0

I have a list = [0, 0, 7] and I when I compare it against anotherList = [0, 0, 7, 0] using in it gives me False.

I would like to know how I can check if numbers in one list are in the same sequence as another list.

So, if I do anotherList2 = [7, 0, 0, 0]:

list in anotherList2 returns False

But, list in anotherList return True

Bob
  • 25
  • 2
  • 6
  • 1
    You shouldn't name lists `list`, it overrides a builtin name. Also, `list in anotherList` will return False here, not True – user3483203 Jun 27 '18 at 01:44
  • In this case, `in`, checks if the list is an element of `anotherList`, not if the elements of `list` are contained in `anotherList`. If you do `anotherList.append(list)` and then `list in anotherList`, you will see it returns True – user3483203 Jun 27 '18 at 01:47
  • 3
    Construct a sliding window iterator over the larger dataset, and see if any of those windows are equal to your first list: https://stackoverflow.com/questions/6822725/rolling-or-sliding-window-iterator – Patrick Haugh Jun 27 '18 at 01:48

4 Answers4

2

Here's a one-liner function that will check if list a is in list b:

>>> def list_in(a, b):
...     return any(map(lambda x: b[x:x + len(a)] == a, range(len(b) - len(a) + 1)))
...
>>> a = [0, 0, 7]
>>> b = [1, 0, 0, 7, 3]
>>> c = [7, 0, 0, 0]
>>> list_in(a, b)
True
>>> list_in(a, c)
False
>>>
blhsing
  • 91,368
  • 6
  • 71
  • 106
0

You have to check each position in the list one by one. start iterating through anotherList

if the first element of list is same as the current element in the anotherList start checking until you find the whole sequence

The program goes here:

def list_in(list,anotherList):
    for i in range(0,len(anotherList)):
        if(list[0]==anotherList[i]):
            if(len(anotherList[i:]) >= len(list)):
                c=0
                for j in range(0,len(list)):
                    if(list[j]==anotherList[j+i]):
                        c += 1
                        if(c==len(list)):
                            print("True")
                            return
                    else:
                        continue


    print("False")
    return
list = [0,0,7]
anotherList = [0,0,7,0]
anotherList2 = [7,0,0,0]

list_in(list,anotherList)
list_in(list,anotherList2)
Rupesh Kumar
  • 1
  • 2
  • 2
    This will give false positives when the lists contain numbers of multiple digits and the adjacent digits of two numbers in a list happen to match the those of two different numbers in the other list. For example, `[12, 3]` and `[1, 23]` will match using your method, which is incorrect. – blhsing Jun 27 '18 at 02:02
  • Yes, I have solved it by making a function and checking each number one by one – Rupesh Kumar Jun 27 '18 at 02:27
0

Using slices it's pretty simple to write an efficient function that does what you're looking for:

def sequence_in(seq, target):
    for i in range(len(target) - len(seq) + 1):
        if seq == target[i:i+len(seq)]:
            return True
    return False

Which we can use like this:

sequence_in([0, 1, 2], [1, 2, 3, 0, 1, 2, 3, 4])
Matthew Story
  • 3,573
  • 15
  • 26
0

There are some great answers here, but here's another way you could tackle it using strings as a medium.

def in_ist(l1, l2):
    return ''.join(str(x) for x in l1) in ''.join(str(y) for y in l2)

This basically turns the elements of the lists into strings and uses the in operator, which does what you'd expect in this case, checking whether l1 is in l2.

Kobee Raveendran
  • 41
  • 3