Re: [R] plotting on a reverse log scale

From: Duncan Murdoch <murdoch_at_stats.uwo.ca>
Date: Thu 07 Jul 2005 - 07:22:38 EST

Michael Friendly wrote:
> Thanks Duncan,
> That is almost exactly what I want, except I want time to
> go in the normal order, not backwards, so:
>
> # plot on reverse log scale
> years1500 <- runif(500, 1500, 1990) # some fake data
> x <- -log(2000-years1500)
> from <- -log(2000-1990)
> to <- -log(2000-1500)
> plot(density(x, from=from, to=to), axes=F)
> rug(x)
>
> labels <- pretty(years1500)
> labels <- labels[labels<2000]
> axis(1, labels, at=-log(2000-labels))
>
> minorticks <- pretty(years1500, n=20)
> minorticks <- minorticks[minorticks<2000]
> axis(1, labels=FALSE, at=-log(2000-minorticks), tcl=-0.25)
>
> axis(2)
> box()
>
> -Michael
>
> Duncan Murdoch wrote:
>
>
>>On 7/6/2005 3:36 PM, Michael Friendly wrote:
>>
>>
>>>I'd like to do some plots of historical event data on a reverse log
>>>scale, started, say at the year 2000 and going
>>>backwards in time, with tick marks spaced according to
>>>log(2000-year). For example, see:
>>>
>>>http://euclid.psych.yorku.ca/SCS/Gallery/images/log-timeline.gif
>>>
>>>As an example, I'd like to create a density plot of such data with the
>>>horizontal axis reverse-logged,
>>>a transformation of this image:
>>>http://euclid.psych.yorku.ca/SCS/Gallery/milestone/Test/mileyears1.gif
>>>
>>>Some initial code to do a standard density plot looks like this:
>>>
>>>mileyears <- read.csv("mileyears3.csv", skip=1,
>>>col.names=c("key","year","where","add","junk"))
>>>mileyears <- mileyears[,2:4]
>>>
>>>years <- mileyears$year
>>>years1500 <- years[years>1500]
>>>dens <- density(years1500, from=1500, to=1990)
>>>plot(dens)
>>>rug(years1500)
>>>
>>>I could calculate log(2000-year), but I'm not sure how to do the
>>>plotting, do some minor tick marks
>>>and label the major ones, say at 100 year intervals.
>>
>>
>>I think you'll have to do everything explicitly. That is, something
>>like this:
>>
>>years1500 <- runif(500, 1500, 1990) # some fake data
>>x <- log(2000-years1500)
>>from <- log(2000-1990)
>>to <- log(2000-1500)
>>plot(density(x, from=from, to=to), axes=F)

Careful there: from > to, and that seems to have messed up density. Since the code assumes from < to, we should have a test and an error message (or a swap).

Duncan Murdoch

>>rug(x)
>>
>>labels <- pretty(years1500)
>>labels <- labels[labels<2000]
>>axis(1, labels, at=log(2000-labels))
>>
>>minorticks <- pretty(years1500, n=20)
>>minorticks <- minorticks[minorticks<2000]
>>axis(1, labels=FALSE, at=log(2000-minorticks), tcl=-0.25)
>>
>>axis(2)
>>box()
>>
>>Duncan Murdoch
>
>



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