Find an element in a list of tuples

Question

I have a list \'a\'

a= [(1,2),(1,4),(3,5),(5,7)]

I need to find all the tuples for a particular number. say for 1 it will be

Answer 1

If you just want the first number to match you can do it like this:

[item for item in a if item[0] == 1]

If you are just searching for tuples with 1 in them:

[item for item in a if 1 in item]