Às 15:27 de 21/04/2025, Brian Smith escreveu:
Hi,
There is a function called RandVec in the package Surrogate which can
generate andom vectors (continuous number) with a fixed sum
The help page of this function states that:
a
The function RandVec generates an n by m matrix x. Each of the m
columns contain n random values lying in the interval [a,b]. The
argument a specifies the lower limit of the interval. Default 0.
b
The argument b specifies the upper limit of the interval. Default 1.
However in my case, the lower and upper limits are not same. For
example, if I need to draw a pair of number x, y, such that x + y = 1,
then the lower and upper limits are different.
I tried with below code
library(Surrogate)
RandVec(a=c(0.1, 0.2), b=c(0.2, 0.8), s=1, n=2, m=5)$RandVecOutput
This generates error with message
Error in if (b - a == 0) { : the condition has length > 1
Is there any way to generate the numbers with different lower and upper limits?
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Hello,
Use ?mapply to cycle through all values of a and b.
Note that the output matrices are transposed, the random vectors are the
rows.
library(Surrogate)
a <- c(0.1, 0.2)
b <- c(0.2, 0.8)
mapply(\(a, b, s, n, m) RandVec(a, b, s, n, m),
MoreArgs = list(s = 1, n = 2, m = 5), a, b)
#> $RandVecOutput
#> [,1] [,2] [,3] [,4] [,5]
#> [1,] 0.2004363 0.1552328 0.2391742 0.1744857 0.1949236
#> [2,] 0.1995637 0.2447672 0.1608258 0.2255143 0.2050764
#>
#> $RandVecOutput
#> [,1] [,2] [,3] [,4] [,5]
#> [1,] 0.2157416 0.4691191 0.5067447 0.7749258 0.7728955
#> [2,] 0.7842584 0.5308809 0.4932553 0.2250742 0.2271045
Hope this helps,
Rui Barradas
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