如何在 Python 中查找列表中的最后一个结果？

Question

试图索引最后一个值，但它给我带来了整个列表。

我在 Python 中制定了一个股票市场策略。我用以下方式计算 Williams %R 的指标：

def williamsCalculator(highest, lowest, closing_prices):
    williams_list = [0] * len(highest)
    highest_high = highest.max()
    highest_high = float(highest_high)
    lowest_low = lowest.min()
    lowest_low = float(lowest_low)
    last_close = closing_prices[0]
    #We calculate the Williams %R and we save it in one dataframe.
    williams = ((last_close - highest_high) / (highest_high - lowest_low)) * 100
    williams_list[1:] = williams_list[:-1]
    williams_list[0] = williams
    return williams_list

使用函数和库 CCXT，我从一只股票/加密货币中获取最近 20 分钟的数据，然后我计算了 Williams。

exchange = ccxt.binance({"Public Key": "XXXXX", "Secret Key": "XXXXX"})
prices = exchange.fetch_ohlcv(symbol=market, timeframe="1m", limit=20)

highest_prices = [candle[2] for candle in prices]
highest = pd.DataFrame(highest_prices)

lowest_prices = [candle[3] for candle in prices]
lowest = pd.DataFrame(lowest_prices)

closing_prices = [candle[4] for candle in prices]
closing = pd.DataFrame(closing_prices)

现在我将列表的值赋给一个变量并尝试索引列表的最后一个结果。

williams_list = williamsCalculator(highest, lowest, closing)
last_call = williams_list[0]
print(last_call)

现在这会返回 Williams %R 和他的 dtype 的整个列表。像这样的东西：

[0    -54.488189
1    -45.564304
2    -48.241470
3    -63.044619
4    -46.036745
5    -49.343832
6    -74.068241
7    -67.401575
8    -60.892388
9    -63.202100
10   -82.204724
11   -82.152231
12   -70.026247
13   -85.669291
14   -82.152231
15   -40.997375
16   -24.934383
17   -28.346457
18   -12.650919
19   -28.976378
20   -36.955381
Name: 0, dtype: float64, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

我怎样才能得到 Williams %R 的最后一个值？在这种情况下，我只想要 0 的值，即 -54.488189，没有列名和数据类型。