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Analysis I: Selection
And an introduction to planning an analysis
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Topics
• Selection and its booby traps• A Project• Demo
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Selection
• Three ways to select…– Manual using the tool– Select by Attribute– Select by Location
• Booby Trap
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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 AttributeRight Layer?List only selectable FCsKind of selectionFields 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 unselectedUnselected Selected
Selected = NOT(selected)
Where?
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Plan
TAX
AREA OKCLS OK
Export
attribute
CLS OK AREA OK
BOTH OK
INTERSECT
CLS OK
TAX
BOTH OK
NEW SET attribute
Sel from sel’ed setArea 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