Pandas `map`, `applymap` 또는 `apply`를 언제 사용합니까?

import pandas as pd

# Create a Series
series = pd.Series([1, 2, 3, 4, 5])

# Apply a function to each element
def square(x):
    return x**2

# Apply the function to the series using map
squared_series = series.map(square)

print(squared_series)

0    1
1    4
2    9
3   16
4   25
dtype: int64

# Create a DataFrame
df = pd.DataFrame({'a': [1, 2, 3], 'b': [4, 5, 6]})

# Apply a function to each element of the DataFrame
def format_number(x):
    return "{:.2f}".format(x)

# Apply the function to the DataFrame using applymap
formatted_df = df.applymap(format_number)

print(formatted_df)

   a  b
0  1.00  4.00
1  2.00  5.00
2  3.00  6.00

# Apply a function to each row of the DataFrame
def get_max_min_diff(row):
    return row.max() - row.min()

max_min_diff = df.apply(get_max_min_diff, axis=1)

print(max_min_diff)

0    3.00
1    3.00
2    3.00
dtype: float64