# Column manipulations:

import pandas as pd

data = [['Alex',10],['Bob',12],['Clarke',13]]

df = pd.DataFrame(data, columns=['x','y'])
print("df:")
print(df)
print(df.dtypes, "\n")
print("-----------------------------")

################################
# Print columns
################################
print("df['x']:")
print(df['x'])
print("-----------------------------")

print("df[['y', 'x']]:")
print(df[['y', 'x']])
print("-----------------------------")

################################
# Add a column
################################

df['z'] = [10,20,30]
print("df:")
print(df)

# Error:
# df['u'] = [10,20,30,40]


################################
# Delete a column
################################
del df['y']
print("df:")
print(df)