 Computer Science

# Homework 4f — Random and coiteration

## 1. Random asterisks

Write a function named `random_asterisks()` that takes two arguments:

• a text (string)
• a frequency (float)

This function uses the frequency to “roll the dice” for each word in the text and randomly determine whether it will replace the word with an asterisk (`*`). For example, if we call this function with:

``random_asterisks("my dog has fleas", 0.5)``

This means there is a `50%` chance that any given word will be replaced with an asterisk. The word “my” has a `50%` chance of being replaced with `*`, the word “dog” has a `50%` chance of being replaced with `*`, the word “has” has a `50%` chance of being replaced with `*`, and so forth.

Since the function uses random numbers, every time you call it you may get a different result. Here are some examples of what could happen:

``````# 50% chance that a word is changed to an asterisk
random_asterisks("my dog has fleas", 0.5)
'* dog has *'

# 100% chance that a word is changed to an asterisk
random_asterisks("my dog has fleas", 1)
'* * * *'

# 0% chance that a word is changed to an asterisk
random_asterisks("my dog has fleas", 0)
'my dog has fleas'

# 50% chance that a word is changed to an asterisk
random_asterisks("1 2 3 11 12 13 14 15 16 100 101", 0.5)
'1 * 3 11 12 * * 15 16 * *'``````

Hints

You will need a line of code that is true or false with a certain chance. Example code can be found in the Random Float section in the guide on random.

The pytest only runs your `random_asterisks` function. You do not need to use system arguments. You can write a main block to test your `random_asterisks` function yourself:

``````if __name__ == '__main__':
random_asterisks("my dog has fleas", 0.5)``````

You might try the examples from above as your text and frequency.

## 2. Compare strings

Write a program named `compare_strings.py` that prompts the user for two words. Then compare the words character-by-character and print the result.

• If the pair of characters match, output a `*`
• If the pair does not match, output a `.`

The user enters an empty string for word 1 to end the program.

``````python compare_strings.py
Word 1: when
Word 2: what
**..
Word 1: tacos
Word 2: catch
.*...
Word 1:``````

Note

You will want to write you own main block, such as:

``````def main():
# Write code here

if __name__ == '__main__':
main()``````

## 3. Word guess

Write a program named `word_guess.py` that takes a file as an argument. This file should contain a sequence of words, one word per line.

The program then randomly chooses a word from this file for the user to guess. The user guesses a word:

• if the guess matches the secret word, print “That’s it!”
• otherwise, if the guess is a substring of the secret word, print “almost”
• otherwise, if any of the letters in the guess can be found in the secret word, print “close”
• otherwise print “nope”

The file `word_list.txt` contains an example file to use for input:

`word_list.txt`

``````cat
dog
fish``````

Following is an example of how you might run the program:

``````% python word_guess.py word_list.txt
Guess a word: dog
nope
Guess a word: ball
close
Guess a word: at
almost
Guess a word: cat
That's it!``````

Following is an example of how you might run the program:

``````% python word_guess.py word_list.txt
Guess a word: fish
nope
Guess a word: cat
nope
Guess a word: done
close
Guess a word: do
almost
Guess a word: dog
That's it!``````

Tips

When reading in lines from a file, each line will end with a newline character `\n`. You may find it useful to remove this character using strip. For example:

``line = line.strip()``

This will remove any whitespace from the start and end of line, including the newline character.

For the “close” option, the best thing is to make a new function that takes two words.

``````def any_char_in_word(word1: str, word2: str) -> bool:
# Write code here``````

This function could iterate through each character in the first word, and return True if the character is in the second word. It should return False if there are no characters in the first word that are in the second word. You do not need to use zip.

## Tests

Be sure you can pass the tests before you turn in the assignment. Review the guide on using pytest if you need to review using pytest and what to do if a test fails.