How to organize a Python GIS-project with multiple analysis steps? -

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i started use arcpy analyse geo-data arcgis. analysis has different steps, executed 1 after other.

here pseudo-code:

import arcpy  # create masking variable mask1 = "mask.shp"      # create list of raster files files_to_process = ["raster1.tif", "raster2.tif", "raster3.tif"]  # step 1 (e.g. clipping of each raster study extent) index, item in enumerate(files_to_process):         raster_i = "temp/ras_tem_" + str(index) + ".tif"         arcpy.clip_management(item, '#', raster_i, mask1)  # step 2 (e.g. change projection of raster files) ...  # step 3 (e.g. calculate statistics each raster) ...  etc.

this code works amazingly far. however, raster files big , steps take quite long execute (5-60 minutes). therefore, execute steps if input raster data changes. gis-workflow point of view, shouldn't problem, because each step saves physical result on hard disk used input next step.

i guess if want temporarily disable e.g. step 1, put # in front of every line of step. however, in real analysis, each step might have lot of lines of code, , therefore prefer outsource code of each step separate file (e.g. "step1.py", "step2.py",...), , execute each file.

i experimented execfile(step1.py), received error nameerror: global name 'files_to_process' not defined. seems variables defined in main script not automatically passed scripts called execfile.

i tried this, received same error above.

i'm total python newbie (as might have figured out misuse of python-related expressions), , thankful advice on how organize such gis project.

i think want build each step function. these functions can stored in same script file or in own module gets loaded import statement (just arcpy). pseudo code this:

#file 1: steps.py def step1(input_files):   # step 1 code goes here   print 'step 1 complete'   return  def step2(input_files):   # step 2 code goes here     print 'step 2 complete'     return output # optionally return derivative here  #...and on

then in second file in same directory, can import , call functions passing rasters inputs.

#file 2: analyze.py import steps files_to_process = ["raster1.tif", "raster2.tif", "raster3.tif"]  steps.step1(files_to_process)  #steps.step2(files_to_process) # uncomment when you're ready step 2

now can selectively call different steps of code , requires commenting/excluding 1 line instead of whle chunk of code. understood question correctly.


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