Informatics Practices

The data type list is an ordered sequence which is mutable and made up of one or more elements. Unlike a string which consists of only characters, a list can have elements of different data types such as integer, float, string, tuple or even another list. A list is very useful to group elements of mixed data types. Elements of a list are enclosed in square brackets and are separated by comma.
(i) How is a list different from a dictionary?
(ii) Find the values of y and z after execution:

x=[2, 3]
y=[30, 40]
z=[88, 99]
y.extend(x)
z.append(x)
print (y)
print (z)

Python List Manipulation

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Answer

(i) A list in Python is an ordered collection of elements that can be accessed by their index. In contrast, a dictionary is an unordered collection of key-value pairs, where values are accessed using unique keys. Elements of a list are enclosed in square brackets and are separated by comma while dictionaries are enclosed in curly brackets, with keys and values separated by colons and key-value pairs separated by commas.

(ii)

Output

[30, 40, 2, 3]
[88, 99, [2, 3]]

Explanation

y.extend(x) modifies the list y by adding the elements of x to the end of y. So, y becomes [30, 40, 2, 3].
z.append(x) adds the entire list x as a single element to the end of z. So, z becomes [88, 99, [2, 3]].

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Write the output for the following print statements in Python.

Sub_Teacher = {"English":"Mr. Gill", "Maths": "Mr. R.N. Pandey", "IP":"Ms. Renu Ahuja", "Physics": "Ms. Meenu Lal", "Chemistry":"Ms. Mamta Goel"}
print(Sub_Teacher['Chemistry'])  #Line1
print(Sub_Teacher.keys())       #Line2
print(len(Sub_Teacher))        #Line3

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