[R] Can't mix high level and low level plot functions.

[Lothar Botelho-Machado]

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Thanks for your help!!

I appreciate, now it works perfectly.

Lothar Rubusch



Duncan Murdoch wrote:
> On 9/25/2006 1:56 PM, Lothar Botelho-Machado wrote:
>> Hey R-Comunity,
>>
>>
>> I'd like to print out an histogram of some experimental data and add a
>> smooth curve of a normal distribution with an ideally generated
>> population having the same mean and standard deviation like the
>> experimental data.
>>
>>
>> The experimental data is set as vector x and its name is set to
>> group.name. I paint the histogram as follows:
>>
>> hist(data, freq=FALSE, col="lightgrey", ylab="Density", xlab=group.name)
>>
>>
>>
>> First I did the normal distribution curve this way:
>>
>> lines(x, dnorm(x, mean=mean(x), sd=sd(x)), type="l", lwd=2)
>>
>> This curve just uses as many values as there are in x. When using small
>> amounts of sample populations the curve looks really shaky.
> 
> This is generally the right way to do it, but you likely want to use a
> different variable for the first two occurrences of x, e.g.
> 
> x0 <- seq(from=min(x), to=max(x), len=200)
> lines(x0, dnorm(x0, mean=mean(x), sd=sd(x)), type="l", lwd=2)
> 
> Duncan Murdoch
> 
>>
>>
>> I tried this one using a high level plot function as well:
>>
>> curve(dnorm, n=10000, add=TRUE, xlim=range(x))
>>
>> The advantage is, now I can set an ideal population of 10000 to get the
>> ideal curve really smooth. But the big disadvantage is, I don't know how
>> to add "mean=mean(x),  sd=sd(x)" arguments to it? It says that it can't
>> mix high level with low level plot functions when I try to set some kind
>> of parameter like "n=10000" to the low level function, it says that
>> there ain't enough x values.
>>
>> So my question is, how to get a smooth curve placed of dnorm over an
>> histogram of sample data, ideally by using the curve method?
>>
>>
>> TIA,
>> Lothar Rubusch
>>
>> ______________________________________________
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>> and provide commented, minimal, self-contained, reproducible code.
> 
> 


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