How fit a point on a ecdf curve

Question

I have a random serie of values, a <- runif(1000, 0, 10), and a single value: b <- 1.5 . I want to plot the ecdf, and put on it the value to see the probability to have it.

But when i do that:

plot(ecdf(a))
points(b, col = 'red', lwd = 2)

The points doesn't appear. I think i have to fit the points with the curve to find the y axis value which correspond to it, but i don't really know how to do it. If someoane can help me. Thanks!

score 0 · Accepted Answer · answered May 28 '15 at 09:38

0

ecdf returns a function. You can do this:

set.seed(42)
a <- runif(1000, 0, 10)
b <- 1.5

e <- ecdf(a)

plot(e)
points(b, e(b), col = 'red', cex= 2)

resulting plot

answered May 28 '15 at 09:38

Roland

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Thanks! I just don't understand why you used `set.seed` in the beginning of your code? – User123456789 May 28 '15 at 09:51
To make the random numbers reproducible. – Roland May 28 '15 at 10:47

How fit a point on a ecdf curve

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