I have a long list which consist of two fixed possible numbers (0 and 1). e.g:
l = [0,0,0,0,0,1,1,1,1,1,1,1]
I don’t know which number occurs first in the list but I am sure that if 0 is occurring first in the list then it will occur consecutively followed by 1, same case for 1.
I am performing some kind of action on the basis of these number conditions (0,1) but also I need to show a message before the first occurrence of 0 and 1.
First occurrence of first number (in this case 0), I have managed like this.
if l[0] == 0: print ('first occurrence of 0') elif l[0] == 1: print ('first occurrence of 1')
I am not sure how to point out first occurrence of 1 during execution of this list.
For this example list I need result like this.
msg before first occurrence of 0 0 0 0 0 0 msg before first occurrence of 1 1 1 1 1 1 1 1
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Answer
A solution that works for more than just 0 and 1 can be based to a set
containing the elements we encountered so far:
l = [0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1] s = set() for x in l: if x not in s: print("first occurrence of %s" % x) s.add(x) print(x)
Result:
first occurrence of 0 0 0 0 0 0 first occurrence of 1 1 1 1 1 1 1 1