Operation with Arrays in Python

Question

I have an array of binary numbers in Python like this:

binary = [1,1,0,1,1,0,0]

So, I wanna have a method to return how many times is a sequence of binary number, for example:

binary = [1,1,0,1,1,0,0]

must return 4, because there are 1 sequence of 'twice 1', after there is a sequence of 'one 0', then there are a sequence of 'twice 1' and finally a sequence of 'twice 0'

other example:

binary = [1,0,0,1,1,1,1]

must return 3, because there is 1 sequence of 'one 1', after there are a sequence of 'twice 0', finally there are a sequence of 'four 1s.'

Thank you so much.

Answer 1

This is trivial with itertools.groupby():

from itertools import groupby

binary_lists = [[1,1,0,1,1,0,0],
                [1,0,0,1,1,1,1],
                '1111111111',
                '1',
                [0],
                [1,0,1,0,1,0,1],
                [],
                '',
                'aaccgta']

for bits in binary_lists:
    print '{} : num sequences = {}'.format(bits, len(list(groupby(bits)))) 

Output:

[1, 1, 0, 1, 1, 0, 0] : num sequences = 4
[1, 0, 0, 1, 1, 1, 1] : num sequences = 3
1111111111 : num sequences = 1
1 : num sequences = 1
[0] : num sequences = 1
[1, 0, 1, 0, 1, 0, 1] : num sequences = 7
[] : num sequences = 0
 : num sequences = 0
aaccgta : num sequences = 5

Answer 2

Any ideas how to improve?

def countSeq(src):
  last = src[0]
  count = 0
  current = 1
  while current < len(src):
    if src[current] != last:
      count += 1
      last = src[current]
    current += 1
  return count + 1 # last

Test:

>>> countSeq([1,1,0,1,1,0,0])
4
>>> countSeq([1,0,0,1,1,1,1])
3