# DataFrames: obtaining the subset of rows by a set of values
**URL:** https://discourse.julialang.org/t/dataframes-obtaining-the-subset-of-rows-by-a-set-of-values/15923
**Category:** New to Julia
**Tags:** dataframes
**Created:** [October 5, 2018, 1:14pm UTC](https://discourse.julialang.org/t/dataframes-obtaining-the-subset-of-rows-by-a-set-of-values/15923 "2018-10-05T13:14:50Z")
**Posts on this page:** 6
**Page:** 3
### Author:  [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)
#### Post date: [October 18, 2018, 3:49pm UTC](https://discourse.julialang.org/t/dataframes-obtaining-the-subset-of-rows-by-a-set-of-values/15923/41 "2018-10-18T15:49:31Z")
> ```
> iris |>
> Filter(Species -> Species == "versicolor") |>
> Map((SepalLength, SepalWidth) -> SepalLength / SepalWidth)
>
> ```
This scares me a bit because it means that fast filtering would have to happen with variables themselves, named in the code, instead of with functions, due to the non-standard evaluation. It’s an R-ism that I want to avoid if possible.
---
### Author:  [@nalimilan](https://discourse.julialang.org/u/nalimilan)
#### Post date: [November 17, 2018, 4:43pm UTC](https://discourse.julialang.org/t/dataframes-obtaining-the-subset-of-rows-by-a-set-of-values/15923/42 "2018-11-17T16:43:26Z")
I’ve opened a WIP PR in DataFrames about using the `select` approach for combining results of a grouping operations: [https://github.com/JuliaData/DataFrames.jl/pull/1601](https://github.com/JuliaData/DataFrames.jl/pull/1601)
---
### Author:  [@josimar](https://discourse.julialang.org/u/josimar)
#### Post date: [December 5, 2022, 3:56pm UTC](https://discourse.julialang.org/t/dataframes-obtaining-the-subset-of-rows-by-a-set-of-values/15923/43 "2022-12-05T15:56:35Z")
Could you please clarify how to type in the Greek symbol on the REPL?
I tried \epsilon but this is not the correct symbol.
I mean the symbol that is written here: filter(row → row.col ∈ [1,2,3], df)
Thanks!
---
### Author:  [@pfitzseb](https://discourse.julialang.org/u/pfitzseb)
#### Post date: [December 5, 2022, 4:16pm UTC](https://discourse.julialang.org/t/dataframes-obtaining-the-subset-of-rows-by-a-set-of-values/15923/44 "2022-12-05T16:16:28Z")
`\in`
---
### Author:  [@nilshg](https://discourse.julialang.org/u/nilshg)
#### Post date: [December 6, 2022, 9:55am UTC](https://discourse.julialang.org/t/dataframes-obtaining-the-subset-of-rows-by-a-set-of-values/15923/45 "2022-12-06T09:55:48Z")
When in doubt ask the REPL:
```julia
help?> ζ
"ζ" can be typed by \zeta
help?> ∈
"∈" can be typed by \in
```
---
### Author:  [@merlin](https://discourse.julialang.org/u/merlin)
#### Post date: [April 27, 2024, 9:32pm UTC](https://discourse.julialang.org/t/dataframes-obtaining-the-subset-of-rows-by-a-set-of-values/15923/46 "2024-04-27T21:32:33Z")
That `∈([1,2,3]).(df.col)` is some niiiiice syntax!
Specifically, nice for getting row number or index to create a `@view` of a dataframe. Views cant be made from the dataframe output of a `filter` or `subset` operation. This had me stumped for a while.
For example, I need to change the cells in column `:X2` if the rows in column `label` match a string:
```jl
df_vw = @view df[∈(["label_p", "label_t", "label_w"]).(df.label), [:X1, :X2]]
# X1 is fraction, make into bips and update cell in :X2
transform!(df_vw, :X1 => ByRow(x -> string(round(Int, x * 100000), " bps")) => :X2)
# alternately with direct assignment:
df_vw[:, :X2 = string.(round.(Int, df_vw[:, :X1] * 10000), " bps")
```
Thanks again, @ExpandingMan !!!
```julia
```
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