Arcmap field calculator
The arcgis.rand() function is supported by this tool when a Python expression is specified. To calculate a field to be a numeric value, enter the numeric value in the Expression parameter no quotation marks around the value are required.
However, if the character string has embedded single quotation marks, wrap the string using double quotation marks, for example, = "TYPE'A'". Expressions using a character string should be wrapped, using single quotation marks, for example, = 'NEW STRING'.
Arcmap field calculator update#
This tool can also be used to update character items. To calculate strings to text or character fields, in the dialog box the string must use double quotation marks ("string"), or in scripting, the string using double quotation marks must also be encapsulated in single quotation marks ('"string"'). A copy of the input table should be made if you want to preserve the original values.įor Python calculations, field names must be enclosed in exclamation points ( !fieldname!).įor VB calculations, field names must be enclosed in square brackets ( ). The calculation can only be applied to one field per operation.Įxisting field values will be overwritten. When used with a selected set of features, such as those created from a query in Make Feature Layer or Select Layer by Attribute, this tool will only update the selected records. Python expressions can be used to calculate the geodesic area or length of a feature by using geodesicArea or geodesicLength properties combined with areal or linear units of measure (for example, or the tool dialog box, an expression can be entered directly into the Expression parameter or interactively built using the Field Calculator.
ACRES | ARES | HECTARES | SQUARECENTIMETERS | SQUAREDECIMETERS | SQUAREINCHES | SQUAREFEET | SQUAREKILOMETERS | SQUAREMETERS | SQUAREMILES | SQUAREMILLIMETERS | SQUAREYARDS | SQUAREMAPUNITS | UNKNOWN.Using areal units on geographic data will yield questionable results as decimal degrees are not consistent across the globe. Python expressions can use the geometry area and length properties with an areal or linear unit to convert the value to a different unit of measure (for example, If the data is stored in a geographic coordinate system and a linear unit is supplied (for example, miles), the length will be calculated using a geodesic algorithm. Python expressions can be created using properties from the Geometry object including type, extent, centroid, firstPoint, lastPoint, area, length, isMultipart, and partCount (for example, !shape.area!).