Using Expressions to Label Features
Creating Expressions
Troubleshooting Validation Errors
Using Expressions In Split/Merge Rules
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In AutoCAD Map 3D, you can set rules for the assignment of properties when you split and merge geospatial features. You can use expressions to define these rules.
For example, if you are splitting a parcel, you can specify that the land value of the resulting parcels be based on a calculation that you define. There are also choices for automatic calculations, such as assigning the average value of all merged features to the resulting feature, or dividing the value of a feature evenly among all its split features.
This table lists all the split and merge rule options and describes how to use them.
| Split Rules | Merge Rules |
|---|---|
| Copy gives each new feature an exact copy of the original property value. The original is unchanged. | Average gives the new feature a value that is an average of the original features. This option is for numeric values only. |
| Divide gives each resulting feature an equal fraction of the original value. This option is for numeric values only. | Count gives the new feature the value of the total number of features merged to produce it. This option is for numeric values only. |
| Empty leaves the new property value empty for each new feature. The original is unchanged. | First gives the new feature the value of the first feature you select for the merge. This option is meaningful only if you select the objects for the merge sequentially. (First is the default for all properties except numeric ones.) |
| Proportional divides the value of the property for each resulting feature proportionally, based on a value you specify. For example, you can assign a proportional value for Parcel_Acres based on the value of the area of the resulting parcels. This option is for numeric values only. | Last gives the new feature the value of the last feature you select for the merge. This option is meaningful only if you select the objects for the merge sequentially. |
| Calculation divides the value of the property for each resulting feature based on an expression you specify. For example, you can specify that Land_Value for each resulting parcel be equal to 2000 times the value of the property Parcel_Acres, if that’s the average property value for that neighborhood. This option is for numeric values only. | Maximum gives the new feature the maximum value available in all features in the merge. (This option is available for numeric properties only.) |
| Median gives the new feature the median value calculated from all features in the merge. (This option is available for numeric properties only.) | |
| Minimum gives the new feature the minimum value available in all features in the merge. (This option is available for numeric properties only.) | |
| Standard Deviation gives the new feature the standard deviation value calculated from all features in the merge. (This option is available for numeric properties only.) | |
| Sum gives the new feature the total value of all features in the merge. (This option is available for numeric properties only.) | |
| Calculation determines the value of the property for the resulting feature based on an expression you specify. For example, you can specify that Net_Value for each resulting parcel be equal to Land_Value minus Imp_Value. (This option is available for numeric properties only.) | |
| Concatenation appends the values for each merged feature to create the value for the new feature. |