如果差值大于某个值，则在列表中保留连续数字

Question

I would like to keep consecutive values in a list with difference >= than X Let's say I have this list:

list = [1, 50, 70, 75, 100, 110] 

and I would like to keep consecutive number numbers whose difference is >= 20:

A = [1, 50, 70, 100] 

To do this I'm using now this code:

distance = 20
A = []
for i in (list):
    if not A or (i - A[-1]) >= distance:
        A.append(i)

There is any other way to do this with itertools or more-itertools? Thank you!

Answer 1

Try:

>>> arr = np.array([1, 50, 70, 75, 100, 110])
>>> mask = np.diff(arr) >= 20
>>> mask = np.insert(mask, 0, True)
>>> arr[mask]
array([  1,  50,  70, 100])

Answer 2

For list l , we could do -

[l[0]]+[l[i] for i in range(1,len(l)) if l[i]-l[i-1]>=20]

For array a , it would be -

a[np.r_[True,np.diff(a)>=20]]

If you want to consider differences as absolute ones -

a[np.r_[True,np.abs(np.diff(a))>=20]

Answer 3

With simple generator function:

def filter_diff(lst):
    v = lst[0]
    yield v
    for n in range(1, len(lst)):
        if lst[n] - v >= 20:
            v = lst[n]
            yield v

lst = [1, 50, 70, 75, 100, 110]
print(list(filter_diff(lst)))   # [1, 50, 70, 100]