Calculate Geometry Using Python - NWCG

8/30/18

Calculate Geometry Using Python

ArcGIS Pro

The Calculate Geometry function is only available in ArcGIS Pro 2.2+. When using an older version to calculate feature geometries to existing fields, a Python expression must be used.

Calculate Acreage

These calculations will depend on the spatial reference of the feature class, not the data frame. 1. Open the layer properties by right-clicking the map in the table of contents and selecting Properties. 2. Check the layer Spatial Reference to be sure it has the WGS84 Geographic Coordinate System.

Layer Properties: Event Polygon

X

Genera l Metadata Source Elevation Selection Display

"'Spatial Reference

Geographic coordinate system GCS WGS 19B4

WKID

43-26

Authority

EPSG

Angular Unit

Degree (0,017453292519'9433]

3. Open the Event Polygon attribute table, right-click the Acres field, and select Calculate Field. Alternatively, click Calculate and select Acres as the field name in the Geoprocessing pane.

!E:! Event Poly gon X

Field:

le Calculate

..d Map M ethod

Comments

l

< Nul l>

Click to add new row.

rJ Selection: ~Zoom To

Switch ~ Clear ~ Delete

Delete this featu re? Label

Fe

Sort Ascending

Co

i,,1, Sort .Qescending

3) S:.ustom Sort.. ,

Hide Field

Calculate Field ummanze

~ ? 1 of 1 se[ected

Fields ~ Delete

Calculate Geometry Using Python - 1

8/30/18

4. Enter !shape.geodesicArea@acres! into the expression field and click Run.

Geo p rocess ing

?

Calcu late Field

.... i, X

-

Pararneters Environments.

?

Input Table

IEvent Polygon

~1 +

Field Name

I Acres

~1

* Expres:si on

Fields:

OBJECTID SHAPE

T Helpers

'f

I.... .conjugate0 .denomi?nator0

....

I

SHAP E_Len gth

.imag o

SHAPE_Area

.numerator0

Incident Name

.real 0

Feature Category (P .as_integer_ratio 0

.,. Collector Name

M,mMPi"hnrl

.fromhex0

.h,;,1d't

.,.I..J

Insert Values-

... I +

G15Acres =

I J!shape . geodesicArea@ac r es!

Code Block

5. The Acres field will now be populated.

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m n Fie!d: ~ !9

Selection,:

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Elj:

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Co mments.

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Acres. I elete t his featu r

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1324.799153 ~ p

- Click to add new row.

Run ~

Calculate Geometry Using Python - 2

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Calculate Line Lengths These calculations will depend on the spatial reference of the feature class, not the data frame.

1. Open the layer properties by right-clicking the map in the table of contents and selecting Properties.

2. Check the layer Spatial Reference to be sure it has the WGS84 Geographic Coordinate System.

Layer Properties: Ev ent Line

X

General Meta.data Source

Elevation

Selection

Display

....

"'SpaUal Reference

Geog raphic coordinate system GCS WGS 1984

WKID

4326

Authority

EPSG

Angular Unit

Degree (0.0174532925199433]

3. Open the Event Line attribute table, right-click the LengthFeet field, and select Calculate

Field. Alternatively, click Calculate and select LengthFeet as the field name in the

Geoprocessing pane.

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Field: l,i Add [9 Deletej IP.:tJ Calculate JSelectiolil: "el

n !r'e:li Switch

~ dentlD UnitlD -

I_

COABC

GeometrylD

I Length EePt- II IRW IJ\llr'I

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