Uniqueness for list of lists

user_151937 0
Viewed 84934

I am curious what would be an efficient way of uniquifying such data objects:

testdata =[ ['9034968', 'ETH'], ['14160113', 'ETH'], ['9034968', 'ETH'], ['11111', 'NOT'], ['9555269', 'NOT'], ['15724032', 'ETH'], ['15481740', 'ETH'], ['15481757', 'ETH'], ['15481724', 'ETH'], ['10307528', 'ETH'], ['15481757', 'ETH'], ['15481724', 'ETH'], ['15481740', 'ETH'], ['15379365', 'ETH'], ['11111', 'NOT'], ['9555269', 'NOT'], ['15379365', 'ETH']
]

For each data pair, left numeric string PLUS the type at the right tells the uniqueness of a data element. The return value should be a list of lists as same as the testdata, but with only the unique values kept.

unique python
7 Answers

Use unique in numpy to solve this:

import numpy as np

np.unique(np.array(testdata), axis=0)

Note that the axis keyword needs to be specified otherwise the list is first flattened.

Alternatively, use vstack:

np.vstack({tuple(row) for row in testdata})
user_75795470

Expanding a bit on @Mark Byers solution, you can also just do one list comprehension and typecast to get what you need:

testdata = list(set(tuple(x) for x in testdata))

Also, if you don't like list comprehensions as many find them confusing, you can do the same in a for loop:

for i, e in enumerate(testdata):
    testdata[i] = tuple(e)
testdata = list(set(testdata))
user_48810950

if you have a list of objects than you can modify @Mark Byers answer to:

unique_data = [list(x) for x in set(tuple(x.testList) for x in testdata)]

where testdata is a list of objects which has a list testList as attribute.

user_59056780

I was about to post my own take on this until I noticed that @pyfunc had already come up with something similar. I'll post my take on this problem anyway in case it's helpful.

testdata =[ ['9034968', 'ETH'], ['14160113', 'ETH'], ['9034968', 'ETH'], ['11111', 'NOT'], ['9555269', 'NOT'], ['15724032', 'ETH'], ['15481740', 'ETH'], ['15481757', 'ETH'], ['15481724', 'ETH'], ['10307528', 'ETH'], ['15481757', 'ETH'], ['15481724', 'ETH'], ['15481740', 'ETH'], ['15379365', 'ETH'], ['11111', 'NOT'], ['9555269', 'NOT'], ['15379365', 'ETH']
]
flatdata = [p[0] + "%" + p[1] for p in testdata]
flatdata = list(set(flatdata))
testdata = [p.split("%") for p in flatdata]
print(testdata)

Basically, you concatenate each element of your list into a single string using a list comprehension, so that you have a list of single strings. This is then much easier to turn into a set, which makes it unique. Then you simply split it on the other end and convert it back to your original list.

I don't know how this compares in terms of performance but it's a simple and easy-to-understand solution I think.

user_19077650
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