Function gsub/sub does not work within function body-CodePudding

I've encountered very strange issue. I definied a function that loads data from online source and returns a dataframe after some transformations. However, I realised that the data in two columns of the output has decimal delimiter ",", which causes R to interpret this columns as factors.

What I've tried to do was to tranform data within function, by adding two additional lines to the function body:

data_table$usd <- as.numeric(sub(",", ".", data_table$usd))
data_table$eur <- as.numeric(sub(",", ".", data_table$eur))

But this turns out to overwrite whole output (data_table) with numerical vector (output of last line of code I guess). On the other hand, when I execute the same exact code outside of a function, it works as I expect, which makes me even more confused.

Any ideas, why the code inside function cannot transform single columns, but overwrites whole dataframe?

CodePudding user response：

I am guessing here, but you probably end the function body with the assignment of the column like so

modified_iris <- function() {
  my_iris <- iris
  my_iris$new <- toupper(iris$Species)
}
head(modified_iris())
#> [1] "SETOSA" "SETOSA" "SETOSA" "SETOSA" "SETOSA" "SETOSA"

Instead, you want to make sure that the full data frame is returned

modified_iris <- function() {
  my_iris <- iris
  my_iris$new <- toupper(iris$Species)
  my_iris
}
head(modified_iris())
#> # A tibble: 6 × 6
#>   Sepal.Length Sepal.Width Petal.Length Petal.Width Species new   
#>          <dbl>       <dbl>        <dbl>       <dbl> <fct>   <chr> 
#> 1          5.1         3.5          1.4         0.2 setosa  SETOSA
#> 2          4.9         3            1.4         0.2 setosa  SETOSA
#> 3          4.7         3.2          1.3         0.2 setosa  SETOSA
#> 4          4.6         3.1          1.5         0.2 setosa  SETOSA
#> 5          5           3.6          1.4         0.2 setosa  SETOSA
#> 6          5.4         3.9          1.7         0.4 setosa  SETOSA