从字典中删除项目，并在 0 处停止

Question

My current code removes the items in the dictionary and decreases the item count by 1. But it also decreases the count after 0 (eg -1, -2)

import random
item = {"HSE" : 8, "FAC" : 8, "SHP" : 8, "HWY" : 8, "BCH" : 8}
item_list = list(item)

def find_random1():                
    random_building1 = random.choice(item_list)
    item[random_building1] -= 1
    return random_building1

find_random1()   #do this a couple of times if needed

print("Building    Remaining")
print("--------    ---------")
for i in item:
    print("{:<13s}{:<d}".format(i, item[i]))

You can do find_random1() a couple of times or add a second find_random() function to speed up the subtraction of items. This is meant to be a random item picker. After an item is selected at random, the item count in the dictionary would decrease by 1. If the item's count is 0, it would not be picked. What I expect to get is the table below for the print function

Building    Remaining
--------    ---------
HSE          0
FAC          0
...         ...
BCH          0

How do I check if the item in the dictionary is more than 0 before selecting it at random and decreasing the value? Any suggestions? (Sorry if I sounded rude in this post)

Answer 1

Just add an if condition to decrement the value only if the value is greater than 0.

I have tried to run the find_random1() for 10 times to show you the output.

import random
item = {"HSE" : 8, "FAC" : 8, "SHP" : 8, "HWY" : 8, "BCH" : 8}
item_list = list(item)

def find_random1():                
    for i in item_list:
        random_building1 = random.choice(item_list)
        if item[random_building1] > 0:
            item[random_building1] -= 1
    return random_building1

for _ in range(10):
    find_random1()   #do this a couple of times if needed

print("Building    Remaining")
print("--------    ---------")
for i in item:
    print("{:<13s}{:<d}".format(i, item[i]))

Output:

Building    Remaining
--------    ---------
HSE          0
FAC          0
SHP          0
HWY          0
BCH          2

Answer 2

Your code will not execute.

random.choice() isn't doing what you would hope. In the first iteration of your for loop, random_building1 will contain a single character (either one of 'H', 'S' or 'E'). When you try to index the item list using that single character you will get a KeyError exception