How to Analyse Your Data Using The Spatial Analysis Tool
Spatial analysis is a type
of geographical analysis used to explain patterns of human
behaviour and its spatial expression in terms of mathematics
and geometry, i.e. locational analysis.
In this guide we will show you how to analyse your data using the Azimap
Spatial Analysis tool. We’ll use
a working example, importing two shape (zipped) files of nuclear reactors, and
performing some spatial analysis on them.
Time to complete: 20 mins.
1. Getting started
1.1 Download files
1.2 Create a new map
1.3 Import data and add to map
of the spatial analysis wizard
of basic functions
of advanced functions
and advanced functions in use
Within, Contains, Touches
1. Getting started
1.1. Download files
Nuclear Reactors 2011 
1.2. Click on MAPS section and CREATE MAP
Press the CREATE MAP button.
When you enter the map creation wizard, name your new
map and click NEXT.
1.3. Import data and add to map
The next step in the map creation wizard is 'Add Datasets to Map'. You have a few options here: You can create a new layer to add to your map, you can choose to add one or many of your existing layers to your map, or you can create an empty map with no layers.
In this case however, we'll choose
the CREATE LAYER button (this is also accessible on the map using the gears
button on the layer tree view). You'll be prompted with the below
pop-up. Select YES, GO.
This will automatically bring you to
the first step of the CREATE DATASETS wizard.
Choose CREATE OR CONNECT NEW DATASETS
In the next step of the wizard,
you'll choose the AZIMAP option below
Drag and drop earlier downloaded zip files (we
support zipped files or non-zipped).
After upload, the projection is automatically
chosen and a suggested name is added for each new layer based on the file name
(change this to any name you would like).
Click SAVE to import the layer (this may take a few
seconds - the larger the datasets the longer it takes).
After successful import, the map will load with the
default styling (little red squares) and grey polygons.
2. Spatial analysis
Click on the ANALYSIS button.
An Analysis sub-menu will appear where you can pick SPATIAL ANALYSIS.
· The spatial analysis wizard will begin.
2.1. Functions of the spatial analysis wizard
2.1.1. Explanation of basic functions
This is a powerful wizard with multiple functions.
- Select layer - Choose the layer from which to get results
- Spatial function - 6 built-in spatial functions, as follows:
1. Intersects Returns a result if two
geometries "spatially intersect in 2D" - (share any portion of
2. Buffer Returns results within a
given distance from the input geometry.
3. Overlaps Returns a result if the
geometries share space, are of the same dimension, but are not completely
contained by each other.
4. Within Returns a result if the
geometry A is completely inside geometry B.
5. Contains Returns a result if and only
if no points of B lie in the exterior of A, and at least one point of the
interior of B lies in the interior of A.
6. Touches Returns a result if the
geometries have at least one point in common, but their interiors do not
Azimap utilises Postgis for its spatial analysis (Postgis Reference). Other functions can be utilised if entered directly into the query
window (further details below).
2.1.2. Explanation of advanced functions
Update radius - Distance for buffer (enabled on buffer analysis) options for
m, km and miles.
Geometry source –
Select area type (enabled
on MULTIPLE FEATURE select)
Secondary layer (enabled
on COMPARE LAYERS select) - When comparing layers,
choose the secondary layer to compare.
2.2. Basic and advanced functions in use
Let’s use the wizard to select all the nuclear stations in France.
France to select the country polygon (it should highlight)
LAYER (NuclearReactors2011) in SELECT LAYER drop down
TOOLS in SPATIAL FUNCTION choice
Select the SELECT
A FEATURE tool
SCRIPT - this will generate the required SQL output all the nuclear power
stations that intersect with the France country polygon
FILTER to see your results
You can view the results in tabular format by clicking the VIEW DATA
VIEW DATA shows the filtered 46 power stations in France.
The SAVE RESULT AS A NEW LAYER button does as it says giving you the
option to add it to the map or just into your data catalog.
Added to the map it should look like below with the new 'FrancePower'
2.2.2. Overlaps, Within, Contains, Touches
To perform any of the above spatial analysis just follow the process in step
2.2.1 but choose your applicable option from the SPATIAL FUNCTION section.
2.2.3. Buffer select
Creating selection buffers is slightly different - you must select the
radius of your buffer after choosing the BUFFER SELECT function.
Process the query as per step 2.2.1 only this time set a buffer radius
(will be enabled if BUFFER SELECT is chosen).
In this query we’ve selected a random power station in France and set a
1000 Km buffer zone.
The outcome is, the only the resulting answers being shown on the map.
The wizard creates query SQL for you, however if you know SQL syntax you
can write your own advanced select queries by either editing the output of the
wizard or choosing the ADVANCED RADIO button (above the RESET button).
NOTE: Strings should be surrounded by single quotes. Double quotes are used by us to signify table
names and column names.
The SQL query box can now be typed into - to search for reactors of type
Where type = 'Pressurised
or for reactors that are gas cooled.
We can combine wizard generated queries with our own amendments.
Generate the intersect query from set 5.
This results in the below filtered dataset.
Let’s amend the query by adding year of construction between 1970 and
1979 inclusive (we will utilise the SQL BETWEEN command which is inclusive).
BETWEEN 1970 AND 1979 AND
We have added a new line into the wizard generated query creating a new
1st WHERE clause and placing the spatial portion after an AND clause.
This results in the more filtered dataset showing rectors built in the
Let’s check the 1980's.
BETWEEN 1980 AND 1989 AND
Lots of building going on in France in the 1970s and 1980s!
Thanks for reading the guide and we hope you get some great analysis
from your data.
If you haven't signed up yet go to the Azimap website and click REGISTER.
file downloaded from Sharegeo Open - NuclearReactors2011 "This data is made available under the Public Domain
Dedication and License v1.0 whose full text can be found at opendatacommons.org"
sourced from thematicmapping.org
The original shapefile (world_borders.zip, 3.2 MB) was downloaded from
the Mapping Hacks website
The dataset is available under a Creative
Commons Attribution-Share Alike License.