Lab 23 - Write a File-processing Script

For this lab, you will write a script that processes files.

The script iterates through each word in the specified file. If the word matches a known emoji, the word is replaced with that emoji.

A file containing known words and their corresponding emojis should be provided by the user.

Requirements

• The script should be named add_emojis.py
• Require an option named --file that takes a file to be processed
  • The text will be read from this file
• Require an option named --output that specifies the output file
  • The processed text will be written to this file
• Require an option named --emojis that takes a file containing word: emoji pairs
  • The emoji file should be in .json format. See an example below.
• The casing of each word should be ignored, but if the word is not replaced with an emoji, the original word should be printed.
  • i.e. “Dog”, “DOG”, and “dog” should all match “dog”.

Example of a required argument

An argument is required if you specify required=True.

import argparse
parser = argparse.ArgumentParser()
parser.add_argument(
    "--emojis",
    type=str,
    help="The emoji mapping file (json format)",
    required=True
    )
args = parser.parse_args()

If the argument isn’t required you should add a default. Otherwise the value will be None.

import argparse
parser = argparse.ArgumentParser()
parser.add_argument(
    "--emojis",
    type=str,
    default="emojis.json",
    help="The emoji mapping file (json format)"
    )
args = parser.parse_args()

Example emoji file

{
  "dog": "🐶",
  "cat": "🐱",
  "bird": "🐦"
}

How to load a json file in python

import json
filename = "emojis.json"
with open(filename) as file:
    data = json.load(file)
print(data)

Edge cases to watch out for

• Make sure you only replace a word if the whole word matches.
  • If you were using the example emoji file above, you shouldn’t turn “birds” into “🐦s” or “scatter” into “s🐱ter”

Extra Practice

If you finish the above requirements and would like more practice, take a stab at the following features, or add some of your own!

Just be sure to copy add_emojis.py to more_emojis.py before adding more features.

Turn in both add_emojis.py and more_emojis.py

• Handle punctuation

  • If a word ends with punctuation, process only the alphanumeric part at the beginning.
  • e.g. For the example emoji mapping above, “I have a bird.” will become “I have a 🐦.”

• Support an option named --word that indicates which word should be substituted

  • If --word is specified, only the value for that option will be replaced.
  • If the specified word is not in the emojis file, the program should not crash, and the output file should still be written as expected.
  • If --word is not specified, ALL the emojis should be processed.

• Support an option named --extra that takes a string of the format word:emoji (e.g “banana:🍌”).

  • Parse the word and emoji from this option and include them in the emoji dictionary when processing the file.

• Support as many isntances of --extra as the user wants.

  • e.g. --extra "banana:🍌" --extra "bananas:🍌🍌" --extra "duck:🦆"
  • Use add_argument("--extra", ..., action="append") to support multiple instances of that argument

• Make the --output argument optional

  • If --output is not specified, print the processed results to STDOUT

Lessons

What we want you to get from this lab:

• You understand how write an entire Python program from scratch

• You can figure out what went wrong when something unexpected happens

• Hopefully you had fun!

Points

Turn in add_emojis.py and (optionally) more_emojis.py (even if you implement only some of it).