(a) Using the DataFrame ResultDF, write the statement to access Marks of Arnab in Maths.
(b) Create a DataFrame having 5 rows and write the statement to get the first 4 rows of it.
[Context: In the textbook, ResultSheet is a dictionary of five Series — 'Arnab': pd.Series([90, 91,

Question

(a) Using the DataFrame ResultDF, write the statement to access Marks of Arnab in Maths.
(b) Create a DataFrame having 5 rows and write the statement to get the first 4 rows of it.
[Context: In the textbook, ResultSheet is a dictionary of five Series — 'Arnab': pd.Series([90, 91, 97], index=['Maths','Science','Hindi']), and similarly 'Ramit', 'Samridhi', 'Riya', 'Mallika' — and ResultDF = pd.DataFrame(ResultSheet), giving columns Arnab, Ramit, Samridhi, Riya, Mallika with rows Maths: 90 92 89 81 94; Science: 91 81 91 71 95; Hindi: 97 96 88 67 99.]

Accepted Answer

> [!TLDR]
> Part (a) uses `.loc[]` with row label `'Maths'` and column label `'Arnab'` to extract a single cell. Part (b) uses `.head(4)` on any DataFrame to get the first 4 rows.

## (a) Accessing Marks of Arnab in Maths

The DataFrame `ResultDF` is built from a dictionary of Series, where each Series is a student's marks indexed by subject names. This means the **row labels** are the subjects (`'Maths'`, `'Science'`, `'Hindi'`) and the **column labels** are the student names (`'Arnab'`, `'Ramit'`, etc.).

To access a single cell, you need both the row and column label. The pandas tool for label-based access is `.loc[]`. You pass the row label first, then the column label, separated by a comma.

```python
arnab_maths = ResultDF.loc['Maths', 'Arnab']
```

This returns the integer `90`.

> [!WARNING]
> A common mistake is to use `.iloc[]` with integer positions instead of `.loc[]` with labels. While `.iloc[0, 0]` would also give `90` here (since Maths is the first row and Arnab is the first column), this is fragile — if the order of rows or columns changes, `.iloc` breaks. Always use `.loc` when you know the actual labels.

## (b) Creating a DataFrame and Getting First 4 Rows

First, create any DataFrame with at least 5 rows. A simple way is from a dictionary of lists:

```python
import pandas as pd

data = {
    'Name': ['Alice', 'Bob', 'Charlie', 'Diana', 'Eve'],
    'Score': [85, 92, 78, 95, 88]
}
df = pd.DataFrame(data)
``` …

Q.(a) Using the DataFrame ResultDF, write the statement to access Marks of Arnab in Maths.

Concept understanding — Data Type Identification

Data Type Identification

The Core Idea

The Main Categories

Why It Matters in Practice …

(a) Accessing Marks of Arnab in Maths

(b) Creating a DataFrame and Getting First 4 Rows

Q.(a) Using the DataFrame ResultDF, write the statement to access Marks of Arnab in Maths.

(a) Accessing Marks of Arnab in Maths

(b) Creating a DataFrame and Getting First 4 Rows

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