RPyGeo Query -- probably easy
Hi Alex,
Thank you so much for the suggestion and apologies for taking so long to
test it. I think the quotes are still a problem. I do indeed write all
my code in R-WinEdt but must be doing something wrong. In Python your
suggested escaped quotes works fine but perhaps I missed something in
RPyGeo:
This code works in Python:
gp.makefeaturelayer("abc.shp", "walk")
gp.SelectLayerByAttribute('walk','NEW_SELECTION','\"hrwk05\" <> 0')
This code works in R:
rpygeo.geoprocessor(
"makefeaturelayer('abc.shp', 'walk')",
"SelectLayerByAttribute('walk','NEW_SELECTION','')",
env=myenv)
This code gives me an error in R:
rpygeo.geoprocessor(
"makefeaturelayer('abc.shp','walk')",
"SelectLayerByAttribute('walk','NEW_SELECTION','\"hrwk05\" <> 0')",
env=myenv)
File "x:\projects\rpygeo.py", line 10
gp.makefeaturelayer('abc.shp','walk')(
"SelectLayerByAttribute('walk','NEW_SELECTION','"hrwk05" <> 0')" )
^
SyntaxError: invalid syntax
NULL
(note from Zev -- the carrot occurs under the "05")
Alexander Brenning wrote:
Hi Zev,
the problems are definitely your quotes. First, they are syntactically
incorrect - I count seven double quotes (I recommend using some editor
with syntax highlighting, like Tinn-R or R-WinEdt, this helps discover
mismatches). Second, escaping them (\") should allow you to put double
quotes inside a double-quoted character string.
This might be closer to what you want to do (but I haven't tried to
run it - sorry, busy end of term...):
rpygeo.geoprocessor("makefeaturelayer('X:\\abc.shp','walk')",
"SelectLayerByAttribute('walk','NEW_SELECTION','\"hrwk05\"<>0')",
env=myenv)
Note that an additional argument clean.up=FALSE to the
rpygeo.geoprocessor allows you to inspect the Python file to check
whether the quotes are syntactically correct in Python.
I hope this helps
Alex
Zev Ross wrote:
Hi All,
I'm wondering if anybody could give me a little guidance on
formatting a query using RPyGeo. I'm excited to be able to run Python
geoprocessing functions straight from R but am having trouble with
the quote, double quote kinds of issues.
Here's an example of what I'd like to run
rpygeo.geoprocessor("makefeaturelayer('X:\\abc.shp',
'walk')", "SelectLayerByAttribute('walk','NEW_SELECTION', ' "hrwk05"
'<>0")",env=myenv)
Where the sticking point is hrwk05 <> 0. In Python my query would be
double quote, field name, close double quote, comparison, number e.g,
"hrwk05" <> 0 but I'm not sure how to put this into RPyGeo
If I run like so:
rpygeo.geoprocessor("makefeaturelayer('X:\\abc.shp',
'walk')", "SelectLayerByAttribute('walk','NEW_SELECTION',
'')",env=myenv)
it runs.
Thank you in advance for assistance.
Zev
Zev Ross ZevRoss Spatial Analysis 120 N Aurora, Suite 3A Ithaca, NY 14850 607-277-0004 (phone) 866-877-3690 (fax, toll-free) zev at zevross.com