Lambda with two values does not work, error: <lambda>() missing 1 required positional argument: 'y)

Question

我有一个数据框：

data = {'key': ['one', 'two', 'zero'], 'cost': [300, 20, 500], 'leads': [20, 0, 50]} 
    data = pd.DataFrame(data=data)

我想通过如下所示的函数计算新值：

def cpl_calc(x, y):
    if x == 0:
        cpl = y
    else: 
        cpl = y / x
    print(cpl)

当我尝试这样数数时：

data['cpl'] = data[['cost', 'leads']].apply(lambda x, y: cpl_calc(x, y))

我看到以下错误 TypeError: () missing 1 required positional argument: 'y'

如何让公式正确计算新值？

Answer 1

对于您的情况，您可以使用矢量化：

data['cost'].where(data['leads'] == 0, other=data['leads'] / data['cost'])
print(data)

# Output
    key  cost  leads        cpl
0   one   300     20   0.066667
1   two    20      0  20.000000
2  zero   500     50   0.100000

Answer 2

正如@Corralien 所说，最好将其矢量化。看到那个答案。但是要了解如何通过 apply() 函数执行此操作，您可以：

def cpl_calc(x):
    if x['cost'] == 0:
        cpl = x['leads']
    else: 
        cpl = x['leads'] / x['cost']
     
    return cpl

data.apply(cpl_calc, axis=1)

0    0.066667
1    0.000000
2    0.100000

Lambda with two values does not work, error: <lambda>() missing 1 required positional argument: 'y)

Lambda with two values does not work, error: <lambda>() missing 1 required positional argument: 'y)

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