[Introduction to Python] Summary of functions and methods that frequently appear in Python [Problem format]

Introduction

Python provides a variety of built-in functions and methods. Among them, I have summarized the ones that I use frequently.

Overview

The task of Tommy's blog was very helpful in understanding Python, so I will proceed with this article in the form of a task. If you have any questions, please refer to the detailed explanation at the link.

Target person

This article is for the following people.

• Python installation and Jupyter Notebook environment construction have been completed.
• I touched Python a little.
• I want to check my ability!

environment

• macOS High Sierra 10.13.6
• Python 3.7.6

Implementation details

Exercise 1 Calculate the average amount of input amount

Technical elements

• Use of lists and frequent methods (append)
• Use of functions to calculate lists (sum, len)
• Use function for input (input)
• Use of conditional branching

Outline of specifications

• Enter the participant's money
• Stop the calculation when 0 yen is entered
• Calculate the average value of your money

Output image

Implementation example

#Prepare a list to store input values
money_list = []

#Store average amount
average = 0
while True:
    #Store input value
    money = int(input("Please tell me your money:"))   
    if money == 0:
        break
    #Add the amount entered in the list
    money_list.append(money)

#Consider division by zero
if len(money_list) !=0:
    #Calculate the total value
    s = sum(money_list)
    #The size stored in the list(Here the number of elements)
    n = len(money_list)
    #Calculate the average value
    average = s / n
    
print("The average amount of money that everyone has",average,"is.")

Exercise 2 Count all the characters in English words

Outline of specifications

• Enter English words.
• If nothing is entered, finish typing English words.

Specification details

• Create the list with the following contents.
• Lowercase alphabet (key)
• Numerical value (initial value: 0)
• Decomposes the entered English words.
• Count the number of occurrences of the alphabet you write.
• When the input is completed, the English word list is sorted.
• Sorting is the number of words
• Display the result of the number of occurrences of the alphabet.

Output image

Implementation example

alphabet_code= dict.fromkeys(list("abcdefghijklmnopqrstuvwxyz"), 0)
words = []

#Enter English words and add the number of characters
while True:
    word = input("Please enter and specify English words:")
    if word == "":
        break
    words.append(word)
    for letter in word:
        if letter in alphabet_code.keys():
            #Add if you have a key(If not judged, key error will occur)
            alphabet_code[letter] += 1

print('')
print('The words entered are:')
words.sort()
for word in words:
    print('・' + word)

print('')
print('The result of the number of alphabet appearances is as follows')
for letter , count in alphabet_code.items():
    print("{0}\Number of occurrences of t: {1}Times".format(letter, count))

Exercise 3 Output the result of the specified Fibonacci sequence

Technical elements

• Use of functions
• Understanding recursive functions

Outline of specifications

• Display input message and input form
• Message: "Which number in the Fibonacci sequence do you represent?"
• Display the Favonatch sequence with the entered number

Usage details

• Create a Fibonacci sequence function
• The first and second numbers are 1
• The third and subsequent numbers are the sum of the previous number and the second previous number.
• Recursive call using while statement

Output image

Implementation example

def fib_func(n):
    if n == 0:
        return 0
    elif n == 1:
        return 1
    else:
        return fib_func(n - 1) + fib_func(n - 2)

target_num = int(input('What number in the Fibonacci sequence do you represent?: ') )
print(fib_func(target_num))

Reference information

This article is based on Tommy's blog Roadmap article. If you want to know more details or other ways to use it, we recommend learning from the link. Not only the tasks but also the know-how for learning Python from scratch is open to the public, so please take advantage of it!