Transcript GRASS and PythonTesting v.transect.py

John Lloyd
MEA582 Fall 2011
Final Project
[email protected]
John Lloyd MEA582 Final Project
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Introduction
Environment Setup
◦ Linux
◦ Windows
◦ Running Python
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v.transects.py
Testing
◦ Methodology
◦ Test Cases
◦ Results

Conclusions
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Setup Linux and Windows Environments
◦ Built GRASS from source code
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Python script
◦ v.transects.py
◦ Script partitions the shoreline
◦ Written by Eric Hardin
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Tested script
◦ Linux
◦ Windows
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
Introduction
Environment Setup
◦ Linux
◦ Windows
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
v.transects.py
Testing
◦ Methodology
◦ Test Sets
◦ Results

Conclusions
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Linux and Windows
Built GRASS from source code
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Latest versions – not dependent on pre-built binaries
Debug problems by following execution in code
Add enhancements
Understand algorithms
GRASS Wiki http://grass.osgeo.org/wiki/Compile_and_Install
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CentOS Linux 5.7
◦ Free distribution of Enterprise Linux
◦ Installed groups for software development
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Downloaded prerequisite packages for GRASS
Downloaded GRASS source code
◦ (http://grass.osgeo.org/download/software.php
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Compiled and Installed
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Microsoft Windows7 Professional
OSGeo4W
◦ Installs binaries of open source geospatial software for
Windows
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MinGW – Minimalist GNU for Windows
◦ A Unix like environment for Windows
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Downloaded prerequisite packages for GRASS
Downloaded GRASS source code
Compiled and Installed
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

Introduction
Environment Setup
◦ Linux
◦ Windows
◦ Running Python


v.transects.py
Testing
◦ Methodology
◦ Test Sets
◦ Results

Conclusions
John Lloyd MEA582 Final Project
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script
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◦ Open Source
◦ Interpreted
◦ Contains GRASS APIs
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Written by Eric Hardin
◦ Graduate Research Assistant at NCSU
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Used to partition the shore along Outer Banks
Creates
◦ Lines/transects perpendicular to shore
◦ Or polygons along the shore
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Parameters
◦ Distance between transects
◦ Length of transects
John Lloyd MEA582 Final Project
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

Introduction
Environment Setup
◦ Linux
◦ Windows
◦ Running Python


v.transects.py
Testing
◦ Methodology
◦ Test Sets
◦ Results

Conclusions
John Lloyd MEA582 Final Project
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Start
Run Test
Cases in
Linux
Defects
found?
No
Run Test
Cases in
Windows
Yes
Defects
found?
Yes
Fix Defects
No
Finish
Yes
Layers
the
Same?
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No
Compare
Linux/Windows
Output Layers
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Parameter Verification Set
◦ Verifies detects and handles incorrect parameters
◦ 10 test cases
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Shoreline Dataset Verification Set
◦ Nags Head shoreline in NC State Plane
◦ 9 test cases
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Polylines of Various Shapes Set
◦ Polylines not representative of shorelines
◦ 12 test cases
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WGS84 Set
◦ Data in the WGS84 projection
◦ 3 test cases
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Parameter defects
◦ Before: ValueError: invalid literal for float():
◦ After: ERROR: Invalid transect_spacing value.
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xxx
Windows Compatibility Defects
◦ ValueError: close_fds is not supported on Windows platforms
◦ ERROR: Unable to open ASCII file
◦ Transects along network of lines failed in Windows but passed in Linux
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Logic defects
◦ Output layer always correct layer if produced
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50m Transects along Shore
Transects around circle
50m Polygons along Shore
Transects along in street network
(created in Linux only)
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Example 1. Changed Temporary File Creation System Call
####################################
# write transects
def writeTransects( transects, output ):
transects_str = ''
for transect in transects:
transects_str += '\n'.join( [ 'L 2\n'+' '.
join(map(str,end_points[0]))
+'\n'+' '.join(map(str,end_points[1]))+
'\n' for end_points in transect ] )
a = tempfile.NamedTemporaryFile()
a.write( transects_str )
a.seek(0)
grass.run_command('v.in.ascii', flags='n', input=a.name,
output=output, format='standard')
a.close()
####################################
# write transects
def writeTransects( transects, output ):
transects_str = ''
for transect in transects:
transects_str += '\n'.join( [ 'L 2\n'+' '.
join(map(str,end_points[0]))
+'\n'+' '.join(map(str,end_points[1]))+
'\n' for end_points in transect ] )
# JL Rewrote Temporary File Logic for Windows
_, temp_path = tempfile.mkstemp()
a = open(temp_path, 'w')
a.write( transects_str )
a.seek(0)
a.close()
grass.run_command('v.in.ascii', flags='n', input=temp_path,
output=output, format='standard')
Example 2. Added Additional Parameter Validation
transect_spacing = float(options['transect_spacing'])
# JL Handling Invalid transect_spacing parameter
try:
transect_spacing = float(options['transect_spacing'])
except:
grass.fatal(_("Invalid transect_spacing value."))
if transect_spacing == 0.0:
grass.fatal(_("Zero invalid transect_spacing value."))
John Lloyd MEA582 Final Project
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

Introduction
Environment Setup
◦ Linux
◦ Windows
◦ Running Python


v.transects.py
Testing
◦ Methodology
◦ Test Sets
◦ Results

Conclusions
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Setting up environment from GRASS source
◦ Problems encountered
 Linux - missing packages
 Windows - environment variables for python
◦ Advantages of build from source not realized
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v.transect.py
◦ Previous testing eliminated logic defects
◦ Special testing for Windows needed
◦ Now fit for multiple environment and applications
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