定时执行Python脚本或模型

At the Spatial Analysis and Geoprocessing island at this year’s user conference, several folks asked us about running a Python script or ModelBuilder model at a prescribed time — usually in the early morning when their computers are bored and just waiting for something to do. We thought it would be good to make a post about this and to share some tips.

The first place to start is with the help topicScheduling a Python script to run at prescribed times. This topic is kind of buried in the help system so it’s easy to miss. The meat of this topic shows you how to launch Window’sTask Scheduleron various operating systems (Windows 7, XP, and so on). The screenshot below shows theTask Scheduleron Windows 7. There’s a lot stuff you can do with the task scheduler and you’ll just have to play around with it and read the Windows help. TheActionspane, on the right, has theCreate Basic Taskaction, and this is the place to start.

Clicking onCreate Basic Taskopens a wizard where you define the name of your task, thetrigger(when it runs), and theaction(what program to run). The screenshot below shows theActiontab where you specify the name of your Python script to run as well as any arguments to the script.

TheActiontab is where we have a few tips, as follows.

Run the Python executable with arguments

To ensure that your Python script will run regardless of the login account that the schedule task uses, and to avoid any confusion about which version of Python is used in mixed environments (64bit or 32bit), we recommend that you run the Python executable with the name of your Python file as an argument to the executable.

Suppose the script you want to run isE:\My script.py. Instead of running the script directly, instruct the task scheduler to runpython.exewith the script as an argument. For example:

C:\Python27\ArcGIS10.2\python.exe "E:\My script.py"

The location ofpython.exedepends on your install. If you don’t know where it is, you can discover its location; copy and paste the following code into a new Python script then execute the script. The script will print the location ofpython.exeas well as other information about your Python environment.

import sys
import platform
import imp
 
print("Python EXE     : " + sys.executable)
print("Architecture   : " + platform.architecture()[0])
print("Path to arcpy  : " + imp.find_module("arcpy")[1])
 
raw_input("\n\nPress ENTER to quit")

After determining the location ofpython.exe, this is what is entered in theActionpanel of the task scheduler:

If there are additional arguments (parameters) to your script, provide them after the path to your script. For example, the following command line executes a Python script that takes two arguments; the path to a feature class and an integer.

C:\Python27\ArcGIS10.2\python.exe "E:\My Scripts\DoConversion.py" c:\gisWork\gdb.mdb\counties 10

We typically recommend writing scripts so that they take arguments like the above example rather the hard-coding dataset paths or values within the script. However, this is one case where hard-coding paths and values in your script works to your advantage; rather than changing argument values in the task scheduler, it’s easier to just edit your script to use different paths or values.

If you’re familiar with.batfiles in Windows, you can have the task scheduler run a.batfile that in turn runs your script with arguments. The contents of the.batis the single command line shown above.

Remember that if any of your arguments contain spaces, you need to enclose the argument in double quotes. In the above example,E:\My Scripts\DoConversion.pycontains a space, so double quotes are required.

Running models at a prescribed time

A common misconception is that in order to run a model as a Python script, you must first export the model to a Python script. Geoprocessing is designed so that models are tools, just like all the tools delivered with the ArcGIS. That means you can run your model within Python just like any other geoprocessing tool. All you need to do is import the toolbox containing your model using theImportToolboxfunction, then run your model within Python.

For example, the model to the left imports a.gpxfile to a geodatabase, adds a field, calculates it to the current date and time, then appends all those features into a “master” feature class.

To run this model on a schedule, all that’s needed is to execute the model within a script. Here’s the Python script to run the model:

importarcpy
importos
fromdatetime importdatetime
 
# Import the toolbox containing the model.  This toolbox
#  has an alias of "gpxtools"
#
arcpy.ImportToolbox(r"c:\importgpx\myGPXstuff.tbx")
 
# Run the model.  The model has two parameters, the input
#  .gpx file and the feature class to update
#
arcpy.ImportGPX_gpxtools(r"c:\ftp\inbox\datadrop.gpx",
                         r"c:\ftp\server.sde\gpx_tracks")
 
# Now that is has been processed, rename input gpx
#   to have the date and time.
#
os.rename(r"c:\ftp\inbox\datadrop.gpx",
          r"c:\ftp\inbox\datadrop{}.gpx".format(datetime.strftime(datetime.now(),"%Y%m%d"))

Advanced options

TheCreate Basic Taskwizard allows you to set basic properties of the task. Once the task is created, you can examine its properties and refine its triggers and actions. For example, you can have your task run every five minutes for three hours. You can set up a task with advanced options using theCreate Taskaction.

Start simple

When I started writing this blog, it had been a long time since I messed around with scheduled tasks, so I started with a simple script that wrote information to a log file. I scheduled it to run every minute for ten minutes so I could test changes to the script soon after I made them. It was a great way to test and understand how scheduling worked before committing to running the “real” script. Here’s my simple script:

importsys
importplatform
importimp
print"Importing arcpy... this may take a moment\n"
importarcpy
 
# Open a log file to write to
#
f=open(r'E:\schedule.log','w')
 
# Write date/time
#
f.write(time.strftime('%x %X'))
f.write('\n')
 
# Test receiving of arguments/parameters via arcpy
#
f.write("Parameter 0 : " + arcpy.GetParameterAsText(0)+"\n")
 
# Python info
#
f.write("Python EXE : " + sys.executable +"\n")
f.write("Architecture : " + platform.architecture()[0]+"\n")
f.write("Path to arcpy : " + imp.find_module("arcpy")[1]+"\n")

Ghislain Prince contributed to this post