[Tutor] Function definition with default argument

[Richard Damon]

On 8/22/20 3:17 PM, Alan Gauld via Tutor wrote:
> On 22/08/2020 17:51, Manprit Singh wrote:
>
>> import pandas as pd
>> ser = pd.Series(["M", "F", "M", "F", "F", "M"])
>> function, and if i write a function and call it  as given below ,
>> passing the series  as a default argument in the function :
>>
>> def offcnt(x=ser):
>>     return x.value_counts()
> You almost certainly do not want to do that.
> The reason is that the default argument is the value
> of ser when you define the function. If you change ser
> to something else and then call your function without
> arguments it will still use the old value of ser.

It actually doesn't bind to the original values, but the original
object. If ser is rebound by assignment, you won't see the change, but
if it is mutated to some other state you will.

-- 
Richard Damon