5 votes
Accepted

Moran's I z-value in spdep

A "Z-score" (I wouldn't call it a Z-value) is the number of standard deviations that a statistic is away from its expected mean. The ESRI documentation https://pro.arcgis.com/en/pro-app/tool-...
Spacedman's user avatar
  • 63.9k
5 votes
Accepted

Compute Moran's I on more than one attribute

One does have to question the why here. What do you hope to achieve in evaluating multivariate autocorrelation? What hypothesis are you, in fact, testing? If this is in the context of a linear ...
Jeffrey Evans's user avatar
5 votes

Moran's I on 2D arrays/rasters?

Eventually, with the help of Serge Rey's answer and this link in the documentation, I ended up using pysal's implementation as follows: import pysal as ps w = ps.lat2W(input_img.shape[0],input_img....
GStav's user avatar
  • 309
4 votes

Defining strength of Moran's I

Yes. If I_A > I_B for two data sets A and B, then there's greater spatial autocorrelation, where spatial autocorrelation is defined by the formula for the Moran I (other measures of spatial ...
Spacedman's user avatar
  • 63.9k
4 votes
Accepted

Spatial autocorrelation has p value of 0.0000

Your variance is tiny (0.000026) compared to your Moran Index value (0.053309), so your Z score is huge (11.23) so the p-value is tiny (less than 0.00000049999 if the code is rounding). Your data are ...
Spacedman's user avatar
  • 63.9k
4 votes
Accepted

Constructing a raster with Moran's I close to -1

By defaults the Moran function uses the 8 neighbours of each cell. For your regular raster, 4 of these are the same and 4 are different to the centre cell. That's no autocorrelation. If instead you ...
Spacedman's user avatar
  • 63.9k
4 votes

Significance test for local Moran's I in R raster

The standard deviate of local Moran statistic (z-score) is derived following: z = (morans.observed - morans.expected) / sqrt(morans.variance) And the p-value for a two sided test, simply: p = ...
Jeffrey Evans's user avatar
3 votes

If a Moran's I value is close to 1, then why is it necessary to report the p-value?

It is important to additionally report the p-value because Moran's I values are often not standardized and so they are not comparable to each other. If you were trying to find the Moran's I of some ...
Randcelot's user avatar
  • 191
3 votes
Accepted

Moran's I on 2D arrays/rasters?

If the raster has r rows and c columns, then you can create a pysal W object with: w = pysal.lat2W(r,c) and use that with the Moran class. More details available at: https://pysal.org/libpysal/...
Serge Rey's user avatar
  • 131
3 votes
Accepted

Choosing value of Moran's I to say existence of spatial correlation?

I myself am still learning as much as I can about Moran's I, but I think I help figure out the answer to this question. There is a great video on coursera about spatial correlation: Based on the Z-...
mlane's user avatar
  • 160
3 votes
Accepted

Spatial weight for PySAL from a geojson file or geodataframe?

First, let us try to create a Minimal, Complete, and Verifiable example geoj = { 'type': 'FeatureCollection', 'features': { 'type': 'Feature', 'geometry': { 'type': 'Polygon', ...
keepAlive's user avatar
  • 350
3 votes

Geographically Weighted Regression with overlapping polygons

Most spatial weight matrix schemes are ad-hoc structures and don't have much bearing on the final model. So you could try various things, as long as they have the right properties. For examples: ...
Spacedman's user avatar
  • 63.9k
3 votes

Moran’s I (spatial autocorrelation) in QGIS or SAGA?

Yes, have a look at the following plug-in . In case this does not fulfill your requirements, I recommend you Crimestat IV. Their user guide provides an indepth spatial statistics analysis of data, ...
Roberto Zeeland's user avatar
2 votes

Use of Getis Ord and Moran's I

Getis-Ord G measures high/low clustering - so are there any high/low values that are close together. Moran's I checks to see if there is spatial dependence between values. So basically it measures if ...
Liam G's user avatar
  • 2,156
2 votes

Faster way to compute Moran’s Index from a very large distance matrix between geographic points

For 100,000 points your distance matrix is going to be 10,000,000,000 elements, and on typical hardware it will be size rather than time that will stop it. Any code that requires a pre-computed ...
Spacedman's user avatar
  • 63.9k
2 votes
Accepted

pygeoda - LISA for round polygon

There do not appear to be any methods to filter data in pygeoda. Therefore, you will need an additional preprocessing step to remove the polygons that you don't want to process. In QGIS, after ...
jbalk's user avatar
  • 7,505
2 votes

pygeoda - LISA for round polygon

You normally can drop NaN values from gdf and use it in pygeoda according to documentation. I encountered an issue (reported as bug). So I tried the following way. It worked for me. ... gdf = gpd....
Kadir Şahbaz's user avatar
2 votes
Accepted

Statistical significance of Moran I

You could do a monte-carlo test of I>0: First lets create a very correlated raster: > r = raster(matrix(1:(50*50),50,50)) > Moran(r) [1] 0.9694908 And now do 99 Moran's I of rasters that are ...
Spacedman's user avatar
  • 63.9k
2 votes

Computing Moran's I from a ggplot map using R

At this point: > WGScoor <- subset(map_data, YEAR == 2010) map_data is a data frame with one point per vertex and a grouping variable, like piece, that defines the polygons. You then do: &...
Spacedman's user avatar
  • 63.9k
1 vote
Accepted

Using weight component in Moran I calculation

The source of confusion may be in the two W terms in your equation--this may suggest different types of weights in the formula. It will therefore be helpful to re-express the Moran’s I equation in a ...
MannyG's user avatar
  • 653
1 vote
Accepted

interpretation of Global Moran I values using pysal

To answer the last question, I generally use GeoDA software to calculate the Moran's I (and by extension the local indicators of spatial autocorrelation [LISA]). This software does calculate a ...
Atm's user avatar
  • 1,527
1 vote

Computing Moran's I from a ggplot map using R

The data in states <- data(urbnmapr::states) are not SpatialPolygons - they're just the SpatialPoints info to build the polygons if you wanted to (which apparently ggplot does automatically for you)...
Roger-123's user avatar
  • 228
1 vote
Accepted

How to interpret spatial random permutations against the observed value of the statistic (PySAL)

The idea behind the permutation is the following: Under the null there is no spatial correlation in the data. A way of creating patterns of no spatial correlation (or complete spatial randomness to ...
Akis's user avatar
  • 36
1 vote
Accepted

Find optimal distance band after running Incremental Global Moran I with PySAL?

After a little research, I finally came up with the answer I was looking for. when using Global Moran's I index (I) with incrementally increasing distance searches (thus, changing the weight matrix at ...
Nick Pucino's user avatar
1 vote

What does first requirement for LISA statistic mean?

The key of the first requirement is related to the word significant. This implies that the observed pattern (i.e. a cluster / outlier) is not the result of a random process. To understand this, you ...
Temporalista's user avatar
1 vote
Accepted

What unit is returned by the ncf::correlog function?

The units are meters because the coordinates are meters. The x-axis goes to 1400 because the most distant possible points are (1,1000),(1000,1) and the distance between them is sqrt(2)*1000.
davemfish's user avatar
  • 299
1 vote

Calculating Moran's I for buffers of forest cover?

You are convolving what your experimental unit actually is. For information contained in "buffers" you are going to have within unit and between unit variation. You cannot collapse the within unit ...
Jeffrey Evans's user avatar
1 vote

Moran's I: Selecting the best option for conceptualizing the spatial relationship between # births & county locations

Opt for spatial weight matrix while performing autocorrelation. Let's start with K nearest neighbours: It isn't a suitable option in your case because it is used in distance references and you want ...
Maxima's user avatar
  • 1,701
1 vote

Output feature missing when using Cluster and Outlier Analysis (Anselin Local Moran's I) in ArcMap?

What Moran's I tool are you using specifically? There are two, one of which creates a separate output: Spatial Autocorrelation (Global Moran's I) Cluster and Outlier Analysis (Anselin Local Moran's ...
GISHuman's user avatar
  • 3,671

Only top scored, non community-wiki answers of a minimum length are eligible