[R] Coloring counties on a full US map based on a certain criterion

[Dimitri Liakhovitski]

Thank you somuch, Sarah. I tried, and it's working just wonderfully
(code below).
One last question, if I may: is it possible to get rid of borders
between counties (just leave the fill)? I did not find this argument
in help...
Thank you!
Dimitri

### My criterion for all counties.:
allcounties<-data.frame(county=map('county', plot=FALSE)$names)
allcounties$group<-c(rep(1:6,513),rep(1,4))[order(c(rep(1:6,513),rep(1,4)))]
### My colors:
classcolors <- rainbow(6)
map('county',fill=TRUE,col=classcolors[allcounties$group])
map('state', lwd=2, add=TRUE)



> Sure. Just start with
> map('county')
> instead.
> I like to add something like:
> map('state', lwd=3, add=TRUE)

I am trying:
### My criterion for all counties in the US:
allcounties<-data.frame(county=map('county', plot=FALSE)$names)
allcounties$group<-sample(1:5,3082,replace=TRUE)
### My colors:
classcolors <- rainbow(5)
### Trying to build the map - not working:
map(database='usa',regions='county',fill=TRUE,col=classcolors[allcounties$group])



> You'll need to instead coordinate with the names of the entire US:
>> length(map('county', plot=FALSE)$names)
> [1] 3082
>
> Sarah
>
>> Or maybe it's possible to create 48 colored state maps one by one -
>> the way you showed me - save them, and then somehow "paste" those
>> states onto the whole US map?
>> Thanks a lot for your help!
>> Dimitri
>>
>> On Fri, Jan 13, 2012 at 12:05 PM, Sarah Goslee <sarah.goslee at gmail.com> wrote:
>>> Hi,
>>>
>>> You've just about got it. See below.
>>>
>>> On Fri, Jan 13, 2012 at 11:52 AM, Dimitri Liakhovitski
>>> <dimitri.liakhovitski at gmail.com> wrote:
>>>> Dear Rers,
>>>>
>>>> is there a way to color counties on a full US map based on a criterion
>>>> one establishes (i.e., all counties I assign the same number should be
>>>> the same color)?
>>>> I explored a bit and looks like the package "maps" might be of help.
>>>> library(maps)
>>>> One could get a map of the US: map('usa')
>>>> One could get countries within a US state: map('county', 'iowa', fill
>>>> = TRUE, col = palette())
>>>
>>> Using a random sampling to give you the basic idea.
>>> There are 99 counties in Iowa, so to construct the criterion:
>>> countycol <- sample(1:5, 99, replace=TRUE)
>>> And to invent a set of colors (RColorBrewer is a better choice for
>>> final maps):
>>> classcolors <- rainbow(5)
>>>
>>> then you can use them in your map just as you would for any other
>>> plotting command:
>>>
>>> map('county', 'iowa', fill= TRUE, col = classcolors[countycol])
>>>
>>>> Would it be possible to read in a file with counties and their
>>>> assignments (some counties have a 1, some counties have a 2, etc.) and
>>>> then have one map of the US with counties colored based on their
>>>> assignment?
>>>
>>> Absolutely. The only thing you have to watch out for is that you put your
>>> values in the same order as:
>>> map('county', 'iowa', plot=FALSE)$names
>>>
>
>
> --
> Sarah Goslee
> http://www.functionaldiversity.org



-- 
Dimitri Liakhovitski
marketfusionanalytics.com