# 3.10. Series Arithmetic¶

## 3.10.1. Vectorized Operations¶

• s + 2, s.add(2), s.__add__(2)

• s - 2, s.sub(2), s.subtract(2), s.__sub__(2)

• s * 2, s.mul(2), s.multiply(2), s.__mul__(2)

• s ** 2, s.pow(2), s.__pow__(2)

• s ** (1/2), s.pow(1/2), s.__sub__(1/2)

• s / 2, s.div(2), s.divide(), s.__div__(2)

• s // 2, s.truediv(2), s.__truediv__(2)

• s % 2, s.mod(2), s.__mod__(2)

• divmod(s, 2), s.divmod(2), s.__divmod__(2), (s//2, s%2)

import pandas as pd
import numpy as np

s = pd.Series(
data = [1.1, 2.2, np.nan, 4.4],
index = ['a', 'b', 'c', 'd'])

s
# a    1.1
# b    2.2
# c    NaN
# d    4.4
# dtype: float64

s + 2
# a    3.1
# b    4.2
# c    NaN
# d    6.4
# dtype: float64

s ** 2
# a     1.21
# b     4.84
# c      NaN
# d    19.36
# dtype: float64

s ** (1/2)
# a    1.048809
# b    1.483240
# c         NaN
# d    2.097618
# dtype: float64


• Uses inner join

• fill_value: If data in both corresponding Series locations is missing the result will be missing

import pandas as pd

a = pd.Series([1, 2, 3])
b = pd.Series([4, 5, 6])

a + b
# 0    5
# 1    7
# 2    9
# dtype: int64

import pandas as pd

a = pd.Series([1, 2, 3, 4])
b = pd.Series([4, 5, 6])

a + b
# 0    5.0
# 1    7.0
# 2    9.0
# 3    NaN
# dtype: float64

import pandas as pd

a = pd.Series([1, 2, 3])
b = pd.Series([4, 5, 6, 7])

a + b
# 0    5.0
# 1    7.0
# 2    9.0
# 3    NaN
# dtype: float64

import pandas as pd

a = pd.Series([1, 2, None])
b = pd.Series([4, 5, 6])

a + b
# 0    5.0
# 1    7.0
# 2    NaN
# dtype: float64

import pandas as pd

a = pd.Series([1, 2, None])
b = pd.Series([4, 5, None])

a + b
# 0    5.0
# 1    7.0
# 2    NaN
# dtype: float64

import pandas as pd

a = pd.Series(data=[1, 2, 3], index=['a', 'b', 'c'])
b = pd.Series(data=[4, 5, 6], index=['a', 'b', 'x'])

a + b
# a    5.0
# b    7.0
# c    NaN
# x    NaN
# dtype: float64


fill_value: If data in both corresponding Series locations is missing the result will be missing:

a = pd.Series(data=[1, 2, 3], index=['a', 'b', 'c'])
b = pd.Series(data=[4, 5, 6], index=['a', 'b', 'x'])

# a    5.0
# b    7.0
# c    3.0
# x    6.0
# dtype: float64


## 3.10.3. Assignments¶

"""
* Assignment: Series Arithmetic
* Complexity: easy
* Lines of code: 5 lines
* Time: 5 min

English:
1. Set random seed to zero
2. Generate data: ndarray with 5 random digits [0, 9]
3. Create index: list with index names as sequential letters in english alphabet
4. Create s: pd.Series from data and index
5. Multiply s by 10
6. Multiply s by s
7. Run doctests - all must succeed

Polish:
1. Ustaw random ziarno losowości na zero
2. Wygeneruj data: np.ndarray z 5 losowymi cyframi <0, 9>
3. Stwórz index: list z indeksami jak kolejne listery alfabetu angielskiego
4. Stwórz s: pd.Series z data oraz index
5. Pomnóż s przez 10
6. Pomnóż s przez  wartości s
7. Uruchom doctesty - wszystkie muszą się powieść

Tests:
>>> import sys; sys.tracebacklimit = 0

>>> type(result) is pd.Series
True
>>> result
a    2500
b       0
c     900
d     900
e    4900
dtype: int64
"""

import pandas as pd
import numpy as np
np.random.seed(0)

result = ...