Category Archives: SQLite

Sum up values of neighbouring polygons – a GRASS GIS approach

How to sum up values of neighbouring polygons in QGIS? This question was asked on gis.stackexchange, with two interesting answers. One answer explains how to use Spatialite and SQL to achieve this. The other answer, explained in more detail here, presents … Continue reading

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Spatialite 4.0 is out

The release of Spatialite 4.0 was just announced on the Spatialite user group. You can download it from the Spatialite website. And while you are on the website, check out the page about switching to 4.0. Version 4.0 introduces several … Continue reading

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Reprojecting your layer in Spatialite

I have a vector layer ‘nursery data’ in a Spatialite database. The coordinate reference system of the layer is WGS84 geodetic (EPSG 4326). What if I need to reproject the layer in WGS84/UTM37N (EPSG 32637)?

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Find and select duplicate values in your vector attribute table

Suppose you have a vector layer in your GRASS GIS database and you want to find all duplicate values in one of the columns of the attribute table of that layer? If you are using SQLite or PostgreSQL as the … Continue reading

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Extract X and Y coordinates from a spatial table in Spatialite

A quick note on adding two columns with X and Y values in a vector layer in spatialite. Spatialite stores the information about the geometry in binary format in the ‘Geometry’ field. You can use the Spatialite function AsText() to … Continue reading

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Split strings in SQLite

I am just back from vegetation survey in Kenya and Uganda. Before starting with the analysis, I will have to go through the more boring data entry and organization. I will use a Spatialite database to store all the data … Continue reading

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Concatenate in SQLite

I wrote before on using concatenate in OpenOffice / LibreOffice and how this alternatively can be done in R using the paste function. You can do the same in SQLite using a query too.

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SQLiteMap

Looks interesting, a R package that provides bindings to Spatialite functionalities. Through this bindings one can carry out the spatial functions available in Spatialite from within R using simple SQL statements.

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Select random sample from SQLite table

I came across this post by underdark about how to select a random sample from a table in PostgreSQL. You can achieve the same (selecting 1000 random features from a table) in SQLite using something like below:

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New spatialite plugin for QGIS

For some time now it is possible to load SpatiaLite data layers in QGIS. It is read only though, any changes will need to be saved as shapefile. There is a Spatialite manager plugin, which offers an interface to the … Continue reading

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