Ok, thanks. It's for about 100,000 points within thousands of polygons, and they need to 1) remain within a polygon and 2) retain original attribute data. Could be a challenging workflow... Paul
-----Original Message----- From: Baldwin, Jim -FS [mailto:jbald...@fs.fed.us] Sent: Saturday, January 28, 2017 1:22 AM To: Paul Lantos <paul.lan...@duke.edu>; r-sig-geo@r-project.org Subject: RE: jitter within polygon Point-in-polygon routines are pretty fast and straightforward to use. If it's about reducing computing time, then maybe for "irregular" polygons it would be easier to stratify the points into two groups: those points whose jittering would not go outside the polygon and those that might and only use point-in-polygon on the potentially outside points. However, I'd try the point-in-polygon route first and see if it is fast enough first. Jim -----Original Message----- From: Paul Lantos [mailto:paul.lan...@duke.edu] Sent: Friday, January 27, 2017 9:49 PM To: Baldwin, Jim -FS <jbald...@fs.fed.us>; r-sig-geo@r-project.org Subject: RE: jitter within polygon Thanks, Jim. There isn't a way to specify the polygons a priori in order to constrain the jittering? Paul -----Original Message----- From: Baldwin, Jim -FS [mailto:jbald...@fs.fed.us] Sent: Saturday, January 28, 2017 12:47 AM To: Paul Lantos <paul.lan...@duke.edu>; r-sig-geo@r-project.org Subject: RE: jitter within polygon Sounds like you need a "point-in-polygon" routine to determine if the jittered point is still within the polygon. R has several such routines. Here are two: pnt.in.poly in the SDMTools package point.in.polygon in the sp package Mathematica has several options, too. Jim -----Original Message----- From: R-sig-Geo [mailto:r-sig-geo-boun...@r-project.org] On Behalf Of Paul Lantos Sent: Friday, January 27, 2017 9:30 PM To: r-sig-geo@r-project.org Subject: [R-sig-Geo] jitter within polygon I am trying to figure out how to randomly jitter points within an overlying polygon structure. I can easily jitter the points themselves, but I would like this to be constrained by the boundaries of polygons containing the points. This isn't for visualization - I can do that easily enough in GIS. I actually need to generate coordinates. Thanks, Paul Paul M. Lantos, MD, MS GIS, FIDSA, FAAP, FACP Contact Departments of Internal Medicine and Pediatrics 919-684-6355 (Pediatric Infectious Diseases) Pediatric Infectious Diseases 919-681-8263 (Hospital Medicine) General Internal Medicine paul.lan...@duke.edu Duke University School of Medicine @PaulLantos Duke Global Health Institute [[alternative HTML version deleted]] _______________________________________________ R-sig-Geo mailing list R-sig-Geo@r-project.org https://urldefense.proofpoint.com/v2/url?u=https-3A__stat.ethz.ch_mailman_listinfo_r-2Dsig-2Dgeo&d=CwIFAg&c=imBPVzF25OnBgGmVOlcsiEgHoG1i6YHLR0Sj_gZ4adc&r=pCiIbVPBNWU0azo0D48ChUH_fawb-FalNVOf1sUn1r4&m=i4hWU9_Gy7AChLfLUddISsWbzbyNPkZ_ooonniSZoIY&s=ner0DbrTVNhQ2EgrDupUQkMsjZKVTOJHFF9CSyjUypU&e= This electronic message contains information generated by the USDA solely for the intended recipients. Any unauthorized interception of this message or the use or disclosure of the information it contains may violate the law and subject the violator to civil or criminal penalties. If you believe you have received this message in error, please notify the sender and delete the email immediately. _______________________________________________ R-sig-Geo mailing list R-sig-Geo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo
