# CASE WHEN style operation on DataFrames
**URL:** https://discourse.julialang.org/t/case-when-style-operation-on-dataframes/63414
**Category:** General Usage
**Tags:** dataframes
**Created:** [June 23, 2021, 2:42am UTC](https://discourse.julialang.org/t/case-when-style-operation-on-dataframes/63414 "2021-06-23T02:42:52Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@Ismam](https://discourse.julialang.org/u/Ismam)
#### Post date: [June 23, 2021, 2:42am UTC](https://discourse.julialang.org/t/case-when-style-operation-on-dataframes/63414/1 "2021-06-23T02:42:52Z")
In SQL & R(dplyr) there’s a “case when” style function.
I’m trying to do the equivalent in Julia.
For example suppose I have:
df = DataFrame(A = 1:4, B = [“M”, “F”, “F”, “M”])
4 rows × 2 columns
| | A | B |
| --- | --- | --- |
| | Int64 | String |
| 1 | 1 | M |
| 2 | 2 | F |
| 3 | 3 | F |
| 4 | 4 | M |
In R, I would be able to do:
> library(dplyr)
>
> df = data.frame(A = 1:4,
> B = c(“M”, “F”, “F”, “M”))
>
> df2 = mutate(df, newcol = case\_when(
> A == 2 & B == “F” ~ “bingo”,
> TRUE ~ “no bingo”))
And it would produce a table as such:
I’ve tried Match.jl but it doesn’t seem to broadcast easily to each row.
Both Match.jl and the map function don’t seem to be able to do a test on two columns at the same time (see in the R code how I was able to use an and statement to join a condition on column A and B: A == 2 & B == “F”)
Vectorisation is always nice, buy is it simpler to just use a for loop? I heard Julia doesn’t suffer so much of a performace hit from for loops like languages like Python & R.
Many many thanks!
---
### Author:  [@Skoffer](https://discourse.julialang.org/u/Skoffer)
#### Post date: [June 23, 2021, 3:05am UTC](https://discourse.julialang.org/t/case-when-style-operation-on-dataframes/63414/2 "2021-06-23T03:05:27Z")
> **[Is case\_when needed in DataFrames.jl?](https://bkamins.github.io/julialang/2020/12/18/casewhen.html)**
>
> Introduction
---
### Author:  [@xiaodai](https://discourse.julialang.org/u/xiaodai)
#### Post date: [June 23, 2021, 3:15am UTC](https://discourse.julialang.org/t/case-when-style-operation-on-dataframes/63414/3 "2021-06-23T03:15:57Z")
> [@Ismam](#):
>
> df = DataFrame(A = 1:4, B = [“M”, “F”, “F”, “M”])
`“` this makes it hard to copy and paste code.
---
### Author:  [@Ismam](https://discourse.julialang.org/u/Ismam)
#### Post date: [June 23, 2021, 4:26am UTC](https://discourse.julialang.org/t/case-when-style-operation-on-dataframes/63414/4 "2021-06-23T04:26:33Z")
The composer panel does it automatically.
I put in straight quotes " and it autoformats it.
How do I stop this behaviour? I tried to **escape** it
---
### Author:  [@xiaodai](https://discourse.julialang.org/u/xiaodai)
#### Post date: [June 23, 2021, 4:33am UTC](https://discourse.julialang.org/t/case-when-style-operation-on-dataframes/63414/5 "2021-06-23T04:33:18Z")
> [@Ismam](#):
>
> The composer panel does it automatically.
wow. i thought u put into word and then copied here. haha
also put ``` around code like this
```julia
df = DataFrame(A = 1:4, B = [“M”, “F”, “F”, “M”])
```
makes it stand out and easier to read.
---
### Author:  [@jules](https://discourse.julialang.org/u/jules)
#### Post date: [June 23, 2021, 5:54am UTC](https://discourse.julialang.org/t/case-when-style-operation-on-dataframes/63414/6 "2021-06-23T05:54:25Z")
> [@Ismam](#):
>
> df2 = mutate(df, newcol = case\_when(
> A == 2 & B == “F” ~ “bingo”,
> TRUE ~ “no bingo”))
With DataFrameMacros.jl for example, you could use the ternary expression from Bogumils post relatively clearly:
```julia
using DataFrameMacros
df2 = @transform(df, :newcol = :A == 2 && :B == "F" ? "bingo" : "no bingo")
```
---
### Author:  [@nilshg](https://discourse.julialang.org/u/nilshg)
#### Post date: [June 23, 2021, 8:21am UTC](https://discourse.julialang.org/t/case-when-style-operation-on-dataframes/63414/7 "2021-06-23T08:21:25Z")
Being the base-DataFrames-purist that I am I would do:
```julia
julia> df = DataFrame(A = 1:4, B = ["M", "F", "F", "M"])
4×2 DataFrame
Row │ A B
│ Int64 String
─────┼───────────────
1 │ 1 M
2 │ 2 F
3 │ 3 F
4 │ 4 M
julia> df.newcol = ifelse.((df.A .== 2) .& (df.B .== "F"), "bingo", "no bingo"); df
4×3 DataFrame
Row │ A B newcol
│ Int64 String String
─────┼─────────────────────────
1 │ 1 M no bingo
2 │ 2 F bingo
3 │ 3 F no bingo
4 │ 4 M no bingo
```
---
### Author:  [@xiaodai](https://discourse.julialang.org/u/xiaodai)
#### Post date: [June 23, 2021, 9:28am UTC](https://discourse.julialang.org/t/case-when-style-operation-on-dataframes/63414/8 "2021-06-23T09:28:21Z")
> [@nilshg](#):
>
> `ifelse.((d`
if else doesn’t scale. I like the ternary operator solution in the blog post