[R] truehist and density plots

[Uwe Ligges]

carol white wrote:
> OK but how to generalize so that the max of y would cover for all subsets of b? because 50:70 was just an example, so consider other subsets (known or unknow in advance) whose density will be plotted on the histogram.

Take all subsets at first and calculate the max of all those density 
estimates of all substes, then plot all the estimates, as I have done 
for just 1 sample.




> But since b is the full set, why it doesn't contain the max of y for all subsets?

Consult a textbook about statistics:
Consider a density estimate of just very few numbers with very small 
variance (which might happen), you'd get a very high estimate at the center.



Uwe Ligges


> 
> thanks
> 
> --- On Tue, 4/28/09, Uwe Ligges <ligges at statistik.tu-dortmund.de> wrote:
> From: Uwe Ligges <ligges at statistik.tu-dortmund.de>
> Subject: Re: [R] truehist and density plots
> To: "carol white" <wht_crl at yahoo.com>
> Cc: r-help at stat.math.ethz.ch
> Date: Tuesday, April 28, 2009, 6:16 AM
> 
> 
> carol white wrote:
>> Consider a vector of 100 elements (attached files). then, 
>> truehist(b)
>> lines(density(b[20:50]))
>>
>> How is it possible to have density plots of all subsets like b[20:50]
> within histogram (without exceeding the max of historgram on y axis)?
>> Is it more clear?
> 
> 
> Yes, example:
> 
>  # ignore the first plot:
>  truehist(b)
>  yl <- par("usr")[4]
>  d <- density(b[20:50])
> 
>  truehist(b, ylim=c(0, max(yl, d$y)))
>  lines(d)
> 
> 
> Uwe Ligges
> 
> 
> 
>> Best,
>>
>> --- On Tue, 4/28/09, Uwe Ligges <ligges at statistik.tu-dortmund.de>
> wrote:
>> From: Uwe Ligges <ligges at statistik.tu-dortmund.de>
>> Subject: Re: [R] truehist and density plots
>> To: "carol white" <wht_crl at yahoo.com>
>> Cc: r-help at stat.math.ethz.ch
>> Date: Tuesday, April 28, 2009, 5:42 AM
>>
>>
>> carol white wrote:
>>> Hi,
>>> I wanted to plot the histogram of a vector and then, plot the density
>> function of subsets of the vector on the histogram. So I use truehist in
> MASS
>> package and lines(density) as follows:
>>> length(b) = 1000
>>> truehist(b)
>>> lines(density(b[1:100]))
>>
>> I do not undertsand what you mean. Can you please provide a *reproducible*
>> example?
>>
>> Uwe Ligges
>>
>>
>>> however the density plot of the first 100 points exceeds the max of y
> axis
>> (see attached). how is it possible to make a graphics so that the density
> plot
>> of the subsets doesn't go beyond the maximum of all points in the
> complete
>> set?
>>> Cheers,
>>>
>>> Carol
>>>
>>>
>>>
>>>
>>>
>>>
>>>       
>>>
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>>
>>       
> 
> 
>