How to Turn Gpclibpermit() to True

How to turn gpclibPermit() to TRUE

I've struggled with the gpclibPermit issue myself. You don't provide a reproducible example, but I am guessing that you are having a sesion like this:

library(maptools)
Checking rgeos availability: FALSE
Note: when rgeos is not available, polygon geometry computations in maptools depend 
    on gpclib, which has a restricted licence. It is disabled by default;
to enable gpclib, type gpclibPermit()
> gpclibPermitStatus()
[1] FALSE
> gpclibPermit()
[1] FALSE
> gpclibPermitStatus()
[1] FALSE

At this point it helps to look at what gpclibPermit and gpclibPermitStatus actually do:

> gpclibPermit
function ()  
{
if ("gpclib" %in% .packages(all.available = TRUE)) 
    assign("gpclib", TRUE, envir = .MAPTOOLS_CACHE)
if (gpclibPermitStatus()) 
    warning("support for gpclib will be withdrawn from maptools at the next major release")
gpclibPermitStatus()
}
<environment: namespace:maptools>
> gpclibPermitStatus
function () 
    get("gpclib", envir = .MAPTOOLS_CACHE)
<environment: namespace:maptools>

That is, you can't give maptools the permission to use gpclib unless you have the package gpclib installed.

install.packages("gpclib")
library(maptools)
Loading required package: sp
Checking rgeos availability: FALSE
Note: when rgeos is not available, polygon geometry computations in maptools depend on gpclib,  which has a restricted licence. It is disabled by default; to enable gpclib, type gpclibPermit()

> gpclibPermit()
[1] TRUE
Warning message:
In gpclibPermit() :
support for gpclib will be withdrawn from maptools at the next major release
> gpclibPermitStatus()
[1] TRUE

Error: isTRUE(gpclibPermitStatus()) is not TRUE

You can look at Hadley's master file for ggplot2/R/fortify-spatial.r. Based on this outside link, my understanding is that lines 31–34 (in it's current form) used to read something like

# Union together all polygons that make up a region
try_require(c("gpclib", "maptools"))
unioned <- unionSpatialPolygons(cp, invert(polys))

So back then one way to attack the problem was to turn on the license

library(rgdal)
library(maptools)
if (!require(gpclib)) install.packages("gpclib", type="source")
gpclibPermit()

As @rcs, @Edzer Pebesma, and this answer mention, rgeos should resolve the issue for more recent installations.

gpclibPermit() is FALSE, cannot install gpclib

"Extract[ing] to library folder" is not the correct way to install a source package (the .tar.gz you downloaded). Inside R execute

install.packages(path_to_file, repos = NULL, type="source")

More details and approaches can be found at How do I install an R package from source?

Converting spatial polygon to regular data frame without use of gpclib tools

You need to also install the rgeos package. When maptools is loaded and rgeos is not installed, the following message is shown:

> require("maptools")
Loading required package: maptools
Checking rgeos availability: FALSE
    Note: when rgeos is not available, polygon geometry
    computations in maptools depend on gpclib,
    which has a restricted licence. It is disabled by default;
    to enable gpclib, type gpclibPermit()

When fortify is called with a region argument (as it is in the example you linked to), then some "polygon geometry computations" need to be done. If rgeos is not available, and gpclib is not permitted, it will fail.

tract_choropleth for NY data

The error is due to gpclibPermitStatus() returning FALSE.

Unfortunately, this is a common error that comes up when working with choroplethr. I once gave a lengthy answer to the question here.

The short answer is to type the following:

install.packages("gpclib")
library(maptools)
gpclibPermit()

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