How to delete unique items in an array

akadeco

Hi

I need to write a program and part it's functionality is to delete unique items in an array. That is, delete items in the array that only occur once.

I also need to delete the first occurrence of repeated items, and I'm pretty sure the solution to these two will go hand in hand.

Thanks

akadeco

bvdet

akadeco,

Are you asking for help with your assignment? We can't help until you show some effort to solve this yourself.

BV
Moderator

kudos

(I guess the assignment is too small to be a school assignment)

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a = [1,2,3,4,3,4,4,4,5,6]

b = {}

i = 0

for c in range(len(a)):

 if(b.has_key(a[i]) == False):

  b[a[i]] = 1

  a.remove(a[i])

 else: 

  i+=1

print a

-kudos

Quote:

Originally Posted by akadeco

Hi

I need to write a program and part it's functionality is to delete unique items in an array. That is, delete items in the array that only occur once.

I also need to delete the first occurrence of repeated items, and I'm pretty sure the solution to these two will go hand in hand.

Thanks

akadeco

bvdet

Here's another way that creates a new list.

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 >>> a = [1,2,3,4,3,4,4,4,5,6]

>>> b = []

>>> for j, item in enumerate(a):

...     if a.count(item) > 1 and j > a.index(item):

...         b.append(item)

...         

>>> b

[3, 4, 4, 4]

>>>

kudos

Expand|Select|Wrap|Line Numbers

 
a = [1,2,3,4,3,4,4,4,5,6]

b=[]

for c in a:

 if(a.count(c) >=2 and b.count(c) < a.count(c)-1):

  b.append(c)

print b

Can we avoid using the list 'b'?

-kudos

bvdet

With a list comprehension:

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 >>> a = [item for j, item in enumerate(a) if a.count(item) > 1 and j > a.index(item)]

>>> a

[3, 4, 4, 4]

>>>

akadeco

@Kudos thank you so much that is exactly what I needed!

Thank you all for your swift replies

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