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Basic
GIS Tools - Exercise 3
Scenario:
You have been asked to change the map to show which ozone monitors are
active, by making them have different symbols.
Step 1
Determine field to use
Activate the 'State
Map' data
frame. Open the
attribute table
of the ozone monitors layer in the active
data frame. Scroll through the table and determine which
field indicates the active/inactive status of the site (look for A or
I).
1.) What field indicates the site active/inactive
status?_________________________
Step 2 Select the active monitors
Use the 'Select
by Attribute'
tool to select the active ozone monitors. Once selected, they
should be highlighted. Look in the attribute table and
scroll down to
see which ones are selected. You can click on the 'Selected'
button in the attribute table window to only see the selected ones.
2.) How many monitors are
active?_________________________________________
Step 3 Make a new layer from the selection
Using the selection from above, save it as a
new layer. It should create a layer with the word 'selection'
at the end.
3.) Does this method create redundant data?__________ Why
or why not?__________________
_________________________________________________________________________________
Step 4 Use a definition query
Step 3 created the layer of active sites, now create a definition query to limit
the original
ozone monitors layer (the one without
the word 'selection' in the name) to only inactive monitors. You should
end up with two ozone monitor layers in your data frame - one with
active sites (the 'selection' layer) and one with inactive sites (the
'original' layer now limited by a definition query).
4.) If someone else were to add a new active ozone monitor
location to the data, would it show up the next time you opened your
map?_____ Why or why
not?_________________________________________________________
5.) If someone else were to add a new inactive ozone monitor
location to the data, would it show up the next time you opened your
map?_____ Why or why
not?__________________________________________________________
Step 5 Changing symbols
Change the symbol
of the active
ozone monitors to a red circle, size 12.
Repeat steps 2-4
for the other data frame (so they look the same).
Step 6 Changing layer names
In both data frames, change the
name of
the 'selection' layer to 'Active ozone monitors' and change the name of the other
monitor layer
to 'Inactive ozone monitors'.
Step 7 Labeling
Label the active
monitors
layer (the 'selection' layer). Use automated labeling and use the
'CommonName' field for
labeling. Do this for the 'selection' layer in each data
frame. Use 'Arial' font, size 12, bold for the labels.
Challenge In step 4
above, what would happen in your map if someone else were to change the
status of a monitor from active to inactive?____________________________
With that in mind, is it preferable to use a selection
layer or a definition
query when
limiting a layer based on an attribute
field?______________________________________________
Remove the selection layer from each data frame and recreate them using
a definition
query instead. There are a few ways to do this.
Answers
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