Get Started with GIS Mapping Part 3 of 3 Madhu Lakshmanan.

Get Started with GIS Mapping

Part 3 of 3

Madhu Lakshmanan

AgendaWeek 2 – Redux

◦EarthplotAFF Mapper – using your own

dataRecapTo-DoResources

Mapping your case data - aggregateUseful to denote differences in

numbers at an aggregate level such as zip code on top of other layers

Need to have your data prepped as aggregates and geocoded beforehand.

Earthplot is a simple tool that creates such graphs for GE. (GE-Graph is one other more complex tool.)

AFF Mapper also requires your data to be aggregated but does not require geocoding. It creates the shaded graduated maps and not graphs

EarthplotEarthplot requires data such as: the column that

has been aggregated upon (e.g. zipcode), the actual aggregated values (e.g. counts), its latitude and longitude (the latitude and longitude of an area is usually created using its centroid) and any other data you might want to show in the description.

Zip Cases Latitude Longitude

87002 1 34.5756 -106.588

87004 4 35.4078 -106.82

87005 1 35.1385 -108.242

87006 1 34.4828 -106.805

87016 1 34.748 -106.158

87017 3 36.2277 -106.819

Earthplot In Earthplot, you will see 2 tabs, a Data tab and an Options

Tab. Copy your Excel aggregate geocoded data and in Earthplot, in

the Data tab, go to Edit->Paste and you will see your data appear in the same way that it appeared in Excel.

EarthplotGo to the Options tab and set various options. In

this example, we use a Graduated sizes type of map with one variable.

Set the columns to the correct items, i.e. longitude in column D, latitude in Column C etc. Make sure you have them right by looking at your data tab again. The variable column is the one in which the Count is stored.

EarthplotSelect the shape to be ‘circle’ for this example

and Set the minimum and maximum sizes of your circle to be 0.05 and 0.3 to start with. You can keep tweaking these sizes and perhaps even the Ignore values box as you see your graph being created. Also set the color for your circles.

EarthplotClick on Plot to GE

icon in the toolbar and you should see your circles appear on the map. Tweaking the sizes, colors, and perhaps setting a number in the ignore box will help create the graph you want.

EarthplotOnce you have the graph you

like, go to Earthplot and in the menu, choose Export to KML and give it a name and save. This way you will have a saved copy of your KML file.

AFF Mapper – for your dataIn the earlier training we saw

how AFF Mapper can be used to map census data onto base shapes, but we can also use it to map our own data as long as it is put in a form that the program understands.

AFF Mapper – Data formatYour data needs to be in aggregate form, in

Excel, aggregated to the level that you want to categorize on. e.g. if you want to see county-wise color graduated map, then your data should be aggregated to the county level

The columns that contain this level should be in both the base shapefile and your data file. e.g. your data file should contain the county code/name if that was your aggregation level.

The top row of your file can be the column headings. In the second row, you can have descriptive headings for your data. It is very IMPORTANT to use a colon ‘:’ in the 2nd row heading for those columns that are to be treated as NUMERIC, otherwise you will not be able to map those columns. E.g. you can call a column Case : Total

AFF Mapper – ExampleAn Excel file with Michigan County-

wise data aggregates is chosen. The 2nd row headings are created making sure that the numeric data field/s have colons in the 2nd row headings.

CCode CName Data

countycode countyname Cases:data26001 ALCONA 38

26003 ALGER 90

26005 ALLEGAN 81

26007 ALPENA 18

26009 ANTRIM 26

26011 ARENAC 33

26013 BARAGA 41

Note the colon :

First Row Headings

Second Row Headings

AFF Mapper – ExampleA Michigan County level shapefile from

the Census TIGER/Line was downloaded to serve as the base layer for the data.

Start AFF Mapper and use the county map of Michigan as the Input shape.

Then, under ‘Select Join FileType’, select XLS file and in the Join File box, browse for your previously created Excel file with the county aggregated data.

AFF Mapper – Example Once that is loaded, set the Shape Join Field and the Table Join Field to

be the same data, i.e. the level to which the data is aggregated, in this case County.

The names of the columns might be different, but all that matters is that they contain the same type of data.

In this example, we might set the Shape Join Field to CNTY|DFP and the Table Join Field (which is our data) to CCODE.

Alternatively, we could also use Name and CNAME but a code is usually more efficient than a name because of spellings etc.

AFF Mapper – ExampleHit Join tables and you should see the

tables merge into one. Scroll to the right to see if your data is reflected in the table.

AFF Mapper – ExampleChoose the County Name to be the Label Field

and hit Render.You will be able to choose a classification

scheme – note that I have chosen Jenks Natural Breaks in this example.

Then pick the variable to be mapped – data, select the number of classes and colors and click OK

AFF Mapper – ExampleClick on Output KML and enter a name

for the output file. Then Click Go and wait for the “Finished” message.

You can then open Google Earth and open this file and see the result.

AFF Mapper – Example

Quick Recap

I want to

Map CommunityData

Map Case Data

Directly as points on the globe/map

In aggregate formusing colors/shapes

Use a geocoder on the actual address data & create KML

Use Earthplot or AFF Mapper

Find ready-to-use KML dataConvert from other data types

Use AFF Mapper

To-Do1. Assemble a set of tools for mapping2. Begin a library of base files and data files

for mapping on your computer/server3. Find sources of data for your region –

many local governmental entities and health related organizations are good sources.

4. Think about what sort of maps and visualizations work best for each purpose

5. Discuss maps and mapping practices with peers.

LSNTAP GIS Resources‘Lunch and Map’ open house same time

next week. Bring homework, bring questions, answers, food…

Roundtables: Aug 13, Oct 8Next Training series – Sep 11,18,25GIS mailing list resurrected – do sign up

and participate https://lists.mayfirst.org/cgi-bin/mailman/listinfo/gis

GIS Resources section on LSNTAP.org updated

Set up a meeting with Madhu if you need support. Email [email protected]