Question

我创建了一个价格数据框架，移动平均线，现在是“maX”列，突出显示2个移动平均线何时交叉;

             OPEN   HIGH    LOW   LAST     ma5     ma8  ma21  maX
Date                                                             
11/23/2009  88.84  89.19  88.58  88.97     NaN     NaN   NaN  0.0
11/24/2009  88.97  89.07  88.36  88.50     NaN     NaN   NaN  0.0
11/25/2009  88.50  88.63  87.22  87.35     NaN     NaN   NaN  0.0
11/26/2009  87.35  87.48  86.30  86.59     NaN     NaN   NaN  0.0
11/27/2009  86.59  87.02  84.83  86.53  87.588     NaN   NaN  0.0
11/30/2009  87.17  87.17  85.87  86.41  87.076     NaN   NaN  0.0
12/1/2009   86.41  87.53  86.17  86.68  86.712     NaN   NaN  0.0
12/2/2009   86.68  87.49  86.59  87.39  86.720  87.302   NaN  0.0
12/3/2009   87.39  88.48  87.32  88.26  87.054  87.214   NaN  0.0
12/4/2009   88.26  90.77  88.00  90.56  87.860  87.471   NaN  0.0

但是为什么我无法迭代他的新专栏？我的代码;

Buy = [0,]
maXLast = [0]
for i in maX[1:]: 
    if i == 1 and maXLast == 0:
        Buy.append(1)
    elif i == 1 and maX == -1:
        Buy.append(0)
    else:
        Buy.append(0)
    maXLast = i

print(Buy)       
Entry = pd.DataFrame(Buy,index = dfmas.index).astype('float') 
Entry.columns = ['Buy']
print(Entry)

但是为什么我的代码只返回[0,0]代表'买'而不是1850浮动列表。

那么为什么'回'会回来;

ValueError: Shape of passed values is (1, 2), indices imply (1, 1850)    ???

非常感谢提前！

Answer 1

不要在Pandas中使用for循环。相反，它是矢量化的方式，它将快一千倍：

import numpy as np
Buy = np.where(maX == 1, 1, 0)

无论如何都要这样 - 你可能需要在np.where()中调整条件。

为什么我不能遍历数据框中的新列？

1 个答案: