similar to: help with using grid.polygon()

I have a complex 2D polygon with thousands of vertices, and I'd like to be able to identify points from a large set contained within the polygon, and was wondering if there might be an efficient way of doing this? Any advice would be useful! Here is a small example of what I mean: # make polygon v1<-c(0,1,1,2,1,3,6,7) v2<-c(1,3,3,5,6,7,8,9) plot(v1, v2, type = "n" )

Objective: Determine if a set of x and y-latitude points are inside of a polygon using R. Lets say I have 9 polygons. Where I have labeled the polygons to be checked from 1-9. The problem I?m running into is running the point.in.polygon to check if those points are in one of several polygons, as my code overwrites the result. To accomplish this I am using the R-built in function called

Hi, I wonder whether there is a way to generate a polygon (a triangle in my case) with color gradient using grid.polygon() in package grid? I tried something like library(grid) grid.polygon(x=c(0, 0.5, 1), y=c(0.5, 1, 0.5), gp=gpar(col=NA, fill=colorRampPalette(c("green", "lightgray"), space="Lab")(200))) But am only

The angle is not based on the polygon edges, but it can seem that way if you do not use the asp=1 argument in your plot. Try this example, > plot(1:10, 1:10, type='n') > x <- c(1, 3, 5, 3) > y <- c(3, 5, 3, 1) > polygon(x, y, angle=0, density=10) > polygon(x, y + 4.5, angle=45, density=10) > polygon(x + 4.5, y + 4.5, angle=90, density=10) > polygon(x + 4.5, y,

Filling polygons with lines is a throwback to the time when the height of quality graphics was the mechanical pen plotter (a device that used a pen in a mechanical arm to draw the plot on a piece of paper). Computing and printing technology has advanced quite a bit from that day, so you may want to reconsider why you want polygons filled with lines instead of just a solid color (and I consider

Hello dear members of R-help and R-core mailing list, I am not sure if this request is a "ticket" that should be filled somewhere outside the mailing list. If so, I apologize for not doing and would like to know where I should have filled it. And to the subject matter: I would like to use a command like this: plot(c(1,8), 1:2, type="n") polygon(1:7, c(2,1,2,NA,2,1,2),

Hello dear members of R-help and R-core mailing list, I am not sure if this request is a "ticket" that should be filled somewhere outside the mailing list. If so, I apologize for not doing and would like to know where I should have filled it. And to the subject matter: I would like to use a command like this: plot(c(1,8), 1:2, type="n") polygon(1:7, c(2,1,2,NA,2,1,2),

Tena koe Simon plot(1:10, 1:10, type='n') polygon(c(2,3,6,8), c(2,5,5,3), density=20, angle=90) polygon(c(2,3,6,8), 5+c(2,5,5,3), density=20, angle=0) I don't understand your problem. Perhaps if you "provide[d] commented, minimal, self-contained, reproducible code" it would help. HTH .... Peter Alspach -----Original Message----- From: R-help [mailto:r-help-bounces at

Am just feeling my way into the grid library, and cannot figure out how to define the plot limits. 3/5 of the example polygons below plot in the default 0-1 range viewport. But when I try to redefine the viewport the polygons plot in the same places. I also get the same result without employing push/pop. (As you can see from the scale I'm trying to introduce, I want to plot map polygons.)

Hello: I would like to superimpose vector polygons (state outlines) from a Shape file on top of a satellite image, imported into a SpatialGridDataFrame from GEOTIFF via gdal_translate and readGDAL. When I plot polygon and point shape files in R, into SpatialPointDataFrame and SpatialPolygonDataFrame, the two feature sets line up geographically, so it seems logical that a SpatialGridDataFrame

I am trying to use the angle option in polygon to create polygons filled with horizontal and vertical lines. The polygons I am crating are irregular and it the angle function appears to set the angle of the shading perpendicular to the polygon sides rather than perpendicular to the axes. Is there any way to set the angle relative to the axes rather than relative to the polygon sides?

Thanks for the question. Here is a sample of the code for my plot: Top = c(34, 39, 42, 45, 46, 41, 41, 40, 43, 38, 33, 33) Bottom = c(24, 29, 32, 36, 32, 34, 32,41, 40, 39, 29, 24) plot(1,1, col = "white", xlim = c(1.3,11.7), ylim = c(0,80), axis = FALSE, xaxt = "n") axis(1, at = c(1:12)) polygon(c(c(1:12),c(12:1)), c(top, bottom), col =

I have a list of bounds for a series of polygons. I do understand the formula to determine whether point i is within polygon X (X[x1] < i[x] & X[x2] > i[x] & X[y1] < i[y] & X[y2] > i[y]), and I can apply this throughout the dataset. However, this naive algorithm doesn't scale very well. The data set contains 10,000 points consisting of (n,e) pairs where I'm

Hello, I need to calculate the centroids of some spatial polygons that I have placed into a Polygons-class object. Is the labeling point in the Polygons-class the centroid of the polygon? Thank you for your help.

I am a new user of the R spatstat package and am having problems creating a polygonal observation window with owin(). Code follows: library("maps") library ("sp")` library("spatstat") mass.map <- map("state", "massachusetts:main", fill=T) # This returns a data frame includding x and y components that form a polygon of massachusetts mainland`

Dear R users, I'm trying to extract from a given matrix (GROUP) the coordinates of the vertices of the different groups (i.e. 3, 7, 1 . . .) to plot the polygons to delineate the area in which each group "wins" and colour it diferentially. I can make a simple point plot, but I would like to add polygons with full colored area. The example is with a 5x5 matrix, but I'm working

Hi, Is there a simple way to suppress the plotting of polygon boundaries with spplot() ? # simple list of 12 colors cols <- brewer.pal(12, "Paired") # plot pile of polygons, with 12 classes: spplot(x, zcol='class2', col.regions=cols, scales=list(draw=T), xlab="Easting (m)", ylab="Northing (m)") ... seems to work well. However the polygon boundaries

Greetings! I'm using the extract command (raster package) with a raster layer (x) and a spatial polygons dataframe (y). I'm using it to extract the sum of raster values by each spatial polygon. However, I'm getting NAs as a result for some polygon IDs, which I know isn't true because that doesn't happen in ArcGIS. Does anyone experienced the same issue? Thanks! Joao

Dear R-helpers, thanks for yesterday's speeding-up tip. Here is my next query: I have lots of polygons (not necessarily convex ones, and they never have holes) given by x,y coordinates. I want to get the polygon that is the union of these polygons. This is my current method, but I am hoping there is a faster method (up to thousands of polygons, each with ca. 40 xy points). Example:

Dear all In order to clearly mark values wich are larger than a treshold value, I would like to color the surface below the line given by plot (yy~xx). To color is only the surface between abline (treshold) and yy if they are larger than the specific limit. I guess I can use the function polygon, but I can not find any valuable solution. I'm grateful to you for an advice or an example.