[R] Dot plot - equivalent of MINITAB

[Greg Snow]

Does the 'dots' function in the TeachingDemos package do what you want? (It fits one interpretation of your description, but my minitab is a bit rusty, so not sure).

(The "you" above referring to kerfuffle, not Rolf, for some reason I received the reply, but not the original).

--
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
801.408.8111


> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Rolf Turner
> Sent: Thursday, September 25, 2008 2:57 PM
> To: kerfuffle
> Cc: r-help at r-project.org
> Subject: Re: [R] Dot plot - equivalent of MINITAB
>
>
> On 26/09/2008, at 7:51 AM, kerfuffle wrote:
>
> >
> > hi folks,
> >
> > Bit of a newbie, but I've spent a fair bit of time looking for an
> > answer on
> > this, with no joy.  Can anyone help me?
> >
> > Dataset: A single column of values in a csv file (eg. 52, 53, 54,
> > 85, etc)
> >
> > Goal: In Minitab, you have what they call a dot plot.  It's a
> > histogram,
> > where a single dot represents a set of identical values (eg. 57,
> > 57, 57
> > would be one dot).   Multiple dots are stacked on top of each other
> > (as if
> > gravity was affecting them). The advantage is that outliers are
> > very visible
> > (since a single 155 still gets a single dot).  The net effect is a
> > rug plot,
> > but in the main portion of the plot, not just on the axis.
> >
> > Tried: I've played with dotchart and dotchart2 with no joy (eg.
> > dotchart(nc$bac) (where nc is the dataset and bac is the column
> > header).
> > They do provide multiple dots (so that ten values of 57 are given 3
> > dots)
> > but these overlap and aren't arranged in a logical way.  Sometimes
> > a single
> > dot has a large y-value, sometimes it isn't.  As a result of this
> > non-gravitational effect, it doesn't look like a histogram at all.
> > It's
> > also strange that the background of the plot is stripy.  This
> > implies I'm
> > doing something very wrong, but don't know what.  I had a look at
> > the plot
> > galleries, and didn't see anything else that looked like what I
> wanted
> > (except the rug plots).
>
> Here's something that will do at least roughly what you want.  The
> fundamentals of this function were written for me by Barry Rowlingson.
> (Thanks Baz!)
>
> dotplot.mtb <- function (x, xlim = NULL, main = NULL, xlab = NULL,
> pch = 19,
>      hist = FALSE, yaxis = FALSE)
> {
>      if (is.null(xlim))
>          xlim <- range(pretty(range(x)))
>      if (is.null(main))
>          main <- ""
>      if (is.null(xlab))
>          xlab <- ""
>      x <- sort(x)
>      w <- table(x)
>      mw <- max(w)
>      w <- unlist(lapply(w, function(n) {
>          1:n
>      }))
>      Nmax <- floor(par()$pin[2]/strheight("o", units = "inches"))
>      if (mw <= Nmax & !hist) {
>          plot(range(x, na.rm = TRUE), c(0, 1), type = "n", xlab = "",
>              ylab = "", xlim = xlim, main = main, axes = FALSE)
>          par(usr = c(par()$usr[1:2], -Nmax/2, Nmax/2))
>          y <- strheight("o") * w
>          points(x, y, pch = pch)
>          axis(side = 1, pos = 0)
>          if (yaxis) {
>              a <- 0
>              b <- round(Nmax/10)
>              at <- seq(a, by = b, length = 10)
>              axis(side = 2, at = at)
>          }
>      }
>      else {
>          if (hist)
>              plot(x, w, type = "h", xlab = "", ylab = "", xlim = xlim,
>                  ylim = c(-mw - 1, mw + 1), main = main, axes = FALSE)
>          else plot(x, w, pch = pch, xlab = "", ylab = "", xlim = xlim,
>              ylim = c(-mw - 1, mw + 1), main = main, axes = FALSE)
>          axis(side = 1, pos = -0.02 * mw)
>          if (yaxis) {
>              a <- 0
>              b <- max(1, round(mw/10))
>              at <- seq(a, by = b, length = 10)
>              axis(side = 2, at = at)
>          }
>      }
> }
>
>
>         cheers,
>
>                 Rolf Turner
>
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