Retrieving the proportion of specific pixel class from CHM rasters

CHM = canopy height model I am very new to R (specially for GIS purposes) and I am struggling a bit in getting the following pixel statistics: Proportion of zero value pixels = [nº of zero value ...
0
votes
1answer
494 views

How to calculate median value of polygon from points in ArcGIS?

I have a point layer coming from LIDAR data containing x,y,z and intensity values. On the other hand I have a layer containing several polygons. All the points are inside the polygons. I need to ...
5
votes
1answer
380 views

QGis Zonal Statistics Plugin NoData included in Calculations

I have been trying to use the QGIS zonal statistics plugin. My raster has a nodata value of -99999 and all other values are positive. After computing the mean zonal statistics there are a number of ...
3
votes
1answer
251 views

Sensitivity analysis for coarse scale GIS epidemiological model?

I am working on an epidemiological model with disease incidence rate as dependent variable and environmental factors as independent variable. Disease data is available at county scale whereas ...
1
vote
1answer
155 views

Sum of point attributes inside hexagons using QgiS UI

I'm very new to Qgis so I would very much appreciate any help you can give me. I have a point shapefile that corresponds to locations of animals captured. I've joined a table to this shapefile with ...
2
votes
2answers
274 views

Looking for ArcPy tool for calculating statistics on field with summary field AND boolean fields

What I'm searching for is a tool that will sum a field by a secondary unique field AND booleans... Let's say I have 12 table each with 4mil records and the following fields: Donation_Amount ($ ...
1
vote
3answers
55 views

Europe sub-national urban rates

Urban rate (the % of population living in urban areas) is a rather common demographic indicator, at nation-level resolution. I'm trying to locate sub-national urban rate data (NUTS level 2 to be ...
3
votes
0answers
123 views

Why are my raster mean and standard deviation -1?

I have a set of about 25 rasters whose descriptive statistics I have been examining. The data in the rasters were calculated in Python and the rasters were created using Python-GDAL. In all but one ...
0
votes
1answer
121 views

QGIS create point data attribute as the name of the polygon it falls in

I'm working in QGIS with a point data set overlaying a farm with 140 fields. While I can analyse the points from each field individually, I would rather use an awk script to calculate statistics I ...
8
votes
2answers
206 views

spatial and spatiotemporal analyses

I have a dataset that consists of 247 mosquito traps placed in fixed positions and sampled weekly for 23 weeks. I also have dengue disease incidence data (indexed to home address) during the same time ...
1
vote
0answers
102 views

Reshape Matrix and perform Zonal Statistics in Matlab

I have 2 grids: 1) n by m - at 100m 2) n*10 by m *10 - at 10m. These grids cover the same area. I have to perform zonal statistics at scale of grid no.2. Cell value of grid no.1 is cumulative for ...
4
votes
0answers
263 views

How to analyse correlations between variables and points? [closed]

I have just lost the past 8 hours on this, and literally getting nowhere - hoping someone can help before I go mad! I am trying to determine the correlation between sinkholes and a number of ...
2
votes
0answers
72 views

How to join two fields after calculating?

I have been working with two layers and I am trying to join them and turn them into a raster data. The first layer is a watershed layer which I have assigned each shed a location from the center point ...
1
vote
0answers
411 views

QGis Grid statistics for polygons error - Module caused access violation!

I'm trying to calculate statistics for a raster layer using an overlaying polygon layer, I'm using SAGA "Grid Statistics for polygons" function, but it returns an error, sadly.. So in the sextante log ...
3
votes
2answers
2k views

Is there a zonal statistics tool to calculate median and mode raster values for each polygon?

I'd like to calculate zonal statistics for a raster where the zones are defined by polygons in a vector layer within QGIS. Specifically I'm interested in calculating the median and mode raster values ...
1
vote
2answers
122 views

r.regression.multi - ERROR: Not enough valid cells available

I am running a few analyses with r.regression.multi in Grass 7. For a few rasters that I try to correlate, the following error comes up, however: "ERROR: Not enough valid cells available". I cannot ...
0
votes
1answer
496 views

min and max values are not correctly calculated for DEM

I'm working with DEM in QGIS and need to know the min and max values of my data. In the Properties window, under the Metadata tab, the statistics section shows such values. However, I usually find ...
1
vote
1answer
80 views

Grass7 - r.regression.multi and new raster

I am on the learning curve with Grass7. I managed to make r.regression.multi work, but there is one thing that would be of high interest for me: it is possible to create a new raster showing the ...
0
votes
1answer
80 views

Grass 7 - where is r.regression.multi hiding?

I compiled Grass 7 on Ubuntu and all works fine - except, I cannot find r.regression.multi. I installed it, yet it is nowhere to be found in the drop-down menus; r.regression.line is there and works, ...