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Append

Summary

Appends multiple input datasets into an existing target dataset. Input datasets can be feature classes, tables, shapefiles, rasters, annotation or dimensions feature classes.

To combine input datasets into a new output dataset, use the Merge tool.

Illustration

Append illustration

Usage

  • Use this tool to add new features or other data from multiple datasets into an existing dataset. This tool can append point, line, or polygon feature classes, tables, rasters, annotation feature classes, or dimensions feature classes into an existing dataset of the same type. For example, several tables can be appended to an existing table, or several rasters can be appended to an existing raster dataset, but a line feature class cannot be appended to a point feature class.

  • The Field Map parameter in the Append tool can be used to control how the attribute information from the input dataset fields is transferred to the target dataset. The Field Map parameter can only be used if Use the Field Map to reconcile schema differences is chosen for Schema Type.

  • This tool will not planarize features when they are added to the target dataset. All features from both the input feature class and the target feature class will remain intact after the append, even if the features overlap. To combine, or planarize, feature geometries, use the Union tool.

  • If Input schema must match target schema is chosen for Schema Type (schema_type = "TEST" in Python) , the schema (field definitions) of the input datasets must match that of the target dataset for the features to be appended. If Use the Field Map to reconcile schema differences is chosen (schema_type = "NO_TEST" in Python), the input dataset schema (field definitions) do not have to match the target dataset. However, any fields from the input datasets that do not match the fields of the target dataset will not be mapped to the target dataset unless the mapping is explicitly set in the Field Map parameter.

  • Because the input datasets' data is written to an existing target dataset that has a predefined schema (field definitions), the Field Map parameter does not allow for fields to be added or removed from the target dataset.

  • If the spatial references of an input and target feature class do not match, the Append tool will project the features in the input feature class to the coordinate system used by the target feature class.

  • This tool does not perform edge matching; there will be no adjustment to the geometry of features.

  • Map layers can be used as Input Datasets. If a layer has a selection, only the selected records (features or table rows) are used by the Append tool.

  • This tool cannot use multiple input layers with the same name. To work around this limitation, use the tool dialog box browse button to browse for the full paths of each of the Input Datasets.

  • To use the Subtype parameter, the target dataset must have a defined subtype field and assigned subtype codes. In the Subtype parameter, provide a subtype description to assign that subtype to all new data that is appended to the target dataset.

Syntax

Append_management (inputs, target, {schema_type}, {field_mapping}, {subtype}, {expression})
ParameterExplanationData Type
inputs
[inputs,...]

The input datasets containing the data to be appended to the target dataset. Input datasets can be point, line, or polygon feature classes, tables, rasters, annotation feature classes, or dimensions feature classes.

Tables and feature classes can be combined. If a feature class is appended to a table, attributes will be transferred, but the features will be dropped. If a table is appended into a feature class, the rows from the input table will have null geometry.

Table View; Raster Layer
target

The existing dataset where the input datasets' data will be appended.

Table View; Raster Layer
schema_type
(Optional)

Specifies whether the schema (field definitions) of the input datasets must match the schema of the target dataset for data to be appended.

  • TESTInput dataset schema (field definitions) must match the schema of the target dataset. An error will be returned if the schemas do not match.
  • NO_TESTInput dataset schema (field definitions) do not have to match the schema of the target dataset. Any fields from the input datasets that do not match the fields of the target dataset will not be mapped to the target dataset unless the mapping is explicitly set in the Field Map parameter.
String
field_mapping
(Optional)

Controls how the attribute fields from the input datasets are transferred or mapped to the target dataset. This parameter can only be used if the schema_type parameter is NO_TEST.

Because the input datasets' data is appended to an existing target dataset that has a predefined schema (field names and types), fields cannot be added or removed from the target dataset. You can set merge rules for each output field.

Merge rules allow you to specify how values from two or more input fields are merged or combined into a single output value. There are several merge rules that determine how the output field is populated with values.

  • First—Use the input fields' first value.
  • Last—Use the input fields' last value.
  • Join—Concatenate (join) the input fields' values.
  • Sum—Calculate the total of the input fields' values.
  • Mean—Calculate the mean (average) of the input fields' values.
  • Median—Calculate the median (middle) of the input fields' values.
  • Mode—Use the value with the highest frequency.
  • Min—Use the minimum value of all input fields' values.
  • Max—Use the maximum value of all input fields' values.
  • Standard deviation—Use the standard deviation classification method on all input fields' values.
  • Count—Find the number of records included in the calculation.

You can use the ArcPy FieldMappings class to define this parameter.

Field Mappings
subtype
(Optional)

The subtype description to assign to all new data that is appended to the target dataset.

String
expression
(Optional)

The SQL expression used to select a subset of the input datasets' records. If multiple input datasets are specified, they will all be evaluated against the expression. If no records match the expression for an input dataset, no records from that dataset will be appended to the target.

For more information on SQL syntax, see SQL reference for query expressions used in ArcGIS.

SQL Expression

Code sample

Append example 1 (Python window)

The following Python window script demonstrates how to use the Append tool in immediate mode.

import arcpy
arcpy.env.workspace = "C:/data/"
arcpy.Append_management(["north.shp", "south.shp", "east.shp", "west.shp"], 
                        "wholecity.shp", "TEST")
Append example 2 (stand-alone script)

The following script demonstrates how to use the Append tool.

# Name: Append.py
# Description: Use the Append tool to combine several shapefiles

# import system modules 
import arcpy
import os

# Set environment settings
arcpy.env.workspace = "C:/data"

# Set local variables
outLocation = "C:/Output"
outName = "MA_towns.shp"
schemaType = "NO_TEST"
fieldMappings = ""
subtype = ""

# Process:  Create a new empty feature class to append shapefiles into
emptyFC = arcpy.CreateFeatureclass_management(outLocation, outName, "POLYGON", 
                                              "amherst.shp")

# All polygon FCs in the workspace are MA town shapefiles, we want to append 
# these to the empty FC. The list will resemble ["amherst.shp", "hadley.shp", 
# "pelham.shp", "coldspring.shp"] 

fcList = arcpy.ListFeatureClasses("", "POLYGON")

# Create FieldMappings object to manage merge output fields
fieldMappings = arcpy.FieldMappings()

# Add the target table to the field mappings class to set the schema
fieldMappings.addTable(emptyFC)

# Add input fields for the town name into TOWNNAME field that matches the 
# target dataset since each input dataset has a different field name for 
# this info
fldMap = arcpy.FieldMap()
fldMap.addInputField("amherst.shp","TOWNNAME")
fldMap.addInputField("hadley.shp","NAME")
fldMap.addInputField("pelham.shp","TOWN_NAME")
fldMap.addInputField("coldspring.shp","TOWN")

# Set name of new output field "TOWNNAME"
townName = fldMap.outputField
townName.name, townName.aliasName, townName.type = "TOWNNAME", "TOWNNAME", "TEXT"
fldMap.outputField = townName

# Add output field to field mappings object
fieldMappings.addFieldMap(fldMap)

# Do the same thing for the POPULATION field
fldMap = arcpy.FieldMap()
fldMap.addInputField("amherst.shp","POPULATION")
fldMap.addInputField("hadley.shp","POP")
fldMap.addInputField("pelham.shp","POP_2010")
fldMap.addInputField("coldspring.shp","POP")

# Set name of new output field "POPULATION"
pop = fldMap.outputField
pop.name, pop.aliasName, pop.type = "POPULATION", "POPULATION", "LONG"
fldMap.outputField = pop

# Add output field to field mappings object
fieldMappings.addFieldMap(fldMap)

# Process: Append the feature classes into the empty feature class
arcpy.Append_management(fcList, os.path.join(outLocation, emptyFC), schemaType, 
                        fieldMappings, subtype)

Licensing information

  • ArcGIS Desktop Basic: Yes
  • ArcGIS Desktop Standard: Yes
  • ArcGIS Desktop Advanced: Yes

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