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Занятие 4. Lines

Difficulty level:

Task«Text analysis»

you write an important essay for the school, and your teacher constantly makes you a remark that you too often use the same "parasitic words" (for example: "just", "very", "as if"). You decided to write a program that will help you quickly check your text for the frequency of use of a certain word.

the program must first request a full text of the essay (in the form of one line), and then the word you want to calculate. The program should be insensitive to the register (that is, the word and “word” & mdash; this is one and the same) and ignore the punctuation marks standing close to the word (points, commas, interrogative and exclamation signs). 14pt; "> Your task & mdash; Write a program that accepts the text and the desired word, and then displays how many times this word is found in the text.

& nbsp;

Input format

Output format

The number of entries of the desired word in the text (Integer).

Example

Input

Hello, peace! This is my wonderful world.
World

Output

Hint

methods for working with strings in python

Python provides many built-in methods for working with strings. These are powerful tools that make it easy to manipulate text data. All methods are called with a dot after the variable in which the string is stored, according to the variable scheme.method().

It is important to remember that strings in Python are immutable. This means that none of the methods changes the original string. Instead, they return a new string with the changes applied.

Basic methods for working with strings

1. upper() and lower()

Convert all characters of the string to upper or lower case, respectively.

string = "Hello, World!"
print(string.upper()) # Output: HELLO, WORLD!
print(string.lower()) # Output: hello, world!
print(string) # Output: Hello, World! (the original line has not changed)

A useful tip: These methods are indispensable when you need to compare case-insensitive strings. For example, when checking user input.

user_input = "Yes"
if user_input.lower() =="yes":
print("The user agrees.")

2. strip(), lstrip() and rstrip()

Remove whitespace characters (spaces, tabs, line breaks) from the beginning and end of the line. lstrip() deletes only on the left, and rstrip() deletes only on the right.

string = "  Hello, World!  "
print(string.strip()) # Output: Hello, World!
print(string.lstrip()) # Output: Hello, World!  
print(string.rstrip()) # Output: Hello, World!

A useful tip: These are extremely important methods for "cleaning" data obtained from files or from users, who often accidentally leave unnecessary spaces. As an argument, you can pass a string of characters that need to be deleted.

dirty_string = "!!!Hello, World!?! "
print(dirty_string.strip(" !?")) # Output: Hello, World

3. split() and join()

split() splits a string into a list of substrings using the specified separator. join() collects a string from the list items by inserting a separator string between them.

string = "Hello, World!"
words =string.split(", ")
print(words) # Output: ['Hello', 'World!']

# Reverse operation
joined_string = " | ".join(words)
print(joined_string) # Output: Hello | World!

A useful tip: split() is a standard method for parsing (parsing) data presented as a string, for example, CSV files. join() is the most efficient ("pythonic") way to assemble one large string from many small ones. It works much faster than adding strings in a loop using +.

4. find() and replace()

find() searches for the first occurrence of a substring and returns its index (position). If the substring is not found, returns -1. replace() replaces all occurrences of one substring with another.

string = "Hello, World!"
index = string.find("World")
print(index) # Output: 7

new_string = string.replace("World", "Python")
print(new_string) # Output: Hello, Python!

A useful tip: There is an analog of the find() index() method.. It does the same thing, but if the substring is not found, it raises the error ValueError. Use find() if the absence of a substring is a normal situation, and index(), if it should interrupt the execution of the program. The replace() method can also accept a third argument - the number of substitutions to be made.

5. startswith() and endswith()

They check whether the string begins or ends with a specific substring. Returns True or False.

string = "Hello, World!"
print(string.startswith("Hello")) # Output: True
print(string.endswith("World!"))   # Output: True
print(string.startswith("Bye"))    # Output: False

A useful tip: It is very convenient for quick checking of file formats (filename.endswith(".txt")) or link types (url.startswith("https")).

6. isdigit(), isalpha() and isalnum()

They check what the string consists of.

isdigit(): True if all characters are numbers.
isalpha(): True if all characters are letters.
isalnum(): True if all characters are letters or numbers.

string1 = "12345"
string2 = "Hello"
string3 = "Hello123"

print(f"'{string1}' consists of digits? {string1.isdigit()}")   # Output: True
print(f"'{string2}' consists of letters? {string2.isalpha()}")   # Output: True
print(f"'{string3}' consists of letters and numbers? {string3.isalnum()}") # Output: True
print(f"'{string2}' consists of digits? {string2.isdigit()}") # Output: False

A useful tip: These methods are ideal for validating user input before attempting to convert a string to a number or using it further in the program.

A complete guide to methods

Below is a table with a more complete list of string methods for quick reference.

Method	Purpose
`S.find(str, [start],[end])`	Search for a substring in a string. Returns the number of the first occurrence or -1.
`S.rfind(str, [start],[end])`	Search for a substring in a string. Returns the number of the last occurrence or -1.
`S.index(str, [start],[end])`	Search for a substring in a string. Returns the number of the first occurrence or causes a `ValueError`.
`S.rindex(str, [start],[end])`	Search for a substring in a string. Returns the number of the last occurrence or causes a `ValueError`.
`S.replace(template, replacement[, maxcount])`	Replace the template with a replacement. `maxcount` limits the number of substitutions.
`S.split(character)`	Splitting a line by separator.
`S.isdigit()`	Whether the string consists of numbers.
`S.isalpha()`	Whether the string consists of letters.
`S.isalnum()`	Whether the string consists of numbers or letters.
`S.islower()`	Whether the string consists of lowercase characters.
`S.isupper()`	Whether the string consists of uppercase characters.
`S.isspace()`	Whether the string consists of non-displayed characters (space, `\f`, `\n`, `\r`, `\t`, `\v`).
`S.istitle()`	Whether words in a line begin with a capital letter.
`S.upper()`	Converting a string to uppercase.
`S.lower()`	Converting a string to lowercase.
`S.startswith(str)`	Does the string S start with the template `str`.
`S.endswith(str)`	Does line S end with the `str` template.
`S.join(list)`	Assembling a line from a list separated by S.
`ord(character)`	Converts a character to its ASCII/Unicode code.
`chr(number)`	Converts the ASCII/Unicode code to a character.
`S.capitalize()`	Converts the first character of the string to uppercase, and all the others to lowercase.
`S.center(width, [fill])`	Returns a centered string with the `fill` character at the edges (space by default).
`S.count(str, [start],[end])`	Returns the number of disjoint occurrences of a substring.
`S.expandtabs([tabsize])`	Replaces the tab characters `\t` with spaces.
`S.lstrip([chars])`	Deleting specified characters (or spaces) at the beginning of a line.
`S.rstrip([chars])`	Deleting specified characters (or spaces) at the end of a line.
`S.strip([chars])`	Deleting specified characters (or spaces) at the beginning and end of a line.
`S.partition(template)`	Divides a string by the first occurrence of the separator into three parts: before, the separator itself, and after.
`S.rpartition(sep)`	Divides the string by the last occurrence of the separator into three parts: before, the separator itself, and after.
`S.swapcase()`	Converts lowercase characters to uppercase, and uppercase characters to lowercase.
`S.title()`	Translates the first letter of each word to uppercase, and all the others to lowercase.
`S.zfill(width)`	Adds zeros to the left of the string to the length `width`.
`S.ljust(width, fillchar=" ")`	Aligns the line to the left, adding the characters `fillchar` to the right.
`S.rjust(width, fillchar=" ")`	Aligns the line to the right, adding `fillchar` characters to the left.
`S.format(args, *kwargs)`	String formatting (a more modern alternative to `%`).

main.py

Test 1

Test 2

Test 3

Test 4

Test 5

Test 6

Test 7

Test 8

Test 9

Test 10

Developer’s solution

# Получаем от пользователя строку с текстом для анализа
text = input()
# Получаем от пользователя слово, которое нужно найти
search_word = input()

# Приводим весь текст к нижнему регистру для нечувствительного к регистру сравнения
text_lower = text.lower()
# Приводим искомое слово к нижнему регистру
search_word_lower = search_word.lower()

# Убираем основные знаки препинания из текста, заменяя их на пустую строку
text_cleaned = text_lower.replace('.', '').replace(',', '').replace('!', '').replace('?', '')

# Разделяем обработанный текст на отдельные слова по пробелам
words = text_cleaned.split()

# Создаем переменную-счетчик для подсчета вхождений
count = 0

# Запускаем цикл, который перебирает каждое слово в списке words
for word in words:
  # Проверяем, совпадает ли текущее слово из списка с искомым словом
  if word == search_word_lower:
    # Если слова совпадают, увеличиваем счетчик на 1
    count = count + 1

# Выводим итоговое значение счетчика
print(count)

🎉 Congratulations! 🎉

You did an excellent job with the task! It was a challenging problem, but you found the correct solution. You are one step closer to mastering programming! Keep up the good work, because every stage you pass makes you even stronger.