CODEWITHSUNDEEP
r
RoiMinuit
RoiMinuit

Reputation: 414

Add a Column created Within a Function to a dataframe in R

I have searched and tried multiple previously asked questions that might be similar to my question, but none worked.

I have a dataframe in R called df2, a column called df2$col. I created a function to take the df, the df$col, and two parameters that are names for two new columns I want created and worked on within the function. After the function finishes running, I want a return df with the two new columns included. I get the two columns back indeed, but they are named after the placeholders in the function shell. See below:

df2 = data.frame(col = c(1, 3, 4, 5), 
                col1 = c(9, 6, 8, 3),
                col2 = c(8, 2, 8, 4))

the function I created will take col and do something to it; return the transformed col, as well as the two newly created columns:

no_way <- function(df, df_col_name, df_col_flagH, df_col_flagL) {

  lo_perc <- 2
  hi_perc <- 6

  df$df_col_flagH <- as.factor(ifelse(df_col_name<lo_perc, 1, 0))
  df$df_col_flagL <- as.factor(ifelse(df_col_name>hi_perc, 1, 0))

  df_col_name <- df_col_name + 1.4
  df_col_name <- df_col_name * .12
  
  return(df)

}

When I call the function, no_way(df2, col, df$new_col, df$new_col2), instead of getting a df with col, col1, col2, new_col1, new_col2, I get the first three right but get the parametric names for the last two. So something like df, col, col1, col2, df_col_flagH, df_col_flagL. I essentially want the function to return the df with the new columns' names I give it when I am calling it. Please help.

Upvotes: 0

Views: 134

Answers (2)

RoiMinuit
RoiMinuit

Reputation: 414

I needed to call the function with the new column names as strings instead:

no_way(mball, 'TEAM_BATTING_H', 'hi_TBH', 'lo_TBH')

Additionally, I had to use brackets around the target column in my function.

Upvotes: 0

Tech Commodities
Tech Commodities

Reputation: 1959

I don't see what your function is trying to do, but this might point you in the right direction:

no_way <- function(df = df2, df_col_name = "col", df_col_flagH = "col1", df_col_flagL = "col2") {
  
  lo_perc <- 2
  hi_perc <- 6
  
  df[[df_col_flagH]] <- as.factor(ifelse(df[[df_col_name]] < lo_perc, 1, 0)) # as.factor? 
  df[[df_col_flagL]] <- as.factor(ifelse(df[[df_col_name]] > hi_perc, 1, 0))
        
  df[[df_col_name]] <- (df[[df_col_name]] + 1.4) * 0.12 # Do in one step      
  
  return(df)     
}

Upvotes: 1

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