how to make array from elements inside another array

[madomado60]

how to make array from elements inside another array ???

[DeathLeap]

http://lmgtfy.com/?q=how+to+make+array+from+elements+inside+another+array

[integralfx]

foo is an array that you want to copy data from
bar is an empty array of the same length as foo

for every element in foo
	bar[index] = foo[index]

[madomado60]

i want to get specific elements not all elements as foo[2], foo[4] for example put them in bar[0] bar[1]

[keskiverto]

Conceptually:

 for interesting elements in foo
   bar[ fbmap(index) ] = foo[ index ]

or

 for every element in bar
   bar[ index ] = foo[ bfmap(index) ]

where the functions fbmap() and bfmap() represent mapping from valid indices of one array into valid indices of the other array.