"""
Create a DataFrame and use indexes to
"""
import pandas as pd

# Create a dataframe and associate an index to it
df = pd.DataFrame(
    data={"name": ["Mac", "Ann", "Rob"], "age": [33, 44, 55]},
    index=["u1", "u2", "u3"]  # as many values as rows
)

# Show normal DataFrame
print(df)

# Access one row using an index value
print(df.loc["u1"])

# Access the same row using a numerical index
print(df.iloc[0])

# Get a DataFrame with a selection of lines
# To extract this, the selection of lines **must** be a list and not a tuple;
# the tuple is used to select or slice in the other axis.
print(df.loc[["u1", "u3", "u2"]])

# Show the index0
print(df.index)