使用pandas_ta计算Stoch RSI时报错ValueError: 传递2个元素预期1个

pandas_ta库的ta.stochrsi()方法默认会同时返回*快K线(STOCHRSIk)和快D线(STOCHRSId)*两个序列，为2列的DataFrame结构。你尝试将2列数据直接赋值给df['stochrsi']这单个列，数据维度不匹配，因此触发了"Wrong number of items passed 2, placement implies 1"的报错。

你可以根据自己的需求选择以下任意一种修改方式：

• 仅需要单个指标时，提取对应列再赋值
  如果你只需要Stoch RSI的K值或者D值，先从返回结果中提取对应单列再赋值即可：

  def stoch_rsi(df, length=14):
      # 先获取stochrsi返回的完整结果
      stochrsi_res = ta.stochrsi(close = df['close'])
      # 仅提取K值赋值，需要D值就替换为STOCHRSId_14_14_3_3
      df['stochrsi'] = stochrsi_res['STOCHRSIk_14_14_3_3']
      return df['stochrsi']
  

• 需要两个指标时，分别赋值给不同的列
  如果你需要同时用到K和D两个值，分别创建两个列存储即可：

  def stoch_rsi(df, length=14):
      stochrsi_res = ta.stochrsi(close = df['close'])
      df['stochrsi_k'] = stochrsi_res['STOCHRSIk_14_14_3_3']
      df['stochrsi_d'] = stochrsi_res['STOCHRSId_14_14_3_3']
      return df[['stochrsi_k', 'stochrsi_d']]
  

• 不确定列名时，先打印结果确认
  如果你修改了stochrsi的默认参数（比如长度、平滑周期），返回的列名后缀会同步变化，可以先执行print(ta.stochrsi(close = df['close']).columns)查看实际列名，再对应提取即可。

import pandas as pd
import pandas_ta as ta
import numpy as np

df = pd.read_csv('data/1d/AAVEUSDT-1d-data.csv')

def stoch_rsi(df, length=14):
    stochrsi_res = ta.stochrsi(close = df['close'])
    df['stochrsi'] = stochrsi_res['STOCHRSIk_14_14_3_3']
    return df['stochrsi']

stoch = stoch_rsi(df)
print(stoch)

内容的提问来源于stack exchange，提问作者Louis