IndexError: list index out of range with api

Question

all_currencies = currency_api('latest', 'currencies')  # {'eur': 'Euro', 'usd': 'United States dollar', ...}
all_currencies.pop('brl')
qtd_moedas = len(all_currencies)
texto = f'{qtd_moedas} Moedas encontradas\n\n'
moedas_importantes = ['usd', 'eur', 'gbp', 'chf', 'jpy', 'rub', 'aud', 'cad', 'ars']

while len(moedas_importantes) != 0:
    for codigo, moeda in all_currencies.items():
        if codigo == moedas_importantes[0]:
            cotacao, data = currency_api('latest', f'currencies/{codigo}/brl')['brl'], currency_api('latest', f'currencies/{codigo}/brl')['date']
            texto += f'{moeda} ({codigo.upper()}) = R$ {cotacao}   [{data}]\n'
            moedas_importantes.remove(codigo)
            if len(moedas_importantes) == 0: break  # WITHOUT THIS LINE, GIVES ERROR

为什么会出现此错误？该列表实际上用完了元素，但代码仅适用于 if

Answer 1

你有一个嵌套循环。进入 while 循环，然后立即在 for 循环中开始执行。对于 all_currencies.items() 中的所有元素，执行保留在 for 循环中。每次在 moedas_importantes 的开头找到 codigo 时，都会删除该元素。最终您从 moedas_importantes 中删除了所有元素，但您仍在 for 循环中并检查 if codigo == moedas_importantes[0]。此时 moedas_importantes 是空的所以你得到一个索引错误。

我认为下面的代码可以在没有嵌套循环的情况下运行。请注意，这假设 moedas_importantes 中的所有元素也是 all_currencies.

中的键

all_currencies = currency_api('latest', 'currencies')  # {'eur': 'Euro', 'usd': 'United States dollar', ...}
all_currencies.pop('brl')
qtd_moedas = len(all_currencies)
texto = f'{qtd_moedas} Moedas encontradas\n\n'
moedas_importantes = ['usd', 'eur', 'gbp', 'chf', 'jpy', 'rub', 'aud', 'cad', 'ars']

while len(moedas_importantes) != 0:
    codigo = moedas_importantes[0]
    moeda = all_currencies[codigo]
    cotacao, data = currency_api('latest', f'currencies/{codigo}/brl')['brl'], currency_api('latest', f'currencies/{codigo}/brl')['date']
    texto += f'{moeda} ({codigo.upper()}) = R$ {cotacao}   [{data}]\n'
    moedas_importantes.remove(codigo)

IndexError: list index out of range with api

IndexError: list index out of range with api

python

python-2.7

python-3.x