Le lundi 14 novembre 2016 à 14:18 -0800, Hongwei Liu a écrit :

> Hi guys,

>

> I am new to Julia and I have trouble in finding a similar function in

> Julia that has the ability of "update" in R.

>

> For example, set formula = y ~ x1 + x2

>

> In R, I can use update(formula, D ~ . ) to change the formula from y

> ~ x1 + x2 to D ~ x1 + x2

>

> In Julia, the formula's type is DataFrames.Formula and I have

> searched online and Dataframes document for a long time but still

> couldn't find the answer.

>

> So my question is:

>

> Is there are such a function in Julia? If not, is there a way to

> modify a formula directly?

I don't think we provide such a function yet, but you can easily do

that manually.

Use dump() to see what the formula object consists in:

julia> dump(y ~ x1 + x2)

DataFrames.Formula

lhs: Symbol y

rhs: Expr

head: Symbol call

args: Array{Any}((3,))

1: Symbol +

2: Symbol x1

3: Symbol x2

typ: Any

Here, you can just change the rhs (right hand side) argument:

julia> f = y ~ x1 + x2

Formula: y ~ x1 + x2

julia> f.lhs = :D

:D

julia> f

Formula: D ~ x1 + x2

Regards

> Thanks a lot!!

>

> Hongwei