我有两列要比较每第n行。如果遇到第n行，它将对其进行比较，并将if语句的结果放在新列中。
当我尝试枚举函数时，它总是以if语句的真实部分结尾。不知何故，这段代码总是存在：
如果（count％3）== 0：
for count, factors in enumerate(df.index):
if (count % 3)== 0: #every 3th row
df['Signal']=np.where(df['Wind Ch']>=df['Rain Ch'],'1', '-1')
else:
df['Signal']=0
在“信号”列中，我希望每第3行为“ 1”或“ -1”，而在所有其他行上为“ 0”。但是我在每一行上得到'1'或'-1'
现在我得到：
Date Wind CH Rain CH Signal
0 5/10/2005 -1.85% -3.79% 1
1 5/11/2005 1.51% -1.66% 1
2 5/12/2005 0.37% 0.88% -1
3 5/13/2005 -0.81% 3.83% -1
4 5/14/2005 -0.28% 4.05% -1
5 5/15/2005 3.93% 1.79% 1
6 5/16/2005 6.23% 0.94% 1
7 5/17/2005 -0.08% 4.43% -1
8 5/18/2005 -2.69% 4.02% -1
9 5/19/2005 6.40% 1.33% 1
10 5/20/2005 -3.41% 2.38% -1
11 5/21/2005 3.27% 5.46% -1
12 5/22/2005 -4.40% -4.15% -1
13 5/23/2005 3.27% 4.48% -1
但我想得到：
Date Wind CH Rain CH Signal
0 5/10/2005 -1.85% -3.79% 0.0
1 5/11/2005 1.51% -1.66% 0.0
2 5/12/2005 0.37% 0.88% -1.0
3 5/13/2005 -0.81% 3.83% 0.0
4 5/14/2005 -0.28% 4.05% 0.0
5 5/15/2005 3.93% 1.79% 1.0
6 5/16/2005 6.23% 0.94% 0.0
7 5/17/2005 -0.08% 4.43% 0.0
8 5/18/2005 -2.69% 4.02% -1.0
9 5/19/2005 6.40% 1.33% 0.0
10 5/20/2005 -3.41% 2.38% 0.0
11 5/21/2005 3.27% 5.46% -1.0
12 5/22/2005 -4.40% -4.15% 0.0
13 5/23/2005 3.27% 4.48% 0.0
我在这里想念什么？
最佳答案
您可以这样处理，使用np.vectorize避免循环：
import numpy as np
def calcSignal(x, y, i):
return 0 if (i + 1) % 3 != 0 else 1 if x >= y else -1
func = np.vectorize(calcSignal)
df['Signal'] = func(df['Wind CH'], df['Rain CH'], df.index)
df
Date Wind CH Rain CH Signal
0 5/10/2005 -1.85% -3.79% 0
1 5/11/2005 1.51% -1.66% 0
2 5/12/2005 0.37% 0.88% -1
3 5/13/2005 -0.81% 3.83% 0
4 5/14/2005 -0.28% 4.05% 0
5 5/15/2005 3.93% 1.79% 1
6 5/16/2005 6.23% 0.94% 0
7 5/17/2005 -0.08% 4.43% 0
8 5/18/2005 -2.69% 4.02% -1
9 5/19/2005 6.40% 1.33% 0
10 5/20/2005 -3.41% 2.38% 0
11 5/21/2005 3.27% 5.46% -1
12 5/22/2005 -4.40% -4.15% 0
13 5/23/2005 3.27% 4.48% 0
关于python - 用枚举在第n行中做某事，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/58197650/