Given columns of data, I need to count occurances, based
on certain data.

aa 0123 red 3
ab 0125 red 3
ac 0452 blue 5
ba 0478 white 12
bb 0845 white 1
bc 0654 red 54

I need to only look at data that starts with a "b" (first
column), then I want to count how many colours (3rd
column) have numbers less than "4" (last column).

I suppose that the function should have the colour as an
argument, so when it is called it will return the number
of occurances.

Can anyone help me please.

Simon