Transcript Get Started with GIS Mapping

Get Started with GIS Mapping
Part 2 of 2, December 2009
Madhu Lakshmanan
Agenda
Data Preparation – planning, geocoding,
aggregating, data formatting ...
 Mapping aggregate data with AFF Mapper
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◦ Using data sets from the AFF website
◦ Using your own datasets in Excel
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Mapping aggregate data with Earthplot
Recap
To-Do
Resources
Homework
Data Preparation - Planning
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Having some idea of what you want to achieve
with your map
What data do you have already?
What data do you need to acquire?
If you have to convert your data, what
conversion tools do you need?
What maps can you reuse?
Data origin, metadata, processing
Discuss with other users, colleagues, peers
Data Preparation - Geocoding
Can geocode at different address levels
like state, county, zipcode, complete
address, etc.
 Multiple ways, differences in accuracy, daily
limits, one time activity
 Using BatchGeocoder.com
 Using KMLGeocoder on desktop
 Zip data with lat/long for each state
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Data Preparation - Aggregate
Useful to graph case address data at a
higher level like zipcode/county/state
 Using Excel to do sorting/subtotals
 Using the aggregate geocoded data in
tools like Earthplot
 Certain
tools need
your data to be either
Data
Preparation
- Formatting
in number format or don’t care. Knowing
which can help in troubleshooting
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Mapping your case data - points
Directly enter addresses into GE one by one.
(can import bulk if using Pro version)
 Use a tool like KMLGeocode to take your Excel
address data and convert to KML directly – no
identifying info needed other than address data.
Limit is 5000 a day.
 GE shows a map with a scatter plot of your
case data. A screenshot of this will not reveal
any specific address information to a viewer but
sharing kml will do that.
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Mapping your case data - aggregate
Useful 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
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AFF Mapper – Using datasets from
American Factfinder
Created to make maps using census boundary
files and American Fact Finder data
 Rule-based, but simple to follow
 Find a shapefile from http://www2.census.gov/cgi-bin/shapefiles/national-files
This is a one time task for a particular
geography, so make sure to extract, rename and
save the file safely.
 Extract to a folder on your computer that you
can find. There will be multiple files in the folder.
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AFF Mapper – Basic
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Go to the American Fact Finder website for datasets.
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In the left panel, choose Data Sets and a survey/census
Choose the option to create a custom table
Select a geographic type and subtypes if applicable.
Follow the prompts to select a table from the list
Filter by data elements (these will be the columns in your final
excel file)
Sometimes you can further filter the results to restrict the number
of rows
View the table before downloading.
In the toolbar above the table, you have an option to
print/download. Choose download, choose to save as an Excel file
with the descriptive field names and save. Extract the zip file to a
well named folder.
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http://factfinder.census.gov/
AFF Mapper – Basic
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Start up the AFF Mapper
Click on Input file and choose your shapefile that you had
downloaded from the TIGER site earlier.
Once that loads up, select XLS from the Join File Type and click on
Join Table. Browse to your Factfinder downloaded xls file and select
it.
It usually detects the common fields from the two files, but you
might just want to see that it has done it right.
Then click Join Tables.You should see the two tables merge
together.
Select the field that you want to be a label on your map
Click Render. Another box opens and you can choose your field to
be mapped (only after choosing the distribution type) and set the
mapping options. Set colors etc and say ok.
You return to the original screen, where you specify your output
filename and click Go. This will create a KML file for you.You can
then open it in GE.
• The variable list appears only if you choose one of the distribution
methods that allows for multiple values (Quantile, Equal Interval, Standard
Deviations, Jenks Natural Breaks)
•Choose a variable from the drop down list (pick one that is an estimate
and not one that is a “margin of error”. There are both types in the Excel
file we downloaded. i.e. for each estimate, they also give you the margin or
error in the next column).
•If you would like to normalize (divide by) another value such as the total
population in that county or the total area or something to make the playing
field level, then choose that variable in the “Normalize By” box.
•Note that these are sampled and not like census, so you may find entire
geographic areas that are empty if you choose a very restrictive variable.
AFF Mapper – for your data
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Earlier we saw how AFF Mapper can be
used to map census (publicly available)
datasets 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 format
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Your 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 – Example
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First Row
Headings
An 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:data
Second
Row
Headings 26001
ALCONA
38
26003
ALGER
90
26005
ALLEGAN
81
26007
ALPENA
18
26009
ANTRIM
26
26011
ARENAC
33
26013
BARAGA
41
Note the colon :
AFF Mapper – Example
A 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.
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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.
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AFF Mapper – Example
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Hit 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 – Example
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Choose 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 – Example
Click 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.
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AFF Mapper – Example
Earthplot
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Earthplot 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
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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.
Earthplot
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Go 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.
Earthplot
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Select 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.
Earthplot
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Click 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.
Earthplot
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Once 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.
Quick Recap
I want to
Map Community
Data
Find ready-to-use KML data
Convert from other data types
Use AFF Mapper
Map Case Data
Directly as points
on the globe/map
In aggregate form
using colors/shapes
Use a geocoder on the actual
address data & create KML
Use Earthplot or
AFF Mapper
To-Do
1.
2.
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5.
Assemble a set of tools for mapping
Begin a library of base files and data files for
mapping on your computer/server
Find sources of data for your region – many
local governmental entities and health related
organizations are good sources.
Think about what sort of maps and
visualizations work best for each purpose
Discuss maps and mapping practices with
peers.
LSNTAP GIS Resources
Several <5 min screencasts with how-tos of
specific tasks we saw in the training series
available at: http://lsntap.org/GIS_GE_Howtos
 GIS mailing list being restarted – do sign up and
discuss mapping at https://lists.mayfirst.org/cgibin/mailman/listinfo/gis
 GIS Resources section on LSNTAP.org updated
 Email your questions to Madhu or to the GIS
listserv or if you need to you can set up a G2M
with Madhu. Email [email protected]
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Homework
1.
Create maps for your area of interest
using the tools discussed today.