parsing csv files and accessing a particular column value

hi all,

i am parsing a csv text file as follows:

data = genfromtxt(filename, delimiter=delimiter, dtype=None, names=True)

this returns an array. sometimes though i want to access the element
that has value x in, say, the first column. i usually do this like

nonzero(data['first_column'] == x)

which returns the indices that match. is there a more efficient way to
do this? i'm willing to assume that the values in this column are
unique, so a dict like structure might work. however, i prefer to use
a built in function that might do something like this... is there a
way to do this with the array returned by genfromtxt for example?

thank you.