[R] Color US counties on US map using a numeric variable for color intensity

[Jim Lemon]

Hi Dimitri,
You can also try the color.scale function in plotrix, which allows you to
specify the NA color in the call.

newcol<-color.scale(mydata.final$Mean.Wait,extremes=c("yellow","red"),na.color="white")

Jim


On Fri, Apr 3, 2015 at 8:08 AM, Dimitri Liakhovitski <
dimitri.liakhovitski at gmail.com> wrote:

> Jean, I think I fixed it:
>
> newpal <- colorRamp(c("yellow", "red"))
> missing <- is.na(mydata.final$Mean.Wait)
> newcol <- ifelse(missing, "white",
>
> rgb(newpal(mydata.final$Mean.Wait[!is.na(mydata.final$Mean.Wait)]/
>                                   max(mydata.final$Mean.Wait,
> na.rm=T)), maxColorValue=255))
> map('county', fill=TRUE, col=newcol,
>     resolution=0, lty=0, bg="transparent")
> map('state', lwd=1, add=TRUE)
>
> One understanding question: what exactly does this rgb line do and why
> do we have to say "maxColorValue=255"?
> Thank you!
>
> On Thu, Apr 2, 2015 at 5:02 PM, Dimitri Liakhovitski
> <dimitri.liakhovitski at gmail.com> wrote:
> > Thank you, Jean, but I think this newcol line is not working. I am
> running:
> >
> > newcol <- ifelse(missing, "white",
> >
> > rgb(newpal(mydata.final$Mean.Wait/max(mydata.final$Mean.Wait,
> > na.rm=T)),
> >                      maxColorValue=255))
> >
> > # And I am getting:
> > Error in rgb(newpal(mydata.final$Mean.Wait/max(mydata.final$Mean.Wait,  :
> >   color intensity NA, not in 0:255
> >
> > I think it's not liking the NAs - despite the ifelse...
> >
> > On Thu, Apr 2, 2015 at 4:26 PM, Adams, Jean <jvadams at usgs.gov> wrote:
> >> Dimitri,
> >>
> >> You could use colorRamp() and rgb() to get more continuous colors.
> >> For example
> >>
> >> newpal <- colorRamp(c("yellow", "red"))
> >> missing <- is.na(mydata.final$Mean.Wait)
> >> newcol <- ifelse(missing, "white",
> >>   rgb(newpal(mydat$Mean.Wait/max(mydat$Mean.Wait)), maxColorValue=255))
> >> map('county', fill=TRUE, col=newcol,
> >>             resolution=0, lty=0, bg="transparent")
> >> map('state', lwd=1, add=TRUE)
> >>
> >> Jean
> >>
> >>
> >> On Thu, Apr 2, 2015 at 12:03 PM, Dimitri Liakhovitski
> >> <dimitri.liakhovitski at gmail.com> wrote:
> >>>
> >>> I have a data frame 'mydata.final' (see below) that contains US
> >>> counties and a continuous numeric variable 'Mean.Wait' that ranges
> >>> from zero to 10 or so. I also created variable 'wait' that is based on
> >>> the 'Mean.Wait' and takes on discrete values from 1 (lowest values on
> >>> 'Mean.Wait') to 5 (highest values on 'Mean.Wait').
> >>>
> >>> I can create a map of the US with the counties colored based on the
> >>> values of 'wait' using R package 'maps':
> >>>
> >>> #################################################################
> >>> ### Generating an artificial data file:
> >>> #################################################################
> >>> library(maps)
> >>> mydata.final <- data.frame(county = (map('county', plot =
> FALSE)$names),
> >>>                  stringsAsFactors = F)
> >>>
> >>> ### My numeric variable:
> >>> set.seed(123)
> >>> mydata.final$Mean.Wait <- runif(nrow(mydata.final)) * 10
> >>>
> >>> ### Introducing NAs to mimic my real data set:
> >>> set.seed(1234)
> >>> mydata.final$Mean.Wait[sample(1:nrow(mydata.final), 1500)] <- NA
> >>>
> >>> ### Cutting the original numeric variable into categories
> >>> ### because I don't know how to color based on 'Mean.Wait':
> >>> mydata.final$wait <- cut(mydata.final$Mean.Wait, breaks = 5)
> >>> levels(mydata.final$wait) <- 1:5
> >>> mydata.final$wait <- as.numeric(as.character(mydata.final$wait))
> >>>
> >>> ####################################################################
> >>> Building a US map based on 'wait' (5 categories)
> >>> #################################################################
> >>>
> >>> ### Creating my 5 colors:
> >>> pal <- colorRampPalette(c("yellow", "red"))
> >>> allcolors <- pal(5)
> >>>
> >>> ### Looking at my 5 colors:
> >>> barplot(1:5, rep(1,5), col = allcolors, horiz = T)
> >>>
> >>> ### Builiding the US map using 5 categories in 'wait':
> >>> map('county', fill = TRUE, col = allcolors[mydata.final$wait],
> >>>             resolution = 0, lty = 0, bg = "transparent")
> >>> map('state', lwd=1, add=TRUE)
> >>>
> >>> My goal is: instead of splitting 'Mean.Wait' into 5 ordered categories
> >>> ('wait'), I'd like to color the counties on the map based on the
> >>> intensity of my (continuous) 'Mean.Wait'. What would be the way to do
> >>> it and maybe even to add a legend?
> >>> Thanks a lot!
> >>>
> >>> --
> >>> Dimitri Liakhovitski
> >>>
> >>> ______________________________________________
> >>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> >>> https://stat.ethz.ch/mailman/listinfo/r-help
> >>> PLEASE do read the posting guide
> >>> http://www.R-project.org/posting-guide.html
> >>> and provide commented, minimal, self-contained, reproducible code.
> >>
> >>
> >
> >
> >
> > --
> > Dimitri Liakhovitski
>
>
>
> --
> Dimitri Liakhovitski
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

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