count unique values in array python code example

Example 1: how to count number of unique values in a column python

pd.value_counts(df.Account_Type)

Gold        3
Platinum    1
Name: Account_Type, dtype: int64

Example 2: python count number of unique elements in a list

# Basic syntax:
len(set(my_list))
# By definition, sets only contain unique elements, so when the list
# is converted to a set all duplicates are removed. 

# Example usage:
my_list = ['so', 'so', 'so', 'many', 'duplicated', 'words']
len(set(my_list))
--> 4

# Note, list(set(my_list)) is a useful way to return a list containing
#	only the unique elements in my_list

Example 3: count unique values pandas

df['hID'].nunique()
5

Example 4: count unique values in python

aa="XXYYYSBAA"
bb=dict(zip(list(aa),[list(aa).count(i) for i in list(aa)]))
print(bb)
# output:
# {'X': 2, 'Y': 3, 'S': 1, 'B': 1, 'A': 2}

Example 5: count unique values in python

words = ['a', 'b', 'c', 'a']
unique_words = set(words)             # == set(['a', 'b', 'c'])
unique_word_count = len(unique_words) # == 3