QGIS/C4/Nearest-Neighbour-Analysis/English-timed

Time	Narration
00:01	Welcome to this tutorial on Nearest Neighbour Analysis in QGIS.
00:07	In this tutorial, we will learn about
00:11	Nearest Neighbour Analysis by Distance matrix method.
00:16	Statistics using Nearest Neighbour Analysis tool.
00:21	Here I am using, Ubuntu Linux OS version. 16.04 QGIS version 2.18
00:32	To follow this tutorial learner must be familiar with QGIS interface.
00:39	For pre-requisite QGIS tutorials, please use this link.
00:45	The files required to practise this tutorial are available in the Code files link.
00:52	Please download and extract the contents of the folder.
00:57	Here I have the folder with the required file to practise this tutorial.
01:04	Double-click to open the folder. Here you will find, Urban areas.shp and Volcanoes.shp.
01:15	Volcanoes.shp layer shows active volcanoes in the world.
01:21	Urban areas.shp shows populated urban areas of the world.
01:28	Open the two shape files in QGIS, select both the files.
01:35	Right-click and select Open with QGIS Desktop option from the context menu.
01:42	QGIS interface opens with two layers loaded in the layers panel.
01:49	Right-click on the volcanoes layer and select zoom to layer option.
01:55	On the canvas you will see a map with point features.
02:01	Let us label these point features.
02:05	Right-click on Volcanoes layer, from the sub menu click on Properties.
02:12	Layer Properties dialog-box opens.
02:16	Select Labels from the left panel.
02:20	Select Show labels for this layer option from the drop down.
02:25	In the Label with drop down select Name.
02:29	Here you will find various options to modify the label style.
02:34	Choose the required style and click on OK button.
02:39	On the canvas, points with the names is displayed.
02:44	Similarly let us label Urban areas.
02:51	On the canvas point features are labeled with their cities.
02:57	QGIS has tools to analyze spatial relationships between features.
03:04	One such tool is Nearest Neighbour Analysis.
03:08	Nearest Neighbour Analysis is used for the following analysis.
03:13	Finding distance between two Point features.
03:17	Finding features which are closest to a given feature.
03:23	First, we will create distance matrix for calculating the distances.
03:29	Let us open the attribute table for the Volcanoes layer.
03:34	Right-click on Volcanoes layer.
03:37	Select Open Attribute Table.
03:40	In the attribute table there are multiple columns.
03:45	Various attributes for the point features are listed here.
03:50	Names of the volcanoes and their locations are also listed here.
03:56	Close the attribute table.
03:59	Open the attribute table for the Urban areas layer.
04:04	Notice the various columns in the table.
04:08	You will find names of the cities, countries and other information in this table.
04:15	Close the attribute table.
04:18	Let us calculate the distance between the active volcanoes and nearest cities.
04:24	Click on Vector menu.
04:27	Select Analysis Tools.
04:30	Select Distance Matrix option from the sub-menu.
04:34	Distance Matrix dialog-box opens.
04:38	Please read the description about Distance matrix on the right-panel.
04:44	By default Parameters tab opens on the screen.
04:49	Select the Parameters as shown here.
04:53	Select Volcanoes as an Input Point Layer.
04:58	Select NAME as Input unique ID field
05:03	Select Urban Areas as Target Point Layer.
05:08	Select City as Target unique ID field.
05:13	Keep Output matrix type as Linear.
05:17	Let us find the distance from the volcano to two nearest cities.
05:23	Hence, select 2 in Use only the nearest target Points field.
05:30	Click on the 3 dots button next to Distance Matrix field.
05:35	From the drop-down menu, select Save to file. option.
05:40	In the dialog-box, give an appropriate name and location.
05:44	Choose Files of type, as CSV .
05:49	In the Encoding field choose System. Click on Save button.
05:56	In the Distance matrix dialog-box check the check-box for the following. Open output file after running algorithm.
06:06	Click on the Run button at the bottom-right corner of the dialog box.
06:12	The process will take few seconds.
06:15	A new csv layer named as Distance matrix is added in the Layers panel.
06:22	Open the attribute table for Distance matrix layer.
06:27	In the attribute table there are three columns. The last column is the distance between the volcano and nearest city.
06:38	Please note, here the distance is in meters.
06:43	This is because the layers are projected in WGS 84 UTM Zone 46N system.
06:52	Depending on the CRS, the distance can also be in layer units or in degrees.
07:00	Also observe that for each volcano, two nearest cities are listed.
07:07	Let us get some statistical analysis for the layers using Nearest neighbour tool.
07:14	We will run a nearest neighbour analysis to analyze the distribution of features.
07:21	The results will establish, the distribution as clustered, dispersed or random.
07:29	Close the attribute table.
07:32	Click on Vector menu.
07:35	Scroll down and click on the Analysis Tools.
07:40	From the sub-menu, select the Nearest Neighbour analysis.
07:46	Nearest Neighbour Analysis dialog-box opens.
07:50	Read the information given about Nearest neighbour analysis on the right-panel.
07:57	Select Volcanoes layer in the Points drop-down.
08:02	Click on Run button at the bottom-right corner.
08:06	Results window opens.
08:09	Some statistical parameters for the volcanoes layer are listed here.
08:15	Observed mean distance
08:17	Expected mean distance
08:20	Nearest neighbour index
08:23	Number of point features and Z-Score.
08:29	The Nearest Neighbour Index is expressed as the ratio of the Observed Mean Distance to the Expected Mean Distance.
08:39	If the index value is less than 1, the pattern exhibits clustering.
08:45	If the index value is greater than 1, the trend is towards dispersion.
08:52	Here the Nearest Neighbor Index value of 0.2 indicates clustering. Which means, the volcanoes are located close to each other.
09:04	Similarly a negative Z-Score also indicates clustering of point features.
09:10	Close the Results window.
09:13	Save the project using Project menu.
09:17	Let us summarize.
09:19	In this tutorial we have learnt about,
09:22	Nearest Neighbour Analysis by Distance Matrix method. Statistics using Nearest Neighbour Analysis tool.
09:32	As an assignment, Create Distance Matrix for nearest 5 volcanoes to urban areas. Hint: Use Urban Areas as Input and K as 5.
09:46	Your completed assignment should look as shown here.
09:51	The video at the following link summarizes the Spoken Tutorial project. Please download and watch it.
09:59	The Spoken Tutorial project team conducts workshops and gives certificates. For more details please write to us.
10:09	Please post your timed queries in this forum.
10:13	The Spoken Tutorial Project is funded by, MHRD Government of India.
10:20	This tutorial is contributed by Ambadas Maske from College of Engineering Pune, Snehalatha Kaliappan and Himanshi Karwanje from IIT Bombay. Thank you for joining.

Contributors and Content Editors

PoojaMoolya