[R] How to dynamically generate lm() function arguments?

[Gabor Grothendieck]

Using the built in anscombe data frame we can regress y1 on x2 and x4 like this
(place the response first):

lm(anscombe[c("y1", "x2", "x4")])


On Wed, Jul 22, 2009 at 9:50 AM, Moumita
Das<das.moumita.online at gmail.com> wrote:
> Hi All,
> How do you dynamically generate the arguments for the lm() function when
> your items vary for each database.
> Say in my case for a particular database i have items from i1 to i15 .
>
> In the code below there a line like this :--
>  item_cat_fit<-lm(as.numeric(item_item_table$i1) ~
> as.numeric(item_item_table$i2) + as.numeric(item_category_table$i3)  ) *#
> this gives proper results,i am accessing each column of the dataset using
> column names.
> *
> how do i dynamically generate this :---
> item_cat_fit<-lm(as.numeric(item_item_table[item_item_dependent_var_counter])
> ~  as.numeric(item_item_table[item_item_independent_var_counter ] ) )
>
> *Because of this as.numeric(item_item_table[item_item_dependent_var_counter])
> i get error that you cannot convert a list to double.I tried doing this
> as.numeric(as.matrix(item_item_table[item_item_dependent_var_counter]))*
>
> I also tried doing this
> mode(item_item_table[item_item_dependent_var_counter])<-"numeric"  but of no
> use.
>
> for(item_item_dependent_var_counter in 1:item_item_size[1])  # no of all
> items
>  {
>
>
>      for(item_item_independent_var_counter in 1:(item_item_size[1] - 1))
>      {
>
>
> item_item_third_var_data<-contrld_third_var(stringOfItemItemToDataFrameOfItemItem[item_item_dependent_var_counter,1],x<-stringOfItemItemToDataFrameOfItemItem,item__table,regr_type<-"ii")
>
>
>  item_cat_fit<-lm(as.numeric(item_item_table$i1) ~
> as.numeric(item_item_table$i2) )
>  item_cat_fit<-lm(as.numeric(item_item_table[item_item_dependent_var_counter])
> ~  as.numeric(item_item_table[item_item_independent_var_counter ] ) )
>
>                            #print(summary(item_item_fit))
>       }
> }
>
> How can the lm() arguments be generated dynamically.?Would be grateful if
> anyone can come up with a solution for my problem.
> --
> Thanks
> Moumita
>
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>
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