Pandas Series

Definition: A Series is a one-dimensional labelled array — think of it as a single column with an index. It is the building block of a DataFrame.

Example 1 — a simple Series

import pandas as pd
s = pd.Series([10, 20, 30, 40])
print(s)
print(s[0])      # 10 (by position)
print(s.sum())   # 100

The numbers on the left (0,1,2,3) are the index — labels for each value.

Example 2 — custom labels

import pandas as pd
s = pd.Series([85, 90, 78], index=["maths", "science", "english"])
print(s)
print(s["science"])   # 90 (by label)

Example 3 — from a dictionary

import pandas as pd
prices = pd.Series({"pen": 2, "book": 8, "bag": 25})
print(prices)
print(prices["book"])

💡 Tip: a Series gives you NumPy speed plus meaningful labels — the best of both worlds.