4,480 reputation
1122
bio website barry.rowlingson.com
location Lancaster, United Kingdom
age 49
visits member for 4 years, 9 months
seen yesterday

Here I am.


Jun
22
comment How to choose a shapefile interactively in R
I always forget that one. Why did you put so much useful vector stuff in the raster package!!??
Jun
22
comment Why does R(gdal) mangle data when converting to geojson?
"fails" how? After manually adding a "crs" (for epsg:27700) to the geoJSON, I see mostly grey but a few white polygons. Are the white ones the problem? I suspect they go anticlockwise instead of clockwise or something... plot() with a fill seems to work, so maybe qtm isn't behaving...
Jun
22
comment Why does R(gdal) mangle data when converting to geojson?
My rgdal flat out errors in reading that geojson with Error in validityMethod(as(object, superClass)) : Geographical CRS given to non-conformant data: 655604.700 657534.101. Its not WGS84...
Jun
20
revised Processing large amounts of Rasters in R
plain R not RStudio here
Jun
20
revised I need to create a function in R that processes rasters in esri grid format
plain R not RStudio here
Jun
20
answered How to choose a shapefile interactively in R
Jun
17
comment GlobCover 2009 dataset - importing legend and colormap values into R
The colortable stuff in package:raster is poorly documented, there's not even any real functions for it which is why you end up setting the colours explicitly with @-stuff. Maybe I'll write some helper functions and see if Rob H wants to put them in the package...
Jun
16
revised GlobCover 2009 dataset - importing legend and colormap values into R
added 24 characters in body
Jun
16
answered GlobCover 2009 dataset - importing legend and colormap values into R
Jun
8
comment Use GRASS through R
Show us what you tried, and where you got stuck, and then we can try and get you past that. Have you installed rgrass7?
Jun
1
comment QGIS / Python differences in result
To be sure, you should test it on something where you know the result. Construct a small raster with known values where you can hand-compute the result you want. Then test. For all you know, your QGIS and python calculations could both be wrong!
May
30
comment How to split a road network into parts of same length?
I think this is a k-Chinese Postman Problem: wiso.tu-dortmund.de/wiso/or/Medienpool/publikationen/… where you want to minimise the maximum cost of any single postman...
May
29
comment How to split a road network into parts of same length?
Optimally splitting the network is hard. Imagine a block-design city. If you split down the middle of a block, you end up with lots of dead-end arcs that will get traversed twice. The better solution is to split across four-way intersections to create edges that look like brickwork. Hard to explain in words! The edge problem might only be significant if your areas are going to be mostly edges. Hmm this is a fun problem...
May
29
comment How to split a road network into parts of same length?
There's an old-looking QGIS plugin which probably doesn't work with the latest QGIS: github.com/rkistner/chinese-postman but it might give you some code and ideas to use!
May
29
comment How to split a road network into parts of same length?
Sounds more like a Route Inspection ("Chinese Postman") Problem (en.wikipedia.org/wiki/Route_inspection_problem) complicated by having four post-deliverers.
May
29
comment How to split a road network into parts of same length?
I don't suppose its a nice regular gridded city is it?
May
6
comment Creating 3D terrain/model from contour lines, preferably using Open Source GIS?
Then you've got no chance. You don't know if a line is 7m higher or 7m lower than its neighbour? How do you think you can reconstruct the elevation? Unless you have a very simple slope. Any chance of seeing this?
May
5
comment Temporal correlation of point data
Tricky, since water leaks are probably more likely where there are more pipes, and that's where there are more people, and that's where you get more diseases. So you may see a correlation purely because pipes are where all the people are. Do you have an at-risk population dataset? And a map of the pipes? Although this probably isn't as important in a purely temporal analysis if the population doesn't change much...
May
5
comment Creating 3D terrain/model from contour lines, preferably using Open Source GIS?
Never mind the 2m/7m distinction, how do you know the height of each contour line?
Apr
26
comment Writing out comma separated values inside a single cell in a spreadsheet using python
There's not a lot of GIS in this, try stackoverflow.com