Python

Dictionaries are Python’s implementation of an associative list, which is a data structure. A dictionary is a collection of key-value pairs that are stored together. A key and its value are represented by each key-value pair.

Given a dictionary, the task is to print all the values of the dictionary.

Examples:

Input:

dictionary = {'this': 200, 'is': 100, 'BTechGeeks': 300}

Output:

200
100
300

Display all values of the Dictionary

There are several ways to display all the values of the dictionary some of them are:

• Using for loop and values() function
• Converting values to list
• Using list Comprehension

Method #1:Using for loop and values() function

The dictionary class in Python has a function dict.values() that returns an iterable sequence of dictionary values. We can iterate over the sequence of values returned by the function values() using a for loop, and we can print each value while iterating.

Below is the implementation:

# Given dictionary
dictionary = {'this': 200, 'is': 100, 'BTechGeeks': 300}
# Traverse the dictionary using for loop
for value in dictionary.values():
    # print the values
    print(value)

Output:

200
100
300

Method #2:Converting values to list

The sequence returned by the values() function can be passed to the list to create a list of all values in the dictionary .

We use list() function to achieve this. Print the list(values)

Below is the implementation:

# Given dictionary
dictionary = {'this': 200, 'is': 100, 'BTechGeeks': 300}
# converting values to list
valueslist = list(dictionary.values())
# print the values list
for value in valueslist:
    print(value)

Output:

200
100
300

Method #3:Using  list Comprehension

We can also use this list comprehension to iterate through all of the dictionary’s values and print each one individually.

Below is the implementation:

# Given dictionary
dictionary = {'this': 200, 'is': 100, 'BTechGeeks': 300}
# using list comprehension
print([value for value in dictionary.values()])

Output:

[200, 100, 300]

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A collection is an ordered list of values. There could be various types of values. A list is a mutable container. This means that existing ones can be added to, deleted from, or changed.

The Python list represents the mathematical concept of a finite sequence. List values are referred to as list items or list elements. The same value may appear multiple times in a list. Each event is regarded as a distinct element.

Example:

Input:

givenlist = ['BTechGeeks', 'BTechGeeks', 'BTechGeeks', 'BTechGeeks', 'BTechGeeks', ]

Output:

All the elements are equal

Given a list, the task is to check if all elements in a list are same or matches the given condition

Check that all items in a list are identical

There are several ways to check if all elements in a list are same or matches a condition some of them are:

• Using all() function
• Using set()
• Using count() function

Method #1:Using all() function

any():

If any of the items is True, this function returns True. If the array is empty or all of the values are false, it returns False. Any can be thought of as a series of OR operations on the iterables provided.

Let’s convert the list to Iterable and check that each iterable entry is the same as the first list element using all ()

Below is the implementation:

# given list
givenlist = ['BTechGeeks', 'BTechGeeks',
             'BTechGeeks', 'BTechGeeks', 'BTechGeeks', ]
# checking if all the elements are equal using all() function
if(any(element == givenlist[0] for element in givenlist)):
    print("All the elements are equal")
else:
    print("All the elements are not equal")

Output:

All the elements are equal

Method #2:Using set()

• Set includes only single elements.
• Convert the list to set and check whether the length of the set is 1.
• If the length of given set is 1 the print all the elements are equal
• else print all the elements are not equal

Below is the implementation:

# given list
givenlist = ['BTechGeeks', 'BTechGeeks',
             'BTechGeeks', 'BTechGeeks', 'BTechGeeks', ]
# converting given list to set
setlist = set(givenlist)
# if the length of given set is 1 then print all the elements are equal
if(len(setlist) == 1):
    print("All the elements are equal")
else:
    print("All the elements are not equal")

Output:

All the elements are equal

Method #3:Using count() function

Count() returns to the list the number of times the item is appeared.

Let’s call the list’s count() function with the first element as an argument. If the number of times it appears in the list equals the length of the list, it means that all of the elements in the list are the same.

Below is the implementation:

# given list
givenlist = ['BTechGeeks', 'BTechGeeks',
             'BTechGeeks', 'BTechGeeks', 'BTechGeeks', ]
# using count function
if(givenlist.count(givenlist[0]) == len(givenlist)):
    print("All the elements are equal")
else:
    print("All the elements are not equal")

Output:

All the elements are equal

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Dictionaries are the implementation by Python of a data structure associative array. A dictionary is a collection of pairs of key values. A key pair and its associated value represent each key pair.

The list of key value pairs in curly braces that is separated by comma defines a dictionary. Column ‘:’ separates the value of each key.

A dictionary cannot be sorted only to get a representation of the sorted dictionary. Inherently, dictionaries are orderless, but not other types, including lists and tuples. Therefore, you need an ordered data type, which is a list—probably a list of tuples.

Given a dictionary, the task is to convert values of this dictionary to a list.

Examples:

Example 1:

Input:

dictionary = {'this': 200, 'is': 100, 'BTechGeeks': 300}

Output:

[200, 100, 300]

Example 2:

Input:

dictionary = {'this': 200, 'is': 100, 'BTechGeeks': 300 ,'python' :400}

Output:

[200, 100, 300,400]

Convert Dictionary Values to a List in Python

There are several ways to convert dictionary values to a list some of them are:

• Using list() function
• Using List Comprehension
• Convert specific values of dictionary to list

Method #1:Using list() function

A dictionary class in Python has a function values() that returns an iterable sequence of all dictionary values. The list() function will return a list containing all of the dictionary’s values if we transfer this iterable sequence(dict values) to it.

Below is the implementation:

# Given dictionary
dictionary = {'this': 200, 'is': 100, 'BTechGeeks': 300}
# converting values to list
valueslist = list(dictionary.values())
# print the values list
for value in valueslist:
    print(value)

Output:

[200, 100, 300]

Method #2:Using List Comprehension

We can also use this list comprehension to iterate over the values of dictionary and convert to list.

Below is the implementation:

# Given dictionary
dictionary = {'this': 200, 'is': 100, 'BTechGeeks': 300}
# converting values to list using list comprehension
valueslist = ([value for value in dictionary.values()])
# print the values list
print(valueslist)

Output:

[200, 100, 300]

Method #3:Convert specific values of dictionary to list

Assume we want to convert only a selected values in a dictionary to a list.

As an example, consider converting values greater than 100.

We can accomplish this by iterating through the dictionary values and checking the condition.

Below is the implementation:

# Given dictionary
dictionary = {'this': 200, 'is': 100, 'BTechGeeks': 300}
# Traverse the dictionary values and check condition
valueslist = [value for value in dictionary.values() if value > 100]
# print the values list
print(valueslist)

Output:

[200, 300]

 
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To manage looping specifications, the Python programming language contains the following types of loops. The loops can be executed in three different ways in Python. Although all of the methods have similar basic features, they vary in syntax and the time it takes to search for conditions.

For loops:

In Python, the for loop is used to iterate over a list, tuple, or string, or other iterable properties. Traversal is the process of iterating over a sequence.

While loops:

While Loops are used in Python to execute a set of statements over and over until a condition is met.. When the condition is met, the line immediately following the loop in the programme is executed. Indefinite iteration is demonstrated by the while loop. The term “indefinite iteration” refers to the fact that the number of times the loop is executed is not specified explicitly in advance.

Continue keyword in Python Loops

• Continue keyword
• Continue keyword in While loop
• Continue keyword in For loop

1)Continue keyword

In Python, loops are used to simplify and repeat tasks in an effective manner. However, there can be occasions when you want to completely exit the loop, miss an iteration, or ignore the condition. Loop control statements can be used to do this. Control statements in loops alter the execution sequence.

Like the break comment, continue is a loop control statement. The continue statement is the polar opposite of the break statement in that it pushes the loop to perform the next iteration rather than ending it.
The continue argument, as its name implies, forces the loop to continue or perform the next iteration. When the continue statement is used in a loop, the code within the loop that follows the continue statement is skipped, and the loop’s next iteration begins.

2)Continue keyword in While loop

The control will jump back to the beginning of the while loop if the continue keyword is used within the loop. For that iteration, all lines following the continue keyword will be skipped.

Consider the following scenario: we want to print all numbers from 1 to n that are not divisible by 5.

Below is the implementation:

# given n
n = 16
# let us take a temp variable to 0 as we need to print all numbers from 1 to n
temp = 0
while(temp < n):
    # increment the temp
    temp += 1
    # if the temp is divisible by 5 then use continue
    # As a result, the number will not be printed.
    if(temp % 5 == 0):
        continue
    else:
        print(temp)

Output:

1
2
3
4
6
7
8
9
11
12
13
14
16

Explanation:

We are printing numbers from 1 to n in this while loop. However, within the loop body, we have a check that says if temp is divisible by 5 we should execute the continue keyword.

As a result, when the value of temp is divisible by 5, the continue statement is executed. It returns control to the beginning of the loop and skips the print statement at the end of the loop body.

3)Continue keyword in For loop

Let the implement the above code using for loop.

Below is the implementation:

# given n
n = 16
# using for loop
for temp in range(1, n+1):
    # if the temp is divisible by 5 then use continue keyword
    # As a result, the number will not be printed.
    if temp % 5 == 0:
        continue
    else:
        print(temp)

Output:

1
2
3
4
6
7
8
9
11
12
13
14
16

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A Python string is a collection of characters surrounded by single, double, or triple quotes. The computer does not understand the characters; instead, it stores the manipulated character as a combination of 0’s and 1’s internally.

In this article we are going to discuss the use of upper() function.

String upper() Method in Python

• Upper() function
• Converting a string to uppercase
• Converting the string which has numbers and letters to uppercase
• Convert two strings to uppercase and compare them
• Convert character to uppercase

1)Upper() function

The string upper() method returns a string that has all lowercase characters converted to uppercase characters.

Syntax:

given_string.upper()

Parameters:

The upper() method does not accept any parameters.

Return:

The upper() method returns the uppercased version of the given string. All lowercase characters are converted to uppercase.

If no lowercase characters are found, the original string is returned.

2)Converting a string to uppercase

We can convert it using built in function upper().

Below is the implementation:

# given string
string = "btech geeks"
# converting string to upper
string = string.upper()
# print the string
print(string)

Output:

BTECH GEEKS

Explanation:

It returned a copy of the given string, and all lowercase characters were converted to uppercase characters in the returned copy. The uppercase copy of the string was then assigned to the original string.

3)Converting the string which has numbers and letters to uppercase

As the above method we can convert it to uppercase using upper() function.

Below is the implementation:

# given string
string = "btech 2021 geeks"
# converting string to upper
string = string.upper()
# print the string
print(string)

Output:

BTECH 2021 GEEKS

4)Convert two strings to uppercase and compare them

We can convert the given two strings to upper() function and we can compare them using “=” operator.

Below is the implementation:

# given string
string1 = "BTechGeeks"
string2 = "btechgeeks"
# converting both strings to uppercase using upper() function
string1 = string1.lower()
string2 = string2.lower()
# compare the two strings
if(string1 == string2):
    print("Both strings are equal")
else:
    print("Both strings are not equal")

Output:

Both strings are equal

5)Convert character to uppercase

We can convert it using built in function upper().

Below is the implementation:

# given character
character = 'b'
# convert to uppercase using upper() function
character = character.upper()
# print the character
print(character)

Output:

B

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A collection is an ordered list of values. There could be various types of values. A list is a mutable container. This means that existing ones can be added to, deleted from, or changed.

The Python list represents the mathematical concept of a finite sequence. List values are referred to as list items or list elements. The same value may appear multiple times in a list. Each event is regarded as a distinct element.

Example:

Input:

givenlist = ['hello', 'this', 'is', 'hello', 'BTechGeeks', 'is', 'this']

Output:

Given list with duplicates :  ['hello', 'this', 'is', 'hello', 'BTechGeeks', 'is', 'this']
Given list without duplicates :  ['hello', 'this', 'is', 'BTechGeeks']

Delete Duplicates elements from the list

We can delete duplicate elements by many methods some of them are:

• Using set
• Using in operator and lists (same order)
• Using Counter() function (same order)

Method #1:Using set

• A set is an unordered data structure with only unique elements.
• So, using the set() function, convert the given list to a set and then back to a list.
• Print the list

Below is the implementation:

# given list (which contains duplicates)
givenlist = ['hello', 'this', 'is', 'hello', 'BTechGeeks', 'is', 'this']
print('Given list with duplicates : ', givenlist)
# converting givenlist to set and then back to list to remove duplicates
givenlist = list(set(givenlist))
# print given list
print('Given list without duplicates : ', givenlist)

Output:

Given list with duplicates :  ['hello', 'this', 'is', 'hello', 'BTechGeeks', 'is', 'this']
Given list without duplicates :  ['this', 'is', 'hello', 'BTechGeeks']

Note:

While this method avoids duplicates, it does not hold the elements in the same order as the original.

Method #2:Using in operator and lists (same order)

For unique elements, we’ll need to make a new list. Then iterate through the original list, adding each element to the newList only if it isn’t already there.

Below is the implementation: 

# given list (which contains duplicates)
givenlist = ['hello', 'this', 'is', 'hello', 'BTechGeeks', 'is', 'this']
print('Given list with duplicates : ', givenlist)
# taking empty list
newlist = []
# Travers the given list
for element in givenlist:
    # if the element is not present in new list then append it
    if element not in newlist:
        newlist.append(element)
# print new list
print('Given list without duplicates : ', newlist)

Output:

Given list with duplicates :  ['hello', 'this', 'is', 'hello', 'BTechGeeks', 'is', 'this']
Given list without duplicates :  ['hello', 'this', 'is', 'BTechGeeks']

Method #3:Using Counter() function (same order)

• Counter() function is mainly used to calculate the frequencies of all elements .
• In this case we calculate the frequencies using Counter function which returns dictionary having unique keys.
• Convert this keys to list and print it.

Below is the implementation:

from collections import Counter
# given list (which contains duplicates)
givenlist = ['hello', 'this', 'is', 'hello', 'BTechGeeks', 'is', 'this']
print('Given list with duplicates : ', givenlist)
# counting the frequencies using Counter function
freq = Counter(givenlist)
# converting keys to list
uniquelist = list(freq.keys())
# print unqiue list
print('Given list without duplicates : ', uniquelist)

Output:

Given list with duplicates :  ['hello', 'this', 'is', 'hello', 'BTechGeeks', 'is', 'this']
Given list without duplicates :  ['hello', 'this', 'is', 'BTechGeeks']

 
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While Loops are used in Python to execute a set of statements over and over until a condition is met.. When the condition is met, the line immediately following the loop in the programme is executed. Indefinite iteration is demonstrated by the while loop. The term “indefinite iteration” refers to the fact that the number of times the loop is executed is not specified explicitly in advance.

While Loop in Python

• Syntax:
• Working of while loop
• Print first n natural numbers
• Multiple conditions in while loop
• While loop with else

1)Syntax:

while expression:
    statement(s)

2)Working of while loop

After a programming construct, all statements indented by the same number of character spaces are considered to be part of a single block of code.. Python’s method of grouping statements is indentation. When a while loop is run, expression is evaluated in a Boolean context and, if true, the loop body is executed. The expression is then checked again, and if it is still true, the body is executed again, and so on until the expression becomes false.

3)Print first n natural numbers

Using while loop to print first n natural numbers. let us take n=15

Below is the implementation: 

# using while loop to print natural numbers upto n
n = 15
# let us take a temp variable to 1 as natural numbers starts from 1
temp = 1
# using while loop
while(temp <= n):
    # printing temp variable
    print(temp)
    # increment the temp by 1
    temp = temp+1

Output:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15

4)Multiple conditions in while loop

In a while statement, we can have multiple conditions, and we can use ‘and’ and ‘or’ with these conditions.

Below is the implementation: 

# using while loop to print even natural numbers upto n
n = 15
# let us take a temp variable to 2 as natural numbers starts from 2
temp = 2
# using while loop
while(temp <= n and temp % 2 == 0):
    # printing temp variable
    print(temp)
    # increment the temp by 2
    temp = temp+2

Output:

2
4
6
8
10
12
14

5)While loop with else

In Python, we can have while…else blocks similar to if…else blocks, i.e., an else block after a while block.

The while loop will execute statements from the white suite multiple times until the condition is evaluated as False. When the condition in the while statement evaluates to False, control moves to the else block, where all of the statements in the else suite are executed.

Ex: Printing first n natural numbers and printing 0 at last.

Below is the implementation: 

# using while loop to print natural numbers upto n
n = 10
# let us take a temp variable to 1 as natural numbers starts from 1
temp = 1
# using while loop
while(temp <= n):
    # printing temp variable
    print(temp)
    # increment the temp by 1
    temp = temp+1
else:
    print(0)

Output:

1
2
3
4
5
6
7
8
9
10
0

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