[R] plot control

2006-04-24 Thread Alexander Nervedi
Dear R gurus,

I'd like to plot a distribution with the tickmarks always at the quantiles 
of the y-axis, as opposed to the quantiles of the distribution I am 
plotting. plot seems to place these ticks based on some calculations that I 
cant see (?plot doesnt show the innards of plot).

Below is some functional code, but the tick marks are placed unattractively 
since I am referencing the quantiles of the distribution. I'd ideally like 
the tickmarks to be able to reference fixed points on the y-axis and the 
show the associted values.

I'd be very grateful for ideas, suggestion and leads.

- alex.

# some code

y1-rnorm(100)
y2-runif(100)
x -1:100

l -length(y1)
mat-scale(cbind(y1,y2))

plot(x, mat[,1], col = blue, yaxt = n, ylab=)
axis(2, at = sort(mat[,1])[c(0.25*l,0.5*l,0.75*l)],
labels = round(sort(y1)[c(0.25*l, 0.5*l,0.75*l)],2))

points(x, mat[,2], col = red)
axis(4, at = sort(mat[,2])[c(0.25*l,0.4*l,0.75*l)],
labels = round(sort(y2)[c(0.25*l, 0.5*l,0.75*l)],2))

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Re: [R] plot control

2006-04-24 Thread Michael Dondrup
Hi,
it's not quite clear to me, what you are trying to accomplish with this. You 
are referring to quantiles (you means quartiles in your case?, 
see ?quantile ). So, are you trying to compare theoretical quantiles of a 
distribution to the empirical quantiles?  Or are you just trying to split the 
left axes into 4 ticks? For the first case, try something like:
 y - rnorm(100)
  y.right.axisticks - quantile(y)
  y.left.ticks - qnorm(c(0.25,0.5,0.75)) #makes no sense to compare with 
  # theor. quantiles of uniform distribution, right?  ;) 
  plot(y,yaxt='n')
 axis(2,at=y.left.ticks,labels=round(y.left.ticks,3))
 axis(4,at=y.right.axisticks,labels=round(y.right.axisticks,3))
or for the latter:
  yrange - range(y)
  y.left.ticks - seq(yrange[1], yrange[2], (yrange[2] - yrange[1])/4)
  plot(y,yaxt='n')
 axis(2,at=y.left.ticks,labels=round(y.left.ticks,3))
 axis(4,at=y.right.axisticks,labels=round(y.right.axisticks,3))
is that, what you thought of?
see also:
?qqplot
for another way to compare quantiles

cheers


Am Monday 24 April 2006 08:53 schrieb Alexander Nervedi:
 Dear R gurus,

 I'd like to plot a distribution with the tickmarks always at the quantiles
 of the y-axis, as opposed to the quantiles of the distribution I am
 plotting. plot seems to place these ticks based on some calculations that I
 cant see (?plot doesnt show the innards of plot).

 Below is some functional code, but the tick marks are placed unattractively
 since I am referencing the quantiles of the distribution. I'd ideally like
 the tickmarks to be able to reference fixed points on the y-axis and the
 show the associted values.

 I'd be very grateful for ideas, suggestion and leads.

 - alex.

 # some code

 y1-rnorm(100)
 y2-runif(100)
 x -1:100

 l -length(y1)
 mat-scale(cbind(y1,y2))

 plot(x, mat[,1], col = blue, yaxt = n, ylab=)
 axis(2, at = sort(mat[,1])[c(0.25*l,0.5*l,0.75*l)],
 labels = round(sort(y1)[c(0.25*l, 0.5*l,0.75*l)],2))

 points(x, mat[,2], col = red)
 axis(4, at = sort(mat[,2])[c(0.25*l,0.4*l,0.75*l)],
 labels = round(sort(y2)[c(0.25*l, 0.5*l,0.75*l)],2))

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 R-help@stat.math.ethz.ch mailing list
 https://stat.ethz.ch/mailman/listinfo/r-help
 PLEASE do read the posting guide!
 http://www.R-project.org/posting-guide.html

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R-help@stat.math.ethz.ch mailing list
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PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html