reindex a pd.Series

Reorder the rows with reindex.

import sys
import pandas as pd

data = {
    "New York":    "The Empire State",
    "New Jersey":  "The Garden State",
    "Connecticut": "The Constitution State"
}

series = pd.Series(data = data, name = "nicknames")
series.index.name = "name"
print(series)
print()

print(f"{series.index = }")
print()

#Keep the same rows, but in a different order.

index = pd.Index(data = sorted(data.keys()), name = "name")   #Create a new index.
series = series.reindex(index = index)
print(series)
print()

print(f"{series.index = }")
sys.exit(0)

name
New York             The Empire State
New Jersey           The Garden State
Connecticut    The Constitution State
Name: nicknames, dtype: object

series.index = Index(['New York', 'New Jersey', 'Connecticut'], dtype='object', name='name')

name
Connecticut    The Constitution State
New Jersey           The Garden State
New York             The Empire State
Name: nicknames, dtype: object

series.index = Index(['Connecticut', 'New Jersey', 'New York'], dtype='object', name='name')

Insert and delete rows with reindex.

import sys
import pandas as pd

data = {
    "New York":    "The Empire State",
    "New Jersey":  "The Garden State",
    "Connecticut": "The Constitution State"
}

series = pd.Series(data = data, name = "nicknames")
series.index.name = "name"
print(series)
print()

print(f"{series.index = }")
print()

#Delete "Connecticut", insert "New Mexico".

index = pd.Index(data = ["New York", "New Mexico", "New Jersey"], name = "name")   #Create a new index.
series = series.reindex(index = index, fill_value = "The Unknown State")
print(series)
print()

print(f"{series.index = }")
sys.exit(0)

name
New York             The Empire State
New Jersey           The Garden State
Connecticut    The Constitution State
Name: nicknames, dtype: object

series.index = Index(['New York', 'New Jersey', 'Connecticut'], dtype='object', name='name')

name
New York       The Empire State
New Mexico    The Unknown State
New Jersey     The Garden State
Name: nicknames, dtype: object

series.index = Index(['New York', 'New Mexico', 'New Jersey'], dtype='object', name='name')

What do you get if you don’t specify a fill_value?