List equality in Python

Question

Making a KMeans clustering algorithm here: Getting stuck on list equality

#clusters = [[],[]]
prevclusters = list(clusters) # Making a new list using clusters elements.
.....
clusters[loc].append(inputs[i]) # Modifying clusters in a for loop
....
# Now, clusters = [[[1, 1], [1, 2]], [[3, 7], [4, 5], [5, 5]]]
if prevclusters == clusters: # Gives True, why ?

Answer 1

When editing the item at loc in cluster , both lists still reference the same sublist, which has been modified. You may want to copy.deepcopy the list when creating prevclusters :

from copy import deepcopy

prevclusters = deepcopy(clusters)