Python - Project - Flash Card (Day 31)

This is a 100 Days challenge to learn a new language (Python). 100 Days of Code - The Complete Python Pro Bootcamp 

I will post some notes to motivate myself to finish this challenge.

Goal

1. Using Tkinter to build a GUI

a. Using canvas to mix images and texts

b. Binding functions to buttons

c. Utilizing grid layout for the better look

d. Lean how to update Tkinter elements

2. Deal with csv file through pandas

a. Support reading and writting

b. Studying some parameters when transform DataFrame to other DataType

DataFrame.to_dict(orient="records")

3. Using after and after_cancel to manage events

4. Try to use Error Handling as we learned on Day 30

Requirements

1. Build a flash card app which read data from csv file.

2. After 3 seconds, app should flip the card to see the translated word.

3. Next word should be shown after both buttons got clicked.

4. Once users click 'mark' button (or I knew button), then we should not let users see this word anymore.

5. Save the progress to csv file and read data from it from the next play.

Project - Flash Card

Ex:

import tkinter as tk

import pandas as pd

import random

import os

BACKGROUND_COLOR = "#B1DDC6"

FONT = "Ariel"

ALL_WORDS_CSV_FILE = "data/1000 words (en-to-zh-tw).csv"

WORDS_TO_LEARN_CSV_FILE = "data/words_to_learn.csv"

# Variables

words_dic = {}

selected_word = {}

filp_timer = ""

# Read a comma-separated values (csv) file into DataFrame.

# NOTE:

# Using Exception handling here for practice only becuse it is easy

# to be abused

# It is better to find a proper way

# (such as adding some if-else condition)

try:

    words_to_learn_data_frame = pd.read_csv(WORDS_TO_LEARN_CSV_FILE)

except FileNotFoundError:

    # If we cannot find the historical data,

     # then we read data from raw csv

    all_words_data_frame = pd.read_csv(ALL_WORDS_CSV_FILE)

    words_dic = all_words_data_frame.to_dict(orient="records")

else:

    words_dic = words_to_learn_data_frame.to_dict(orient="records")

def game_over():

    """Show game over message, and remvoe the historical data"""

    # Clear title and word text

    canvas.delete(title_text)

    canvas.delete(word_text)

    # Add game over message

    canvas.create_text(

        400,

        170,

        text="You have learned all words",

        fill="black",

        font=(FONT, 40, "bold"),

    )

    # Remove 'words_to_learn.csv'

    if os.path.exists(WORDS_TO_LEARN_CSV_FILE):

        os.remove(WORDS_TO_LEARN_CSV_FILE)

def right_btn_clicked():

    """Need to remove the current word from the list and

dump the updated list to csv file, then generate the next word"""

    # Remove the previous word since users knew it

    global selected_word

    if selected_word:

        words_dic.remove(selected_word)

        # Reset it

        selected_word = {}

    # Export current words collection to csv

    words_to_learn_data_frame = pd.DataFrame.from_dict(words_dic)

    words_to_learn_data_frame.to_csv(

"data/words_to_learn.csv",

index=False

)

    next_word()

def next_word():

    """Randomly select a word and show it in card"""

    # cancel previous timer if needed

    global filp_timer

    if not filp_timer == "":

        root.after_cancel(filp_timer)

    # Game Over - No more words to learn

    if len(words_dic) == 0:

        game_over()

        return

    # Change the canvas image to front_image

    canvas.itemconfig(canvas_image, image=front_image)

    # Randomly select a word and save it to the

# global variable selected_word

    global selected_word

    selected_word = random.choice(words_dic)

    # Change title and word

    canvas.itemconfig(title_text, fill="black", text="English")

    canvas.itemconfig(word_text, fill="black",

text=selected_word.get("English"))

    # Update global variable filter_timer

    filp_timer = root.after(3000, flip_card)

def flip_card():

    """Show Chinese Word"""

    # Change the canvas image to back_image

    canvas.itemconfig(canvas_image, image=back_image)

    # Change title and word

    canvas.itemconfig(title_text, fill="white", text="Chinese")

    canvas.itemconfig(

        word_text, fill="white",

text=selected_word.get("Traditional Chinese")

    )

# Init Tkinter

root = tk.Tk()

root.title("Flash Card")

root.config(padx=50, pady=50, background=BACKGROUND_COLOR)

# Init canvas

canvas = tk.Canvas(

    width=800, height=526, background=BACKGROUND_COLOR,

highlightthickness=0

)

# Add card_front image and set it to the center of the canvas

front_image = tk.PhotoImage(file="images/card_front.png")

back_image = tk.PhotoImage(file="images/card_back.png")

canvas_image = canvas.create_image(400, 263, image=front_image)

# Add Title Text, and set it to the middle and a bit up of the canvas

title_text = canvas.create_text(

    400, 150, text="", fill="black", font=(FONT, 40, "italic")

)

# Add Word Text, and set it to the middle and a bit down of the canvas

word_text = canvas.create_text(400, 253, text="", fill="black",

font=(FONT, 60, "bold"))

canvas.grid(column=0, row=0, columnspan=2)

# Wrong Btn

wrong_image = tk.PhotoImage(file="images/wrong.png")

wrong_btn = tk.Button(image=wrong_image, command=next_word)

wrong_btn.config(background=BACKGROUND_COLOR,

activebackground=BACKGROUND_COLOR)

wrong_btn.grid(sticky="ew", column=0, row=1)

# Right Btn

right_image = tk.PhotoImage(file="images/right.png")

right_btn = tk.Button(image=right_image, command=right_btn_clicked)

right_btn.config(background=BACKGROUND_COLOR,

activebackground=BACKGROUND_COLOR)

right_btn.grid(sticky="ew", column=1, row=1)

# Get the first Word Card

next_word()

# Start the Event Loop

root.mainloop()

Python - Exceptions and JSON (Day 30)

This is a 100 Days challenge to learn a new language (Python). 100 Days of Code - The Complete Python Pro Bootcamp 

I will post some notes to motivate myself to finish this challenge.

Exceptions

When exceptions occur, python program will stop and show some error messages.

There are some normal exceptions below.

FileNotFound

Ex: 

with open("no_such_file.txt") as file:

    print(file.read())

Result:

FileNotFoundError:

[Errno 2] No such file or directory: 'no_such_file.txt'

KeyError

Ex: 

my_dict = {"key1": "value1", "key2": "value2"}

print(my_dict["no_such_key"])

Result:

KeyError: 'no_such_key'

IndexError

Ex: 

my_list = [1, 2, 3]

print(my_list[4])

Result:

IndexError: list index out of range

TypeError

Ex: 

my_str = "hello"

print(my_str + 123)

Result:

TypeError: can only concatenate str (not "int") to str

How to catch Exceptions

Using the following keywords:

        try:

            Something that might cause an exception.

        except:

            Do this if there was an exception.

        else:

            Do this if there were no exceptions.

        finally:

            Do this no matter what happens.

Ex: 

try:

    file = open("no_such_file.txt")

except:

    print("except")

    file = open("no_such_file.txt", "w")

    file.write("new created file")

else:

    print("else")

    print(file.read())

finally:

    print("finally")

    file.close()

Result (first run):

except

finally

Result (second run):

else

new created file

finally

Our own exceptions?

We can utilize 'raise' statement and some built-in exception to create our own exceptions.

Take the following exp as an example, there is no syntax errors or exceptions if users enter their height larger than 300. But it does not make sense to be an input parameter as human's height.

Ex:

height = float(input("Your height in cm: "))

weight = float(input("Your weight in kg: "))

# Normal Human Being cannot be higher than 300cm

if height > 300:

    raise ValueError("Height should not be larger than 300")

bmi = weight / (height / 100) ** 2

print(f"Your bmi is {weight / (height / 100) ** 2}")

Challenging - Revise NATO Alphabet Project

Catch exceptions if users enter non-alphabet characters.

Ex:

import pandas

# Using pandas to read csv file

nato_phonetic_alphabet_data_frame =

pandas.read_csv("nato_phonetic_alphabet.csv")

# Generate a dictionary to use alphabet as a key and relating word

as a value

# {"A": "Alfa", "B": "Bravo"}

nato_phonetic_alphabet_dict = {

    row["letter"]: row["code"]

    for (index, row) in nato_phonetic_alphabet_data_frame.iterrows()

}

""" Generate phonetic alphabet result based on the user input """

def generate_phonetic_alphabet_result():

    # Ask users to enter a word

    user_input = input("Enter a word? ")

    try:

        # Use List Comprehension to create a result list

        # Loop through all letters of user input and get

the mapping word by dictionary

        result = [nato_phonetic_alphabet_dict[letter] for letter in

user_input.upper()]

    except KeyError:

        # If users enter non-alphabet characters, then we cannot find it

from the nato_phonetic_alphabet_dict dictionary

        # And program will throw KeyError Exception

        print("Sorry, only letters in the alphabet please")

        # In this case, we need to call the self function again

        generate_phonetic_alphabet_result()

    else:

        print(result)

# Call this function to ask user input and then get relating results

generate_phonetic_alphabet_result()

JSON

JSON, JavaScript Object Notation.

Format: (look like python dictionary)

  {

      key: value,

      key: value,

  }

Ex (Write):

import json

# Write

with open("data.json", "w") as file:

    json.dump({"key1": "value1"}, file, indent=4)

Result:

// data.json

  {

      "key1": "value1"

  }

Ex (Read):

import json

# Load

with open("data.json", "r") as file:

    print(json.load(file))

Result:

{'key1': 'value1'}

Ex (Update):

import json

# Update

# Read it frist

with open("data.json", "r") as file:

    # Load JSON file first

    data = json.load(file)

    # Use update to add more data

    data.update(

        {

            "key2": {

                "inner_key1": "innver_value1",

                "inner_key2": "innver_value2",

            }

        }

    )

# Write it back

with open("data.json", "w") as file:

    # Use dump function to write the updated data back to the file

    json.dump(data, file, indent=4)

Result:

// data.json

  {

     "key1": "value1",

          "key2": {

              "inner_key1": "innver_value1",

              "inner_key2": "innver_value2"

      }

  }

Challenging - Revise Password Manager

#1 Save file from txt to json.

#2 Catch Exceptions

#3 Add Search function

Ex:

import random

import tkinter as tk

from tkinter import messagebox

import pyperclip

import json

def find_password():

    """Find password from data.json"""

    website = website_entry.get()

    # Validation

    if len(website) == 0:

        messagebox.showerror(

            title="Info",

message="Please make sure to enter website field"

        )

        return

    try:

        # Load data from data.json

        with open("data.json", encoding="utf-8", mode="r") as file:

            data = json.load(file)

    except FileNotFoundError:

        messagebox.showerror(title="Info", message="No Data File Found")

    else:

        # Continue from try clause

        # If we can find website from data.json

        if website in data:

            websiteObj = data[website]

            messagebox.showinfo(

                title=website,

                message=f"Email:{websiteObj['email']}\nPassword:

{websiteObj['pwd']}",

            )

        else:

            messagebox.showerror(

                title="Info",

message=f"No details for the {website} exists"

            )

def copy_to_clipboard(message):

    """Use pyperclip library to copy message to clipboard"""

    pyperclip.copy(message)

def generate_password():

    """Generate random password and show it to GUI"""

    letters = [

        "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m",

        "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z",

    ]

    numbers = ["0", "1", "2", "3", "4", "5", "6", "7", "8", "9"]

    symbols = ["!", "#", "$", "%", "&", "(", ")", "*", "+"]

    password_letter_list = [

        random.choice(letters) for _ in range(random.randint(8, 10))

    ]

    password_symbols_list = [

        random.choice(symbols) for _ in range(random.randint(2, 4))

    ]

    password_numbers_list = [

        random.choice(numbers) for _ in range(random.randint(2, 4))

    ]

    password_list = password_letter_list + password_symbols_list +

password_numbers_list

    random.shuffle(password_list)

    password = "".join(password_list)

    pwd_entry.insert(0, password)

    copy_to_clipboard(password)

def save():

    """Save user info to the file system"""

    website = website_entry.get()

    username = username_entry.get()

    pwd = pwd_entry.get()

    # Form Validation

    if len(website) == 0 or len(username) == 0 or len(pwd) == 0:

        messagebox.showerror(

            title="Info", message="Please make sure to enter all fields"

        )

        return

    # Pop-up confirmation

    is_ok = messagebox.askokcancel(

        title=website,

        message=f"Is that ok to save {username} / {pwd} ?",

    )

    if is_ok:

        try:

            # Open a file with r mode

            # And load it

            with open("data.json", encoding="utf-8", mode="r") as file:

                data = json.load(file)

        except FileNotFoundError:

            # If there is a file not found exception

            # Then, open a file with w mode

            # And dump to json file directly since it will be the

# first record

            with open("data.json", encoding="utf-8", mode="w") as file:

                json.dump({website: {"email": username, "pwd": pwd}},

file, indent=4)

        else:

            # Continue from try clause

            # Update python object data with the new record

            data.update({website: {"email": username, "pwd": pwd}})

            # Open a file with w mode

            # And write updated python object back to json file

            with open("data.json", encoding="utf-8", mode="w") as file:

                json.dump(data, file, indent=4)

        finally:

            # Clear User Input

            website_entry.delete(0, tk.END)

            pwd_entry.delete(0, tk.END)

# Init

root = tk.Tk()

root.title("Password Manager")

root.config(padx=50, pady=50)

# Init canvas

canvas = tk.Canvas(width=200, height=200)

logo_image = tk.PhotoImage(file="logo.png")

canvas.create_image(100, 100, image=logo_image)

canvas.grid(column=1, row=0)

# Website

website_label = tk.Label(text="Website:")

website_label.grid(column=0, row=1)

website_entry = tk.Entry()

website_entry.grid(sticky="ew", padx=[0, 5], column=1, row=1)

# Focus entry

website_entry.focus()

# Search

search_btn = tk.Button(text="Search", command=find_password)

search_btn.grid(sticky="ew", padx=[5, 0], column=2, row=1)

# Email/Username

username_lable = tk.Label(text="Email/Username:")

username_lable.grid(column=0, row=2)

username_entry = tk.Entry()

username_entry.grid(sticky="ew", column=1, row=2, columnspan=2)

username_entry.insert(0, "frank@demo.com")

# Password

pwd_lable = tk.Label(text="Password:")

pwd_lable.grid(column=0, row=3)

pwd_entry = tk.Entry()

pwd_entry.grid(sticky="ew", padx=[0, 5], column=1, row=3)

# PWD Generation Btn

generate_pwd_btn = tk.Button(text="Generate Password",

command=generate_password)

generate_pwd_btn.grid(sticky="ew", padx=[5, 0], column=2, row=3)

# Add Btn

add_btn = tk.Button(text="Add", command=save)

add_btn.grid(sticky="ew", column=1, row=4, columnspan=2)

# Start the Event Loop

root.mainloop()