Question

does anyone know how to write a linear search function in python?

Answer 1

Yes.

Answer 2

By linear, do you mean sequential?

Python has a built-in list function for sequential search, index(). Consider
>>> range(5).index(2)
2

Which tells you that the index if the value '2' in the list '[0,1,2,3,4]' is '2'.

Alternatively, just use a for loop with a sentinel!

>>> some_list = [0,-5,2,25,3]
>>> val_to_search_for = 2
>>> for i in xrange(some_list):
... if some_list[i] == val_to_search_for:
... print i
2