How do I search for a value inside a 2d list in python-CodePudding

I am trying to create a program that searches for the exact value of the int in the first index of lists. I have to validate first the input before checking if it exists so I have this function:

fruits = [
    [1001, "Apple", "Red"],
    [1002, "Pear", "Brown"],
    [1003, "Banana", "Yellow"],
    [1004, "Grapes", "Purple"],
]


def validate_int(message):
    while True:
        try:
            intValue = int(input(message))
        except ValueError:
            print("Please enter a valid int. Try again.")
            continue
        else:
            for i in fruits:
                if intValue == i[0]:
                    print("     | ID exists. It is this fruit: ", i[1])
                    validate_int(message)
            else:
                return intValue


print("---------------------------------------")
print("Fruits")
print("---------------------------------------")
fruitID = validate_int("Enter FruitID: ")
fruitName = input("Enter FruitName: ")
fruitColor = input("Enter FruitColor: ")
new_fruit = [fruitID, fruitName, fruitColor]
fruits.append(new_fruit)

for i in fruits:
    print(i)

and when I run this code, it keeps looping and checking if the given input is int and exists, but when I append it to the list, it inputs the first input even if it's wrong, instead of the last correct input. The result looks like this:

---------------------------------------
Fruits
---------------------------------------
Enter FruitID: 1001
     | ID exists. It is this fruit:  Apple
Enter FruitID: 1005
Enter FruitName: Berries
Enter FruitColor: Pink
[1001, 'Apple', 'Red']
[1002, 'Pear', 'Brown']
[1003, 'Banana', 'Yellow']
[1004, 'Grapes', 'Purple']
[1001, 'Berries', 'Pink']

WITH THE CORRECT INPUT:

---------------------------------------
Fruits
---------------------------------------
Enter FruitID: 1234
Enter FruitName: Melon
Enter FruitColor: Orange
[1001, 'Apple', 'Red']
[1002, 'Pear', 'Brown']
[1003, 'Banana', 'Yellow']
[1004, 'Grapes', 'Purple']
[1234, 'Melon', 'Orange']

Instead of 1005 for berries, it returned 1001 even though it went through the validation. If I add the non existing ID the first time, it will append the right ID without any issues. It happens whenever I enter an existing ID for the first time. Any help would be appreciated, thank you

CodePudding user response：

You're recursively calling your function, which effectively starts the while loop again when the int is found --> infinite loop. A better data structure would be to use a dictionary for this problem.

EDIT: I saw you edited your question with desired output. You can let the function return false if it already exists and use an if statement to check function output. I adopted your way of appending new fruits:

def validate_int(message):
    while True:
        try:
            int_value = int(input(message))
        except ValueError:
            print('Please enter valid input')
        
        # loop over fruits 2d list to find fruit
        for fruit in fruits:
            if int_value == fruit[0]:
                # you can join the strings to include color
                print(f"ID exists. This is the fruit: {', '.join(fruit[1:])}")
                return False 
        return int_value
    
fruit_id = validate_int('Enter ID: ')
if fruit_id:
    fruit_name = input('Enter fruit name: ')
    fruit_color = input('Enter color: ') 
    fruits.append([fruit_id, fruit_name, fruit_color])      

for fruit in fruits:
    print(fruit)

CodePudding user response：

fruits = [
    [1001, "Apple", "Red"],
    [1002, "Pear", "Brown"],
    [1003, "Banana", "Yellow"],
    [1004, "Grapes", "Purple"],
]


def validate_int(message):
    new_value = 'NO'
    while True:
        try:
            intValue = int(input(message))
            break # if  there is no error exit the infinite loop
        except ValueError:
            print("Please enter a valid int. Try again.")
            continue
    for i in fruits:
        if intValue == i[0]:
            print("     | ID exists. It is this fruit: ", i[1])
            # remove recursive call
            # validate_int(message)
            return "VALID ID"
    return intValue


print("---------------------------------------")
print("Fruits")
print("---------------------------------------")
fruitID = validate_int("Enter FruitID: ")
if fruitID != "VALID ID":
    fruitName = input("Enter FruitName: ")
    fruitColor = input("Enter FruitColor: ")
    new_fruit = [fruitID, fruitName, fruitColor]
    fruits.append(new_fruit)

for i in fruits:
    print(i)

Test Runs:

---------------------------------------
Fruits
---------------------------------------
Enter FruitID: 1001
     | ID exists. It is this fruit:  Apple
[1001, 'Apple', 'Red']
[1002, 'Pear', 'Brown']
[1003, 'Banana', 'Yellow']
[1004, 'Grapes', 'Purple']

---------------------------------------
Fruits
---------------------------------------
Enter FruitID: 1005
Enter FruitName: Berries
Enter FruitColor: Pink
[1001, 'Apple', 'Red']
[1002, 'Pear', 'Brown']
[1003, 'Banana', 'Yellow']
[1004, 'Grapes', 'Purple']
[1005, 'Berries', 'Pink']