call a variable name from a dataframe within a function in R

Question

I can't figure out a simple problem of how to call a variable name from a dataframe passed as string( function input).

I have a function defined as:

box_lambda = function(Valuename,data1){
  data1[,Valuename]=ifelse(data1[,Valuename]==0,0.000001,data1[,Valuename])
  b= boxcox(get(Valuename) ~ Age.Group+Sex , data = data1)
  lambda <- b$x[which.max(b$y)]
  return(lambda)
}

But this doesn't work as I get error: Error in eval(f): 'list' object cannot be coerced to type 'double'

I tried data1[[Valuename]]=ifelse(data1[Valuename]]==0,0.000001,data1[[Valuename]])

Any help is appreciated!

asd-tm · Accepted Answer · 2022-10-24T06:36:59.897

First you lost a bracket necessary to address a field:

data1[[Valuename]]

You can also use a seties of other approaches from [here][1] and from [here][2]. For instance you can use:

library(dplyr) 
data %>%
filter(!!as.name(Valuename) == 0)

So finally you can use :

data1[[Valuename]][data1[[Valuename]]==0] <-0.000001

This script will replace 0 with epsilon and leave the other values. [1]: https://stackoverflow.com/a/74173690/5043424 [2]: https://stackoverflow.com/a/48219802/5043424

call a variable name from a dataframe within a function in R

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