Map list to list of lists by index (Python) -

i'm looking efficient way map list of values,

x = [1,2,3,4,5,6,7,8,9]  

to list, containing lists of values of same total range, example

z = [[1,2,3], [4,5,6], [7,8,9]].  

what need know index value x corresponds in z. x[0]=1 correspond z[0], because falls in first bin of z, x[7]=8 correspond z[2], because falls in third bin.

how identify index of sublists of z each x value? in case, x has 50,000 values, z has 5,000 sublists, , have lots of lists, i'm looking way fast possible.

you can use dict here:

>>> x = [1,2,3,4,5,6,7,8,9] >>> z = [[1,2,3], [4,5,6], [7,8,9]] >>> dic = {y :i i,a in enumerate(z) y in a} >>> dic[7] 2 >>> dic[8] 2 >>> dic[1] 0