🛠️ Update

Purpose: > Update is similar to Union in extent but in the area where the two layers overlap, only the geometry and attributes of update layer is retained.

🎭 Illustration

update

📋 Technical Specifications

Requirement Detail
Input Feature Types {Polygon}
Output Feature Type Polygon
Map Name 05.Update
inputs GDB 05.input_update.geodatabase
output GDB 05.output_update.geodatabase

🧠 Logic & Arithmetic Operation

Logic: $A \cap (B-A)$

⚙️ Parameters & Conditions

Input Parameter: Input Features

Overlay Parameter: Update Features

Geometry: Polygon

No. of Inputs: Two or more

Order: matters

Coordinate System: Same as 1st input layer

🚩 Key Notes

  • The Update tool works similarly to Union, but with stricter rules:
    • Both input and update layers must be polygons.
    • The output is polygon in nature.
  • Unlike Union, interchanging input and update layers produces different results:
\[A \; \text{Update} \; B \neq B \; \text{Update} \; A\]
  • This gives two possible combinations to start with, depending on which layer is chosen as input vs. update.

🐍 Arcpy Function 

arcpy.analysis.Update(in_features, update_features, out_feature_class, {keep_borders}, {cluster_tolerance})

for more on function parameters, check: Arcpy Documentation Here.

🖼️ Figures

Inputs Output AB Output BA
A B Res