Chapter 13

NumPy → pandas

DataFrame = array + labels

A pandas DataFrame is a 2-D array with labels: df.index names the rows, df.columns names the columns. The values are an ndarray you already know — df.to_numpy() gives it back.

Edit the labels, or the numbers above. pandas runs here for real (it downloads once, ≈ 5 MB).

Try this

Remember: DataFrame = 2-D values + row labels (index) + column labels (columns).

a = dtype shape (2, 3)

Try

Spaces or commas between values · new line = new row · blank line = new 2-D layer (3-D array).

real pandas 3.0.2 · runs here

Starting Python… (first visit downloads ≈ 15 MB, then it is cached)

index · row labels columns · column labels

Words become text labels ('r0'), whole numbers become number labels (10).

a ndarray (2, 3)

Python not started

import numpy as np
import pandas as pd

a = np.array([[1, 2, 3],
              [4, 5, 6]])

df = pd.DataFrame(a, index=['r0', 'r1'], columns=['A', 'B', 'C'])
values = df.to_numpy()   # the array inside, without labels

df

Output

Output appears here.