# DataFrame isin operation
**URL:** https://discourse.julialang.org/t/dataframe-isin-operation/72825
**Category:** New to Julia
**Tags:** dataframes
**Created:** [December 9, 2021, 1:29pm UTC](https://discourse.julialang.org/t/dataframe-isin-operation/72825 "2021-12-09T13:29:11Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@gjh](https://discourse.julialang.org/u/gjh)
#### Post date: [December 9, 2021, 1:29pm UTC](https://discourse.julialang.org/t/dataframe-isin-operation/72825/1 "2021-12-09T13:29:11Z")
Is there a function that would allow selecting rows/columns with isin?
df = DataFrame(Column1 = [“a”, "b, “c”, “d”, “e”, “f”],
Column2 = [1, 2, 3, 1, 2, 3],
)
keep = [“a”, “c”, “e”]
df[isin(df.Column1, keep), :]
---
### Author:  [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)
#### Post date: [December 9, 2021, 1:33pm UTC](https://discourse.julialang.org/t/dataframe-isin-operation/72825/2 "2021-12-09T13:33:13Z")
There is a function to do this. You would just need to do
```julia
in.(df.Column1, Ref(keep))
```
_but_ with questions like these, usually what people really need is an `innerjoin`.
---
### Author:  [@bkamins](https://discourse.julialang.org/u/bkamins)
#### Post date: [December 9, 2021, 1:52pm UTC](https://discourse.julialang.org/t/dataframe-isin-operation/72825/3 "2021-12-09T13:52:46Z")
or `in.(df.Column1, Ref(Set(keep)))` if `keep` and `:Column1` are long and performance matters.
However, as @pdeffebach commented `innerjoin` is optimized to do such operations efficiently (e.g. if your data would be sorted it would take advantage of this fact and such thing is ignored by `in`).
---
### Author:  [@gjh](https://discourse.julialang.org/u/gjh)
#### Post date: [December 9, 2021, 3:23pm UTC](https://discourse.julialang.org/t/dataframe-isin-operation/72825/4 "2021-12-09T15:23:47Z")
thank you both!
---
### Author:  [@nilshg](https://discourse.julialang.org/u/nilshg)
#### Post date: [December 9, 2021, 3:55pm UTC](https://discourse.julialang.org/t/dataframe-isin-operation/72825/5 "2021-12-09T15:55:31Z")
I won’t let one of these threads go by without mentioning my favourite use of the Fix2 syntax:
```julia
in(keep).(df.Column1)
```
(or `Set(keep)` as Bogumil said)