CODEWITHSUNDEEP
pythonnumpy
Bingo Sun
Bingo Sun

Reputation: 1

how do I use numpy find consequent same elements and the index under some condition?

Let's suppose I have two numpy.array():

a = np.array([1,2,3,4,5,6,7,8,9,10,11,12]) #index

b = np.array([1,1,4,3,3,3,5,2,2,2,2,6])    #element

How do I efficiently find all consequent same element whose number of consequent same element >=3 , the start_index and end_index? I hope the result :

c:  array([4,8])  #start_index
d:  array([6,11]) #end_index
e:  array([3,2])  #consequent same values whose number of consequent same element >=3

Upvotes: 0

Views: 301

Answers (1)

Paul Panzer
Paul Panzer

Reputation: 53119

Find the group boundaries:

sw, = np.where(np.diff(b, prepend=1, append=1))

Filter for condition:

cm, = np.where(np.diff(sw)>=3)

Retrieve corresponding indices

c = a[sw[cm]]
d = a[sw[cm+1]-1]

and values

e = b[sw[cm]]

Admire

c
# array([4, 8])
d
# array([ 6, 11])
e
# array([3, 2])

Upvotes: 1

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