Applying Unique over columns in a DataFrame

Question

I have data having over 385 features, to find uniques for a column i have used df.unique() function. However I have to find unique values over all 385 columns.

I tried using for loop as under,

col = [df_train.columns]

for i in col:
    print(i.unique())

I'm getting an output as under

Index(['ID', 'y', 'X0', 'X1', 'X2', 'X3', 'X4', 'X5', 'X6', 'X8',
       ...
       'X375', 'X376', 'X377', 'X378', 'X379', 'X380', 'X382', 'X383', 'X384',
       'X385'],
      dtype='object', length=366)

However the above are the columns names of the dataset and not the unique values of each columns.

I'm doing a concept error when I'm applying for loop, it would be appreciated to correct me where I'm going wrong or an alternative method to do the same.

Thanks in advance.

Sociopath · Accepted Answer · 2019-12-16 10:44:06Z

1

for i in df_train.columns:
    print(df_train[i].unique())

If you do

print(df_train.columns)

It will give you only column names

eg. ["x0","x1","x2"] etc

You need to use indexing to access column values like df_train["column_name"]

edited Dec 16, 2019 at 10:44

answered Dec 16, 2019 at 10:39

Sociopath

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1 Comment

Sid Over a year ago

If you have time, can you please explain where did I go wrong in my above code? So that I can avoid concept errors going further.

Prince Francis · Accepted Answer · 2019-12-16 10:46:12Z

0

to find unique values in a dataframe, we can use describe method as follows

df.describe().loc['unique']

answered Dec 16, 2019 at 10:46

Prince Francis

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Joe · Accepted Answer · 2019-12-16 10:46:51Z

0

Try to run the unique() method per column:

col = df.columns.values.tolist()
unique_vals_list = []

for column in col:
    unique_vals_list.append(list(df[column].unique()))

Your unique_vals_list will now contain all the unique value per column. This will be a list of list, so per index is actually the same index of your dataframe.

So accessing all unique for your first column will have the syntax:

unique_vals_list[0]

Accessing the 2nd column unique values:

unique_vals_list[1]

And so on.

answered Dec 16, 2019 at 10:46

Joe

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