Tagged Questions

2
votes
2answers
63 views

Built a query for polygon Shapefile in R

I use the package maptools to read in Shapefiles in R. I would like to know if there is a function that can built up a query/subset to select only some Polygons based on a specific attribute in the ...
1
vote
4answers
165 views

Counting road intersections and blocks

I have a shp file that consists of the road system of Mexico City. I would like to count the number of road intersections (crossings) and blocks (which I would define as a segment starting from one ...
3
votes
2answers
79 views

How to cut a SHP based on another SHP using R

I have a Shapefile of points with certain information. I have another Shapefile with polygons corresponding to the states of the country I am working with (in this case Mexico). Since I only want to ...
2
votes
1answer
114 views

R: How can I create a polygon from several polygons and a line?

I have some spatial objects that I want to combine, namely three polygons and a line. The ultimate goal is to create a polygon that I can overlay on an area of a map of administrative divisions of the ...
1
vote
0answers
45 views

How to remove polygons in shapefile based on attributes in R [duplicate]

I have a shapefile where some attribute data is blank. I can delete those rows attribute table using na.omit. However, the polygons remain when I map the shapefile. I'm using R to make these changes. ...
7
votes
1answer
189 views

Removing rows in shapefile in R

I've imported a shapefile into R, and joined it to a table. My shapefile contains all the census ids, while my table only contains selected census ids. I'm now trying delete all the rows didn't get a ...
2
votes
0answers
150 views

How to Export a Shapefile as KML Using R

All, I have exported an ESRI shapefile (polygon) to KML using R, but the resulting layer shows only the outer extent of the polygon. How can I fill in the area with a color? Any help is greatly ...
10
votes
2answers
759 views

Using R to calculate the area of multiple polygons on a map that intersect with another overlaid polygon

I have a shapefile downloaded from the Ordnance Survey that gives electoral ward (division) boundaries for a county of the United Kingdom. I have successfully used R to load the shapefile and plotted ...
1
vote
3answers
228 views

Merge Zip Codes to Create new sales Markets

Let me preface this question by saying I am very novice with respect to GIS. With this in mind, I am looking to merge zip codes into sales territories. Instead of plotting data by zip code, I want to ...
3
votes
2answers
154 views

What is the cause of 'tearing' of polygons (artifacts) using R, ggplot and geom_polygon?

Thanks to the answer given in this question I have been able to subset and draw a map of electoral divisions in part of the UK, in this case Pembrokeshire. The resulting data frame is large and ...
5
votes
1answer
205 views

How can I use fortify() to create a filtered R data frame from a shape file?

I am in the process of building a ggplot choropleth map of population in administrative areas in Wales. I have downloaded the Boundary-Line data from the Ordnance Survey and extracted what seems to be ...
3
votes
1answer
135 views

How to stop writeOGR from abbreviating Field Names when using “ESRI Shapefile” driver

I'm currently using the following script to add some attribute data from a table to lots of individual shapefiles: library(rgdal) specieslist <- read.csv("SpeciesList1.txt", header=F) attdata ...
4
votes
2answers
564 views

How to draw a point at an exact location with spplot?

I imported a Shapefile holding a quite detailed world map from: http://www.diva-gis.org library(sp) library(rgdal) world = readOGR('./countries_shp/', 'countries') Using R with the sp-Packages, ...
6
votes
1answer
2k views

GIS, R and shapefiles

I have some data that encodes locations in certain countries, such as the US and China, that I would like to map. The data includes location name in Latin, extended Latin and other scripts (Japanese, ...
1
vote
1answer
804 views

merging 2 polygon adjacent to each other using R

I have several shp files which are the components (or tiles) of a map, I have joint all these tiles together to have a large shp file. Then I realized some of the polygon is now splitted into 2 ...
2
votes
2answers
139 views

Color a layer of the map based on the location of dots on another layer

Thanks for helping me in GIS 101 Problem #2, now I have followup questions: I created a map as below: The map is created using the following script: ct <- ...
4
votes
1answer
1k views

How to plot points on maps using ggplot2 and R?

Thanks for help me in GIS 101 Problem #1, now I have geocoded a few hospital in Connecticut using google map, I have able to visualize them in QGIS, now I am trying to do it in R. ct <- ...
1
vote
2answers
264 views

NA values in dbf when exporting shapefile from R with writeOGR?

I´m writing an esri shapefile from R (2.14.1) on windows, using writeOGR in the rgdal package, in the resulting dbf file, NA values in the spatialpointdataframe (in numeric columns) are not translated ...
13
votes
4answers
4k views

How to open a Shapefile in R?

I need to open a shape file from ArcMap in R to use it for further geostatical analysis. I've converted it into ASCII text file, but in R it is recognized as data.frame. Coordinates function doesn't ...
4
votes
1answer
1k views

Spatial distance join between polygon and points using R?

I'm figuring out how to do a Intersection (Spatial Join) between point and polygons from shapefiles. My idea is to get the closest points and those points that match completely inside the polygons. In ...
7
votes
1answer
1k views

Instantiating spatial polygon without using a shape file in R

So, the usual way we read a shapefile in R is via the maptools package, like this: sfdata <- readShapeSpatial("/path/to/my/shapefile.shp", proj4string=CRS("+proj=longlat")) However, I have a use ...
4
votes
1answer
2k views

Converting a polygon into a raster using R

I'm trying to convert a shapefile into a raster within R. My approach is to read in the raster as follows: library(rgdal) # Loads SP package by default demo <- readOGR('F:/data/', 'shapefile') # ...