5,960 reputation
11431
bio website geonet.esri.com/blogs/…
location Ottawa, Canada
age 61
visits member for 4 years, 8 months
seen 3 hours ago

Instructor Geomatics, Carleton University ON Canada


Apr
10
answered Syntax error running script in PythonWin after success in ArcPy
Apr
7
comment Correlation analysis of two polygon shapefiles with nominal data
In my discipline it is usually used as a test for independence (association) rather than its use associated with distributions (Fisher's I think).
Apr
7
comment Correlation analysis of two polygon shapefiles with nominal data
I am sure you are aware that Chi-square can be applied in more scenarios than that...the Kappa portion is for obs-exp in the strictest sense of the word. A quick perusal of the definition of 'expected' as it relates to chi-square will indicate that the use there-in is correct. One should always state a null hypothesis for Chi as being either a test of association or difference, depending upon one's discipline...not a test of correlation, which is unfortunately used by generalists.
Apr
7
answered Correlation analysis of two polygon shapefiles with nominal data
Apr
7
comment Interpolation and classification of soil texture data
@ChrisW as in the point I was making...no interpolation , allocate soil classes using Voronoi Diagrams or Delauney triangulation instead. That is how soils are classes from field observations of landscapes and the results lab and/or field tests of particle size distribution. Producing a soil class from %sand, %silt and %clay can be partially automated using ternary diagrams to produce the classes 'automagically' then these classes can be assigned to the point locations for allocation. There are examples on the web to do this using USDA soil textural triangles...I used them in the 80's
Apr
5
reviewed Approve Converting .ecw to .jp2
Apr
4
comment Interpolation and classification of soil texture data
@ChrisW whuber made correct statements in that link. The originator of that post said it most eloquently in a comment "Yikes! I just KNEW this was going to be more complicated than just slapping a function on the data!" I can only add...just because something can be done doesn't mean it should be....perhaps tarnished by my involvement in both statistics and soils courses.
Apr
4
comment Interpolation and classification of soil texture data
Hold it... could someone flag @whuber about this idea. upscaling data which have already been classed is not the way to go. even if you have %sand %silt and %clay, you cannot interpolate each of those layers, singly or together to produce a "soil class" Why? Because that is not how soils are developed. They are due to lithological, depositional and a variety of conditions. The best you can do is to ascribe your soil class to particular areas treating each of your sampling points as locations and using spatial allocation methods to say "this point likely represents this area" grief!
Mar
18
answered arcpy handling of floating points
Mar
18
comment arcpy handling of floating points
Use a spatial reference object, which I think pointgeometry supports, check the help. If a defined coordinate system is not used single precision is used in the calculations. References to this phenomenon are documented on this site and on geonet and a comment isn't the place to put them. No SR... = ... inaccurate results
Mar
15
comment ArcPy QueryPointAndDistance: Incorrect Lengths?
If a spatial reference isn't specified, you will get geometry errors. here is one example geonet.esri.com/thread/10256 You can specify it within the searchcursor as indicated in the help resources.arcgis.com/en/help/main/10.2/index.html#//…
Mar
1
comment Does GPS correct for continental drift?
I'm voting to close this question as off-topic because the person hasn't given the concept of continental drift and GPS precision and accuracy
Mar
1
comment Does GPS correct for continental drift?
how accurate is your GPS? :)
Feb
22
reviewed Approve How can I find GPS coordinates of the geographic center of US counties?
Feb
21
comment Exporting feature class into multiple feature classes based on field values using ArcGIS for Desktop?
yes the link is currently broken because ArcScripts 2.0 is being configured, It has been so long that I can't remember is it works on standalone tables, email if you want me to send you a copy. I am moving a lot of stuff over to NumPy and will have a new incarnation when ASv2 eventially appears
Jan
31
reviewed Approve Converting polyline data to polygons?
Jan
30
revised Difference between raster subsets as defined by another raster
clarification
Jan
30
comment Difference between raster subsets as defined by another raster
meant to post comment in the wrong section...too late to fix...in short...there is no correlation between nominal data, there may be an association...there is a difference, ask @whuber for commentary as to the distinctions
Jan
30
answered Difference between raster subsets as defined by another raster
Jan
28
comment Programmatically adding .shp file to .mxd file
try... arcpy.env.workspace = "C:/test/" ...with the extra / ... my example was just a sample...and obviously you dont have my data, so you will have to change them to reference your data...I was demonstrating what could be done. in that example, i had shapefiles stored in a folder relative to mxd_src which were used in the blank template mxd, from there symbology was applied using the lyr files and the mxd saved then ... with any luck arcmap was started with everything 'automagically' there