Practical Manual - Malareo

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First, make sure that no records are selected. Then click on Advanced search. In the Search query builder window there are 3 separate windows namely, “Fields,” “Values,” and “SQL where clause.” In order to make our selection the first thing we need to do is select those countries that are landlocked. To do this double click on Landlocked in the first window, then click on the “=” sign and then click “Sample” button below the Values window. You will see 2 options, Y and N. Double click on the ‘Y.’ You should see in the SQL where clause window the phrase: LANDLOCKED = 'Y' Now, click on the word “And,” then double click CURR_TYPE, click on the “=” sign and then select “Sample” again. This time the list of all currencies shows in the Values window. Select ‘CFA Franc.” Your full query should read: LANDLOCKED = 'Y' AND CURR_TYPE = 'CFA Franc' You can now click on the Test button to verify that you have entered a correct SQL query and a window will pop up that says 5 matching features were found. Click OK and have a look at the attributes of the 5 selected features (you may want to Show only selected features). Now run the advanced search again but instead of using And use OR. You will see that a whole lot more features have been selected. What do you notice about their attributes (taking note of currency and landlocked specifically) You can see that for advanced queries it is important to select the correct “operator” when joining 2 queries. And you should always check your results once you have run a query to see that you have results that make sense. In GIS it is easy to get results; you want to always be sure to have results that are meaningful in the context in which you wish to use them. QGIS for Malaria Page 38
<strong>Practical</strong> 6 Spatial Analysis Outline Spatial Queries Selecting by Feature Location Measurements Segment Length Distance Area Geoprocessing of Vector Data Intersect Union Clip Buffer Dissolve Geoprocessing of Raster Data Slope Analysis Aspect Analysis Rater Calculator INTRODUCTION Spatial analysis lies at the Core of the functionality of GIS. This is where most of the calculations are performed on which most decisions are made. It is through spatial analysis that patterns are discerned are relationships determined between objects based on their spatial relation to each other. This can include a single object and its location in space or multiple objects and their relation to each other. We will explore the various basis operations that can be performed using QGIS to determine different spatial relationships between objects. QGIS gives us many useful tools to carry out these calculations. QGIS for Malaria Page 39
Page 1 and 2: Introduction to Geographic Informat
Page 3 and 4: occurrences you can gain a better u
Page 5 and 6: Once in the folder, using your mous
Page 7 and 8: Map Legend You now have 2 layers lo
Page 9 and 10: Select the Identify features tool a
Page 11 and 12: 30% release it and click on Apply a
Page 13 and 14: It is important to note that althou
Page 15 and 16: Open your Identify features and exa
Page 17 and 18: Acquiring Spatial Data There are nu
Page 19 and 20: This adds the shapefile to the lege
Page 21 and 22: You will be creating a layer using
Page 23 and 24: This opens a co-ordinate reference
Page 25 and 26: Next you will create a line layer (
Page 27 and 28: Continue digitising the other roads
Page 29 and 30: If you are interested in seeing the
Page 31 and 32: PROJECT COORDINATE REFERENCE SYSTEM
Page 33 and 34: Task 1: Changing the Default CRS in
Page 35 and 36: Practical 5 Tabular Data Queries Ou
Page 37: ecords. Switching and clearing yo
Page 41 and 42: Task 1: Open a new QGIS project. A
Page 43 and 44: In order to make measurements in un
Page 45 and 46: Now to measure along the length of
Page 47 and 48: Buffer and Dissolve Buffer: Often i
Page 49 and 50: Open the Attribute Table for the Pr
Page 51 and 52: The result window shows the number
Page 53 and 54: Task 5: Slope Analysis Open a new
Page 55 and 56: Active Layers in the TOC Mathematic
Page 57 and 58: In this practical you will undertak
Page 59 and 60: 1999 (which was year 1 of the 10 ye
Page 61 and 62: updated with percentages of prevale
Page 63 and 64: Click on Set to current extent Leav
Page 65 and 66: Practical 8 Summary Practical Outli

Practical Manual - Malareo

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