Class 12 Data Handling using Pandas - I Mock Test (CBSE)

Topics in Data Handling using Pandas - I

• Introduction to Python libraries
• Series: creation
• Accessing elements of a series
• Attributes and methods of series
• Mathematical operations on series
• DataFrame: creation
• Operations on rows and columns in DataFrames
• Accessing DataFrame elements through indexing
• Accessing DataFrame elements through slicing
• Attributes of DataFrames
• Importing and exporting data between CSV files and DataFrames
• Pandas series versus NumPy ndarray

Data Handling using Pandas - I practice questions with answers

1. Q1Multiple choice·1 mark
   Which statement correctly distinguishes the pandas function read_csv() from the DataFrame method to_csv()?

   1. (a)read_csv() writes a DataFrame to a CSV file, while to_csv() reads a CSV file into a DataFrame.
   2. (b)read_csv() reads a CSV file into a DataFrame, while to_csv() writes a DataFrame to a CSV file.
   3. (c)Both read_csv() and to_csv() work only on Series objects and never on DataFrames.
   4. (d)read_csv() returns a NumPy ndarray, while to_csv() returns a Series holding the file contents.
   Show answer and step marks

   1. Correct option: (b) read_csv() reads a CSV file into a DataFrame, while to_csv() writes a DataFrame to a CSV file.+1

   Answer: (b)
2. Q2Multiple choice·1 mark
   Which of the following best describes a Python library?

   1. (a)A file that permanently stores a DataFrame on disk in CSV format.
   2. (b)A single built-in data type used to store a sequence of values.
   3. (c)A graphical window in which Python code is typed and run.
   4. (d)A collection of pre-written modules and functions that is imported with the import statement.
   Show answer and step marks

   1. Correct option: (d) A collection of pre-written modules and functions that is imported with the import statement.+1

   Answer: (d)
3. Q3Short answer·2 marks
   A Series named quiz is created as follows: quiz = pd.Series([78, 85, 62, 90], index=['Asha', 'Ravi', 'Meera', 'Kabir']) (a) Explain how Python decides which element the expression quiz[1] returns, even though 1 is not an index label of this Series. [1] (b) Write the statement that returns the value 62 using its index label. [1]
   Show answer and step marks

   1. (a) The integer 1 is read as a position counted from 0 (zero-based), so quiz[1] selects the second element of the Series, whose value is 85.+1
   2. (b) quiz['Meera'] returns 62, since 'Meera' is the index label of that element.+1

   Answer: (a) An integer in square brackets is treated as a zero-based position, so quiz[1] returns 85, the second element. (b) quiz['Meera']
4. Q4Short answer·3 marks
   The library's stock is stored in a DataFrame named stock, with row labels B1 to B4 and columns Title, Copies and Price, as shown below.

   Label	Title	Copies	Price
   B1	Physics Vol 1	4	450
   B2	Algebra Guide	2	320
   B3	English Grammar	6	275
   B4	World Atlas	3	610

   Write the Python statement for each of the following. (a) Display the number of copies of the book whose row label is 'B3'. [1] (b) Display the Title and Price of the books whose row labels are 'B2' and 'B4', using the row labels. [1] (c) Display the Price of the book in the 4th row, using its position in the DataFrame. [1]
   Show answer and step marks

   1. (a) Uses the row label 'B3' and column label 'Copies' with stock.loc, giving 6.+1
   2. (b) Uses the row labels ['B2', 'B4'] and column labels ['Title', 'Price'] with stock.loc, giving the Title and Price of those two rows.+1
   3. (c) Uses stock.iloc[3, 2] to select row position 3 (4th row) and column position 2 (Price), giving 610.+1

   Answer: (a) stock.loc['B3', 'Copies'] gives 6 (b) stock.loc[['B2', 'B4'], ['Title', 'Price']] gives Algebra Guide 320 and World Atlas 610 (c) stock.iloc[3, 2] gives 610
5. Q5Short answer·3 marks
   A clinic records the details of three admitted patients in the dictionary d given below. The pandas library has been imported as pd. d = {'Name': ['Asha', 'Ravi', 'Meena'], 'Age': [34, 58, 27], 'Ward': ['A1', 'B2', 'A1']} (a) Write the statement to create a DataFrame named clinic from d, so that the rows get the default index 0, 1 and 2. [1] (b) Write the statement to create a DataFrame named clinic2 from d, so that the row labels are 'P101', 'P102' and 'P103'. [2]
   Show answer and step marks

   1. (a) Creates the DataFrame from the dictionary with clinic = pd.DataFrame(d), giving default row labels 0, 1, 2.+1
   2. (b) Passes the dictionary d as the data of pd.DataFrame(d) for clinic2.+1
   3. (b) Sets index=['P101', 'P102', 'P103'] so that these are the row labels.+1

   Answer: (a) clinic = pd.DataFrame(d) (b) clinic2 = pd.DataFrame(d, index=['P101', 'P102', 'P103'])

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