• dominic jones (10/10) Oct 10 2013 Hello,
• bearophile (8/13) Oct 10 2013 Generally it's a good idea to use only pure functions inside the
• Simen Kjaeraas (7/19) Oct 10 2013 You've got the order wrong - copy takes first the source, then the targe...
• bearophile (5/7) Oct 10 2013 I'd like it to be (re)named "copyTo" to avoid me such common

"dominic jones" <dominic.jones gmx.co.uk> writes:

Hello,

I want to fill an array with random numbers without resorting to 
loops, i.e. by doing something like the following, if it were 
possible:

   fill!(function double(){ return uniform(0.0, 1.0);})(x[]);

Is there a simple way of doing this?

Thank you,
Dominic Jones

P.S. I am aware of the function uniformDistribution, but it makes 
the sum of the elements equal to 1, which I don't want.

"bearophile" <bearophileHUGS lycos.com> writes:

dominic jones:

 I want to fill an array with random numbers without resorting 
 to loops, i.e. by doing something like the following, if it 
 were possible:

   fill!(function double(){ return uniform(0.0, 1.0);})(x[]);

 Is there a simple way of doing this?

Generally it's a good idea to use only pure functions inside the 
higher order functions of Phobos. using impure functions like 
uniforms could lead to bugs or performance problems.

This is a way to do it (untested):

x.copy(x.length.iota.map!(_ => uniform(0.0, 1.0));

Bye,
bearophile

"Simen Kjaeraas" <simen.kjaras gmail.com> writes:

On 2013-10-10, 16:04, bearophile wrote:

 dominic jones:

 I want to fill an array with random numbers without resorting to loops,  
 i.e. by doing something like the following, if it were possible:

   fill!(function double(){ return uniform(0.0, 1.0);})(x[]);

 Is there a simple way of doing this?

 Generally it's a good idea to use only pure functions inside the higher  
 order functions of Phobos. using impure functions like uniforms could  
 lead to bugs or performance problems.

 This is a way to do it (untested):

 x.copy(x.length.iota.map!(_ => uniform(0.0, 1.0));

You've got the order wrong - copy takes first the source, then the target.
Also, is it faster to use .length.iota than simply mapping on x?
My solution:

x.map!(_=>uniform(0.0, 1.0)).copy(x);

-- 
Simen

"bearophile" <bearophileHUGS lycos.com> writes:

Simen Kjaeraas:

 You've got the order wrong - copy takes first the source, then 
 the target.

I'd like it to be (re)named "copyTo" to avoid me such common 
mistake.

Bye,
bearophile