GEOPROCESARE IN ARCGIS FOLOSIND PYTHON

UNIVERSITATEA DE VEST DIN TIMISOARA

DEPARTAMENTUL DE GEOGRAFIE

SUPORT DE CURS SI APLICATII PRACTICE

MASTER: SISTEME INFORMATIONALE GEOGRAFICE

AUTOR:

OVIDIU CSILLIK

CUPRINS

INTRODUCERE

ARCPY SI PYTHON

GEOPROCESSING TOOLS

REGULI DE SCRIERE A SCRIPTURILOR

NOTIUNI DE BAZA PYTHON

EXERCITII

DEPANAREA UNUI SCRIPT

EXEMPLU DE COD PYTHON

FUNCTII SI PROPRIETATI AVANSATE

FUNCTII DESCRIPTIVE

FUNCTII DE LISTA

FUNCTII CURSOR

FUNCTII DE GEOMETRIE

CREAREA UNEI UNELTE IN ARCTOOLBOX

MAPPING MODULE

MANIPULAREA HARTILOR SI A LAYERELOR

CE ESTE ARCPY ?!?

ArcPy este succesorul modulului arcgisscripting.

Crearea unei baze folositoare si productive pentru:

• analiza datelor geografice

• conversiilor de date

• managementului de date

• automatizarii crearii hartilor cu ajutorul Python.

>>> import arcpy

>>> help(arcpy)

ARCPY SI PYTHON

• Unelte de geoprocesare automate

• Cautare in inregistrari, citirea si scrierea valorilor specifice

• Manipularea documentelor de harta si layere

• Crearea si manipularea geometriei

UNDE EXECUTAM CODURILE PYTHON ?!? Editorul PythonWin

Python 2.6.5 IDLE

Fereastra Python din ArcMap

UNDE EXECUTAM CODURILE PYTHON ?!?

Field Calculator - ArcMap Script in Toolbox

GEOPROCESSING TOOLS IN ARCGIS

Toolbox Name Alias

Analysis Toolbox analysis

Cartography Toolbox cartography

Conversion Toolbox conversion

Coverage Toolbox arc

Data Management Toolbox management

Geocoding Toolbox geocoding

Geostatistical Analyst Tools ga

Linear Referencing Toolbox lr

Network Analyst Tools na

Samples samples

Spatial Analyst Toolbox sa

Spatial Statistics Toolbox stat

3D Analyst Toolbox 3d

ACCESSING ENVIRONMENT SETTINGS VIA ARCPY

Environment settings as properties from arcpy.env class: import arcpy # setting the environment: object.properties = value arcpy.env.workspace = "C:\\temp" arcpy.env.cellSize = 100 # retrieve settings: result = object.properties variableWorkspace = arcpy.env.workspace print "the name of the workspace is: " + variableWorkspace print "cell size is: " + " arcpy.env.cellSize

ACCESSING TOOLS VIA ARCPY

Tools can be accessed as functions directly from arcpy

import arcpy

arcpy.env.workspace = "C:\\temp"

# Tool access follows (usually) the following scheme:

# object.Tool (parameter 1, parameter 2, parameter n)

arcpy.Buffer_analysis (InFeature, "c:\\ buff.shp", 100)

input feature class – output - buffer value

BINE DE STIUT

• Comentariile din interiorul scriptului : #

• Numele de variabile nu pot incepe cu o cifra

• Case sensitive:

• Variables names

• Statements

• Functions

• Geoprocessing function and class names

• Not case sensitive:

• Pathnames

PENTRU CURIOSI

Books

• Learning Python, (4th Edition) by Mark Lutz

• Learn to Program Using Python by Alan Gauld

• Programming Python by Mark Lutz

Web sites

• www.python.org

• Tutorials, documentation, forums

• diveintopython.org

• Online tutorial book

• http://code.activestate.com/recipes/langs/python/

• Learn Python functionality, share sample non-GIS Python scripts

NOTIUNI DE BAZA - PYTHON

Tipuri de date

• Variabilele pot stoca valori de diferite tipuri

NOTIUNI DE BAZA - PYTHON

Statements

• Indeplinesc o sarcina, dar nu returneaza o valoare

• Importarea modulelor in script

• Printarea stringurilor in fereastra interactiva

NOTIUNI DE BAZA - PYTHON

Statements

• Indeplinesc o sarcina, dar nu returneaza o valoare

• Testarea daca o conditie e True sau False

• Bucla de cautare intr-o colectie

FII PE FAZA !

Gaseste 3 erori in scriptul de mai jos:

Gaseste 4 erori in scriptul de mai jos:

if x = 5:

print "x is equal to 5"

elif x > 5

print "x is greater than 5"

else:

print "x is not equal to or greater than 5'

# This script buffers the Railroads feature class from the

# SanDiego.gdb geodatabase. The buffer distance is 500 meters

import arcpy

arcpy.env.Workspace = "C:\Student\\PYTH\\Database\\SanDiego.mdb"

inFC = "Railroads"

distance = 500

arcpy.Buffer_analysis(inFC, newBuffFC, distance)

FII PE FAZA !

Gaseste 5 erori in scriptul de mai jos:

# This script prints each item in the Python list to the

# Interactive Window.

listFC = ["Airports", "BusStations", "Schools", "Parcels"]

For fc in listFc:

print fc

Print len(lstFc)

FII PE FAZA !

Gaseste 3 erori in scriptul de mai jos:

# This script compares the square root of 25 with 6 and

# reports the comparison to the Interactive Window.

Import math

z = 25

y = 6

x = math.sqrt(z)

if x = y:

print "x and y are the same"

elif x > y:

print "x is greater than y"

else

print "x is less than y"

DEBUGGING WORKFLOW

Check for syntax errors

1

Run with arguments

2

Comment out code

3

Use print statements

4

Use Debugging Toolbar

5

EXEMPLU PYTHON

Statement

Variabila Lista

Bucla FOR

PYTHON – FIELD CALCULATOR

FUNCTII SI PROPRIETATI AVANSATE

Proprietati si functii suplimentare, ce nu se gasesc in ArcToolbox

FUNCTII SI PROPRIETATI AVANSATE

Proprietati si functii suplimentare, ce nu se gasesc in ArcToolbox

FUNCTII DESCRIPTIVE

Extrag informatii despre date pentru luarea deciziilor

• Shape, Raster, Tabele, Workspace etc.

Linie

Numele campului

Tipul: integer, string etc.

FUNCTII DE LISTA

Obtinerea unei lista cu shape, rastere sau tabele

• Adaugarea intr-o geodatabase prin cautarea de .shp intr-o lista

Geodatabase os.sep = \ # print os.sep

rstrip returneaza o copie a stringului din

care taie “.shp” # gaseste toate .shp

FUNCTII CURSOR

Acceseaza o colectie de inregistrari

• Citeste si scrie valori in timpul iteratiilor fiecarei inregistrari pe rand

FUNCTIA SEARCHCURSOR

Row(s)

#Set current workspace

arcpy.env.workspace = "C:/Student/PYTH/Database/SanDiego.gdb"

#Create cursor on MajorAttractions feature class

curs = arcpy.SearchCursor("MajorAttractions")

# Iterate through the rows in the cursor

# Print the name and Address of each Major Attraction

for row in curs:

print row.Name

print row.Addr

del curs, row

SearchCursor (parameters)

Cursor Task

Reading

FUNCTIA UPDATECURSOR

#Set current workspace

arcpy.env.workspace = "C:/Student/PYTH/Database/SanDiego.gdb"

#Create cursor on MajorAttractions feature class

curs = arcpy.UpdateCursor("MajorAttractions",

'"NAME" = \'San Diego Zoo\'')

# Iterate through the rows in the cursor and update the address

for row in curs:

row.Addr = "1900 ZOO PLACE"

cur.updateRow(row)

del curs, row

Row(s) UpdateCursor (parameters)

Cursor Task

Updating

FUNCTIA INSERTCURSOR

#Set current workspace

arcpy.env.workspace = "C:/Student/PYTH/Database/SanDiego.gdb"

#Create cursor on MajorAttractions feature class

curs = arcpy.InsertCursor("MajorAttractions")

# Create new row, update fields and insert row.

row = curs.newRow()

row.Name = "BLACK MOUNTAIN PARK"

row.Addr = "12115 BLACK MOUNTAIN RD"

curs.insertRow(row)

del curs, row

row New

Row InsertCursor

(parameters)

Cursor Task

Insert

GEOMETRIA OBIECTELOR

Creare, stergere, mutare sau remodelarea caracteristicilor

SCRIPT TOOL

Adaugarea unui script ca o unealta in ArcToolbox

• Un tool de geoprocesare care executa un script

• Full membership in geoprocessing framework

• Communicates with ArcGIS applications:

• Messages

• Environments

• Outputs added to map

• Etc.

SCRIPT TOOL

Avantaje

• Sunt usor de share-uit

• Utilizabile si de incepatori (creaza automat casute de dialog)

• Pot fi adaugate in Bara de unelte

• Inserarea scriptului intr-un Model

ARCPY FUNCTION: GETPARAMETERASTEXT

ArcPy function: GetParameterAsText

Function directly accessible through ArcPy

Used to capture input parameters

• This method can only be used with ArcToolbox. Not for use with PythonWin or Command Prompt

Zero based. First argument is at position 0, and each argument thereafter is incremented by one.

import arcpy

# GetParameterAsText function (numbered for each parameter)

arcpy.env.workspace = arcpy.GetParameterAsText(0)

bufFC = arcpy.GetParameterAsText(1)

bufOut = arcpy.GetParameterAsText(2)

bufDist = arcpy.GetParameterAsText(3)

arcpy.Buffer_analysis(bufFC, bufOut, bufDist)

DISPLAY ERROR MESSAGE / INFORMATION MESSAGES IN ARCGIS

Show error or information messages in the Python Editor:

print statement (only valid in the Python Editor and/or the Python execution window)

and/or

print arcpy.GetMessages() # retrieves ArcGIS/ArcPy specific messages

Show error or information messages in ArcGIS (if a script is executed as a tool):

AddMessage(Message string) # like the print statement

AddWarning(Message string)

AddError(Message string)

• Difference in appearance

Display explicit errors in ArcGIS: arcpy.AddMessage(arcpy.GetMessages())

ATTACH A SCRIPT TO A CUSTOM TOOL

General properties

Script location

Parameter properties

MAPPING MODULE

arcpy.mapping

Python scripting library

• Open and manipulate map documents (.mxd), layer files (.lyr)

• Query and alter contents

• Print, export or save the modified document

Automate ArcMap workflows

• Map management, output

• Update or repair data source

• Create a report

• Build a variety of PDF map books

MANIPULATE MAP DOCUMENTS AND LAYERS

Add, remove and rotate data frames

Add, remove layers

Set properties

DATA FRAME Referinta spatiala Extend Etc.

‘Curent’

MANIPULATE MAP DOCUMENTS AND LAYERS

Add, remove and rotate data frames

Add, remove layers

Set properties

LAYER Name, Source, Label, Visibility, Transparency Etc.

SUMAR – GEOPROCESARE FOLOSIND ARCMAP SI PYTHON

Geoprocessing is for everyone that uses ArcGIS.

Whether you're a beginning user or a pro, geoprocessing will become an essential part of your day-to-day work with ArcGIS.

The fundamental purposes of geoprocessing are to allow you to automate your GIS tasks and perform spatial analysis and modeling.

Almost all uses of GIS involve the repetition of work, and this creates the need for methods to automate, document, and share multiple-step procedures known as workflows.

SUMAR – GEOPROCESARE FOLOSIND ARCMAP SI PYTHON

Geoprocessing supports the automation of workflows by providing a rich set of tools and a mechanism to combine a series of tools in a sequence of operations using models and scripts.

Geoprocessing is based on a framework of data transformation. A typical geoprocessing tool performs an operation on an ArcGIS dataset (such as a feature class, raster, or table) and produces a new dataset as the result of the tool. Each geoprocessing tool performs a small yet essential operation on geographic data, such as projecting a dataset from one map projection to another, adding a field to a table, or creating a buffer zone around features. ArcGIS includes hundreds of such geoprocessing tools.

MULTUMESC PENTRU

ATENTIE

DONE !