# [R] Telling plot() the max y value to expect when plotting one distribution and then using lines() to add more distributions

R. Michael Weylandt michael.weylandt at gmail.com
Sun Feb 26 01:45:28 CET 2012

```I had never actually played with matplot before -- thanks for the great tip.

Michael

On Sat, Feb 25, 2012 at 7:39 PM, Peter Ehlers <ehlers at ucalgary.ca> wrote:
> See inline below.
>
> On 2012-02-25 12:40, R. Michael Weylandt wrote:
>>
>> I might (re-)format your code as follows -- others will make some
>> different design decisions. This isn't the most efficient (more
>> vectorization could be squeezed in there and it's arguably better to
>> use apply statements but I'd argue you'd loose clarity here) but I
>> think it shows some useful R idioms that are helpful for someone who
>> (to use Patrick Burns' phrase) "speaks R with a C accent."
>> (Incidentally, look up a text called "the R inferno": all sorts of
>> goodies in there)
>>
>> library(PearsonDS)
>>
>> PARAMETERS = data.frame(color = c("red", "blue", "green"), label =
>> c(1, 2, 3), m = c(1.95, 18.35, 1.93), nu = c(0.08, -1.02, 0.25),
>> location = c(0.0048,  -0.00254, 0.00189), scale = c(0.0115, 0.082187,
>> 0.026675), stringsAsFactors = FALSE)
>>
>> x<- seq(-0.06, 0.06, length = 100)
>>
>> densities<- matrix(NA, nrow = nrow(PARAMETERS), ncol = length(x))
>> for(i in seq_len(nrow(PARAMETERS))){
>>   densities[i, ]<- with(PARAMETERS[i, ], dpearsonIV(x, m, nu, location,
>> scale))
>> }
>>
>> plot(x, rep(0, length(x)), ylim = c(0, max(densities)), xlab = "x
>> value", ylab = "Density", main = "SPX", type = "n")
>> for(i in seq_len(nrow(PARAMETERS))){
>>   lines(x, densities[i, ], col = PARAMETERS[i, "color"])
>> }
>
>
> I haven't followed this thread carefully so this may already have been
> suggested: can't you just replace the plot(), lines() calls with
> something like
>
>  matplot(x,t(densities),type='l',lty=1,col=PARAMETERS\$color,
>         ylab = "Density", main = "SPX")
>
> ?
>
> Peter Ehlers
>
>>
>> legend("topright", title = "Distributions", legend = PARAMETERS[,
>> "label"], lwd = 1, col = PARAMETERS[, "color"])
>> grid()
>>
>> Hope this helps,
>>
>> Michael
>>
>>
>> On Sat, Feb 25, 2012 at 2:22 AM, R. Michael Weylandt
>> <michael.weylandt at gmail.com>  <michael.weylandt at gmail.com>  wrote:
>>>
>>> Easiest thing to do: use the optional ylim argument to plot (taking
>>> values like c(0, maxhx) or possibly a little wider) which will let you set
>>> the bounds directly.
>>>
>>> Michael
>>>
>>> PS It's possible to get the following to be much more easily extensible
>>> using loops and what not, but as its very late in my time zone, I'll wait
>>> til the morning to work it out (for fear of making yet another public
>>> mistake :-P) For now, note that it's perfectly ok to use
>>>
>>> maxhx<- max(hx1, hx2, hx3)
>>>
>>> which will save you a few lines.
>>>
>>> On Feb 24, 2012, at 5:58 PM, FJ M<chicagobrownblue at hotmail.com>  wrote:
>>>
>>>>
>>>> I am plotting three Pearson Type IV distributions. It looks like I have
>>>> to plot the distribution with the highest value of y and then use lines() to
>>>> add the two distributions that are shorter / have lower max values of y. The
>>>> following code figures out which distribution has the max y value, plots it
>>>> first and then uses lines for the other two distributions with a series of
>>>> three if statements. This works. I run R from a batch file that reads the
>>>> following in a text file.
>>>>
>>>> I want to graph dozens of distributions and I am looking for a more
>>>> elegant way to do this.
>>>>
>>>> New to R, experienced C programmer, thanks in advance. Frank
>>>>
>>>>
>>>>
>>>> colors<- c("red", "blue", "darkgreen", "gold", "black")
>>>> labels<- c("1", "2","3")
>>>> pdf("C:\\Users\\Frank\\Documents\\R\\Scripts\\pt4_Graph.pdf")
>>>> ## load Pearson package
>>>> library(PearsonDS)
>>>> ##range for x axis
>>>> no_of_increments<- 100
>>>> x<- seq(-0.06, +0.06, length=no_of_increments)
>>>> ##parameters for the plots of three distributions
>>>> mx<- c(1.95, 18.35,1.93)
>>>> nux<- c(0.08,-1.02,0.25)
>>>> locationx<- c(0.0048,-0.00254,0.00189)
>>>> scalex<- c(0.0115,0.082187,0.026675)
>>>> ## calculate probability density function
>>>> hx1<-
>>>> dpearsonIV(x,m=mx[1],nu=nux[1],location=locationx[1],scale=scalex[1])
>>>> hx2<-
>>>> dpearsonIV(x,m=mx[2],nu=nux[2],location=locationx[2],scale=scalex[2])
>>>> hx3<-
>>>> dpearsonIV(x,m=mx[3],nu=nux[3],location=locationx[3],scale=scalex[3])
>>>> ##calculate max of each distribtion
>>>> maxhx1<- max(hx1)
>>>> maxhx2<- max(hx2)
>>>> maxhx3<- max(hx3)
>>>> maxhx<- max(hx1,hx2,hx3)
>>>> maxhx1
>>>> maxhx2
>>>> maxhx3
>>>> maxhx
>>>>
>>>> if (maxhx1==maxhx)
>>>> {plot(x, hx1 , type="l", lwd=2, col=colors[1], xlab="x value",
>>>>  ylab="Density", main="pt4")
>>>> for (i in 2:3){
>>>>  lines(x,
>>>> dpearsonIV(x,m=mx[i],nu=nux[i],location=locationx[i],scale=scalex[i]),
>>>> lwd=2, col=colors[i])}
>>>> legend("topright", inset=.05, title="Distributions",
>>>>  labels, lwd=2, lty=c(1, 1, 1, 1, 2), col=colors)
>>>> grid()
>>>> }
>>>>
>>>> if (maxhx2==maxhx) {plot(x, hx2 , type="l", lwd=2, xlab="x value",
>>>>  ylab="Density", main="SPX", col=colors[2])
>>>> {
>>>>  lines(x,
>>>> dpearsonIV(x,m=mx[1],nu=nux[1],location=locationx[1],scale=scalex[1]),
>>>> lwd=2, col=colors[1])
>>>>  lines(x,
>>>> dpearsonIV(x,m=mx[3],nu=nux[3],location=locationx[3],scale=scalex[3]),
>>>> lwd=2, col=colors[3])
>>>> legend("topright", inset=.05, title="Distributions",
>>>>  labels, lwd=2, lty=c(1, 1, 1, 1, 2), col=colors)
>>>> grid()
>>>> }
>>>>
>>>> if (maxhx3==maxhx)
>>>> {plot(x, hx3 , type="l", lwd=2, col=colors[3], xlab="x value",
>>>>  ylab="Density", main="SPX")
>>>> for (i in 1:2){
>>>>  lines(x,
>>>> dpearsonIV(x,m=mx[i],nu=nux[i],location=locationx[i],scale=scalex[i]),
>>>> lwd=2, col=colors[i])}
>>>> legend("topright", inset=.05, title="Distributions",
>>>>  labels, lwd=2, lty=c(1, 1, 1, 1, 2), col=colors)
>>>> grid()
>>>> }
>>>>
>>>>
>>>> ______________________________________________
>>>> R-help at r-project.org mailing list
>>>> 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.
>>
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> 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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