ArcGIS Python Mapping Module

Arc Python to interact with Arc-map

What is ArcPy Mapping and Why is it actually used for :

Arcpy.mapping was built for the professional GIS analyst (as well as for developers). Traditionally, the scenarios listed above had to be done using ArcObjects and it often proved to be a very difficult programming environment to learn for the average GIS professional. Arcpy.mapping is a courser-grained object model, meaning that the functions are designed in a way that a single arcpy.mapping function can replace many lines of ArcObjects code. The following is a very simple example of how arcpy.mapping can be used to reference an existing map document and export it to a PDF document with only two lines of code.

To explore the Overall Arcpy mapping Module use the following PDF:

Arcpy Python Mapping Module

Code for Getting the reference to the MXD :

YourMXD= arcpy.mapping.MapDocument("path to the MXD")

To export the above MXD to PDF using arcpy:

arcpy.mapping.ExportToPdf(YourMXD,"your pdf file")

Pointer to a MXD present on the Disk

Layout View of the Map Document

Arcpy.mapping is not a replacement for ArcObjects but rather an alternative for the different scenarios it supports. ArcObjects is still necessary for finer-grain development and application customization, whereas arcpy.mapping is intended for automating the contents of existing map documents and layer files.

Creating Geodatabases using Arcpy or Model builder

Creating Geo-databases in Arc Map

What is a Geodatabase:

• A geodatabase is the common data storage and management framework for all the ArcGIS Products. It combines Geo (spatial data) with Database (data repository) to create a central data repository for all the spatial data storage and management in your ArcGIS platform.
• It can be leveraged in desktop, server, or mobile environments and allows you to store GIS data in a central location for easy access and management.

The geodatabase offers you the ability to

• Store a rich collection of spatial data in a centralized location.
• Apply sophisticated rules and relationships to the data.
• Define advanced geospatial relational models (e.g., topologies, networks).
• Maintain integrity of spatial data with a consistent, accurate database.
• Work within a multiuser access and editing environment.
• Integrate spatial data with other IT databases.
• Easily scale your storage solution.
• Support custom features and behavior.
• Leverage your spatial data to its full potential.

Arc-map geodatabase can be created using various way:

1. Manually creating through Arc-Catalog
2. Using the Model workflow to create it Programmatic-ally
3. Using the Python integrated to Create Geodatabase Programmatic

1. Model for Creating Feature Class

Model to create Geodatabase in ArcGIS

Set the workspace and OutputFC as the Model parameter

AddField will add a column to the newly created Feature class and can be populated with the user defined values

The Search, Insert or Update cursor can be used to manipulate the values present in the new Feature class

For achieving the above functionality it is advised to write a python code using the arcpy library.

To know more detailed step by step information about the creating a feature class in the Geodatabase
Click here - Create Geodatabase Feature Class - PDF

Arcpy Improvements in 10.1

Arc Python in ArcGIS 10.1

1. Site package that adds ArcGIS functionality to Python
2. Access to rich suite of geoprocessing tools
3. Functions, classes and modules
4. Helper functions like ListFeatureClasses, Describe
5. Classes that can be used to create complex objects like Spatial Reference, Field Map
6. Modules that provide specialized functionality like Mapping,SpatialAnalyst, NetworkAnalyst, DataAccess

Complete Introduction to Python concepts for beginners is available here

ArcPython a complete Overview

ArcGIS + Python = ArcPython

For more info and advance Concepts use the folowing references: 

resources.ArcGIS.com

arcpy.wordpress.com

GIS Stack Exchange, Stack Overflow

Python References,Python Scripting for ArcGIS

GIS Tutorial for Python Scripting by Allen (Esri Press)

Learning Python by Lutz - The Python Standard Library

python.org

http://www.esri.com/training

Exporting the feature class to CSV Format

Exporting Geodatabase toComma Separated Value Format

Let start creating an python addin for converting the feature class in your geodatabase to CSV format.So that everyone can understand your feature class and its values.

• If you are very new to python addin then go through- How to start with python addin 
• The input feature class and output csv file path are hard coded in the sample program
• For dynamic conversion get the path of the files through a variable and pass it as a parameter to the defined functions

CSV Fromat

def ex_fc_to_csv(fc, out_csv):

    """

    Export all vertex in a line or poly feature class to a csv with OID

   

    example

        import geom_snippets

        geom_snippets.ex_fc_to_csv(r"c:\proj\fc1.shp", r"c:\proj\fc1.csv")

    output csv looks like this

        1,56019.99998067904,69118.00001450378

        1,56159.99998080942,69026.0000144181

        1,56359.999980995686,68913.00001431286

        2,34985.00002508866,68936.00001433428

        2,35178.000025268404,68805.00001421227

    """

    import csv

    import json

    with open(out_csv, 'w') as csvfile:

        csvwriter = csv.writer(csvfile, delimiter=',', lineterminator='\n')

        with arcpy.da.SearchCursor(fc,

                                   field_names=("OID@","SHAPE@JSON")) as cursor:

            for row in cursor:

                geom = json.loads(row[1])

                for path in geom['paths']:

                    for pt in path:

                        csvwriter.writerow([row[0]] + pt)

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