python pandas:将带参数的函数应用于系列.更新 [英] python pandas: apply a function with arguments to a series. Update
问题描述
我想将带参数的函数应用于熊猫系列:我找到了两种不同的 SO 解决方案:
I would like to apply a function with argument to a pandas series: I have found two different solution of SO:
和
它们都依赖于 functool.partial
的使用并且它们工作得非常好.顺便说一下,新版本的 Pandas 支持多个参数:无论如何我不明白它是如何工作的.示例:
both of them rely on the use of functool.partial
and they works absolutely fine. By the way the new version of Pandas support multiple argument: in any case I do not understand how does it works. Example:
a=pd.DataFrame({'x':[1,2],'y':[10,20]})
a['x'].apply(lambda x,y: x+y, args=(100))
它以一个:
TypeError: <lambda>() argument after * must be a sequence, not int
推荐答案
TypeError
表示您将错误的类型传递给 lambda
函数 x +y
.它期望 args
是一个序列,但它得到了一个 int
.你可能认为 (100)
是一个元组(一个序列),但在 python 中,逗号是一个元组:
The TypeError
is saying that you passed the wrong type to the lambda
function x + y
. It's expecting the args
to be a sequence, but it got an int
. You may have thought that (100)
was a tuple (a sequence), but in python it's the comma that makes a tuple:
In [10]: type((100))
Out[10]: int
In [11]: type((100,))
Out[11]: tuple
所以把你的最后一行改为
So change your last line to
In [12]: a['x'].apply(lambda x, y: x + y, args=(100,))
Out[12]:
0 101
1 102
Name: x, dtype: int64
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