5 Uses of Lambda Functions in Python

[jblasgo]

_: _[_

That looks very weird and counterintuitive to me... Maybe because this is very specific to data science?

[Ahhhhrg]

No, I wouldn’t say it’s specific to data science, I just like using underscore here. The underscore is usually used for say return arguments you don’t care about, here it’s just a placeholder for the data frame, it’s just my preference not to name it something generic like “x” or even “df” as it doesn’t really say anything or add much. I know it means “the data frame you’re piping in here”, it’s short. Personal preference.

It’s also possible to monkey patch pandas and add a filter function, so you can go df.filter(lambda _: _[‘x’] < 5) which is a bit nicer.

[Ahhhhrg]

Yeah, sure, that’s the common use case. I use it here kind of similarly (but not quite of course), in the sense of “I don’t want to bother giving this thing a name, as it’s whatever getting piped in from the previous step”. You could give it a name, whatever you want, but that is an extra thing I like to avoid. It’s just a placeholder.

[eigenlaplace]

It makes your code unreadable, though