Is there a good way to map vectors? Here's an example of what I mean:

vec0 = [0,0,0,0,0,0,0,0,0,0,0]
vec1 = [1,4,2,7,3,2]
vec2 = [0,0,0,0,0,0,0,0,0]
vec2 = [7,2,7,9,9,6,1,0,4]
vec4 = [0,0,0,0,0,0]

mainvec =
[0,0,0,0,0,0,0,0,0,0,0,1,4,2,7,3,2,0,0,0,0,0,0,0,0,0,7,2,7,9,9,6,1,0,4,0,0,0,0,0,0]

Lets say mainvec doesn't exist (I'm just showing it to you so you can see the general data structure in mind.

Now say I want mainvec(12) which would be 4. Is there a good way to map the call of these vectors without just stitching them together into a mainvec? I realize I could make a bunch of if statements that test the index of mainvec and I can then offset each call depending on where the call is within one of the vectors, so for instance:

mainvec(12) = vec1(1)

which I could do by:

mainvec(index)
if (index >=13)
    vect1(index-11);

I wonder if there's a concise way of doing this without if statements. Any Ideas?