StdVisitor error with user-defined type about dataframe

[hosseinmoein]

This may give you some hints: https://stackoverflow.com/questions/33728107/extending-c-math-functions-to-non-fundamental-types

But I think your best option is to use the VarVisitor and then take the sqrt of the variance manually.

[DerryMellon]

I know ADL, but ADL is only valid for usage forms such as sqrt(x), which cannot be found using ::sqrt(x).
StdVisitor is just an example. There are other visitors such as ZScoreVisitor. I don’t want to implement all similar functions by myself.

[hosseinmoein]

Another option I can think of is to implement the cast operator for double for your type

[DerryMellon]

I convert the data to double before putting it into the DataFrame now. thanks anyway