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Although, one must always themselves determine the range of x when using curve() in R, I was wondering how I could get the last x used (i.e., to =) after a curve() is executed in R?

For example, if I save a curve() as an object called cc, I can get the first x (i.e., from =) from the curve() using: cc$x[1] (see below). But how can I get the last x used in this curve()?

As an example ]

cc = curve(dchisq(6, df = 3, ncp = x ), from = 0, to = 10, col = 'red')

First.x.used.in.curve = cc$x[1]

Last.x.used.in.curve = ?     ## How can I find this?

1 Answers1

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Just use tail to get the last n elements of the vector cc$x

tail(x = cc$x, n = 1)
#[1] 10

Other possible ways would be 

rev(cc$x)[1] #Reverse and access the first element of the reversed vector
#[1] 10

#OR

cc$x[length(cc$x)] #Index the last element by using the length of the vector
#[1] 10
d.b
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  • Dear d.b, do you think you could possibly answer [**THIS QUESTION**](http://stackoverflow.com/questions/43688786/scaling-up-a-curve-line-such-that-it-can-be-shown-along-side-another-curve-line)? –  Apr 28 '17 at 21:10