What is the DataFrame.keys() method in pandas?

Overview

In pandas, the DataFrame.keys() method is used to get the axis info for pandas instance. Pandas instance or object can be either Series or a DataFrame.

  • DataFrame: In the case of DataFrame, it returns an index that contains column names and dataType.
  • Series: For Series, it returns RangeIndex that contains start, stop and step values.

    Note: Axis info contains column names and data type.

    Syntax

    DataFrame.keys()

    Parameter

    It does not take any argument value.

    Return value

    This method returns a Python iterator object.

    DataFrames

    In this example, we discuss keys() with DataFrame:

    # importing pandas as pd alias
    import pandas as pd
    # initializing a nested list
    data = [['China', 15], ['America', 21], ['Pakistan', 0.4]]
    # Creating the DataFrame
    df = pd.DataFrame(data, columns = ['Country', 'GDP'])
    # Print the DataFrame
    print(df.keys())

    In the code snippet above, we create a DataFrame with column names Country and GDP. Next, we invoke the keys() function to get the info axis.

    • Line 4: We create a nested list instance that includes countries and their 2021 GDPs.
    • Line 6: We use pandas to create a DataFrame by using Country and GDP as column names.
    • Line 8: Now, calling keys() to extract info axis.

    Series

    In this example, we discuss keys() with Series:

    # importing pandas as pd
    import pandas as pd
    import numpy as np
    # creating a numpy array
    data = np.array(['e','d','u','c','a','t','i','v','e'])
    # creating a series
    _series = pd.Series(data)
    # to find the index
    print(_series.keys())

    In the code snippet above, we create a series of the character array and invoking keys() to get axis info.

    • Line 5: We create a NumPy array.
    • Line 7: We invoke Series() to convert above create character array into a Series object.
    • Line 9: Next, we call keys() to extract info axis.

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