Choosing a random number between x and y

Hi,

Ive been trying to find a function that will allow me to pull out a number
between a minimum and maximum threshold.

I want a random decimal number between, for example, 0 and 0.5 or 0 and 0.7.
I've been searching everywhere for a function that will allow me to do this
in R, but I have yet to be successful. Any help would be much appreciated.

Thanks in advance

Hi Vie 

I don't understand if you need a only random generation or mixture
random generation, so i will make the 3 examples Using runif

1- Random 10 number Retween 0 and 0.5 runif(10,0,0.5)

2 -Random 20 number Retween 0 and 0.7 runif(20,0,0.7)

3- Random 40 number of mixture two random uniforme random 1 and 2 with
p(random1)= 0.3 and p(random=2) = 0.7

ifelse(runif(40)>.3,runif(40,0,0.7),runif(40,0,0.5))

Bernardo Rangel Tura, M.D,MPH,Ph.D
National Institute of Cardiology
Brazil