Analysis I: Selection
And an introduction to
planning an analysis
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Topics
• Selection and its booby traps
• A Project
• Demo
2
Selection
• Three ways to select…
– Manual using the
– Select by Attribute
– Select by Location
tool
• Booby Trap
3
Nitty-Gritty
•
•
•
•
Limiting what can be selected
Set it in Selection TOC tab
Or
In Selection menu / Set Selectable
Layers
• This is good practice because
• Doing this prevent you from selecting
the wrong layer
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Select by Attribute
Right Layer?
List only selectable FCs
Kind of selection
Fields in layer
Operation
SQL statement
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Booby Traps
• Not selecting from right layer
• Not paying attention to the selection
process
–
–
–
–
Create New Selection
Add to the current selection
Remove from the current selection
Select from the current selection
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Select by Attribute
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Select from current selection
• Still Tax Parcels
• But I want only
those parcels that
area >4.9 acresa
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Select by Location
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Analysis Options: Location
•
•
•
•
•
•
•
•
•
•
•
Intersect
Are within a distance of
Completely Contain
Are completely within
Have their centroid in
Touch the boundary of
Share a line segment with
Are identical to
Are crossed by the outline of
Contain
Are contained by
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Options: Intersect
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Options:Touch Bndy of…
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Options: Have their Center in…
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Options: Are completely w/in…
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Options: w/in a distance of…
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Options: are contained by…
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Options: are contained by…
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The Problem
• Ripemoff Power Co needs to…
– Find areas where, in Martinsburg, Willow
can be grown and harvested with farm
types of machinery
– The requirements are…
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TaxParcel Requirements
• Land USE must be Ag..
• Land Cover must be Ag
• Slope in the parcel . . .
must be everywhere
less than or equal to
8%.
• Tax parcels must be . .
50 acres or more
• No wetlands
• No ponds
.. Tax Parcel data [CLS]
.. Landsat data [grid code]
.. Slope from DEM &
processed into poly shape
.. TaxParcel data [acres]
… MartDECwet
…Ponds
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TaxParcel Requirements
• Land USE must be Ag..
• Land Cover must be Ag
• Slope in the parcel . . .
must be everywhere
less than or equal to
8%.
• Tax parcels must be . .
50 acres or more
• No wetlands
• No ponds
.. Select by Attribute
.. Select by Attribute
.. Complex raster
processing
.. Select by Attribute
… Select by location
…Select by location
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TaxParcel Requirements
• Land USE must be Ag..
• Land Cover must be Ag
• Slope in the parcel . . .
must be everywhere
less than or equal to
8%.
• Tax parcels must be . .
50 acres or more
• No wetlands
• No ponds
.. [cls]>=120 AND [cls] <200
.. [gridcode]=4
.. [slope>]=8
… [acres]>=50
… Switch selection
… Ditto
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Switch?
Selected unselected
Unselected Selected
Selected = NOT(selected)
Where?
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Plan
TAX
TAX
attribute
CLS OK
AREA OK
NEW SET attribute
CLS OK
Export
CLS OK
AREA OK
Sel from sel’ed set
Area ok
INTERSECT
BOTH OK
BOTH OK
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Summary
• Selection processing can solve a lot of
problems in analysis
• Booby traps abound – due on not
paying attention
• Choice of
– Saving the results of each operation
– Or using the “select from selected set”
trick
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