Question

I need to create a dataframe and passing the name of the columns with variables.

Now, I can do: df$name1 df$name2

BUT

How to do the same thing having 'name1' and 'name2‘ in a variable? How can I do some thing like:

df$THE_VARIABLE (that have the name of the column)

Answer 1

To do this, use the [[ operator:

df[[the_variable]]

Here is an example using iris:

> someCol <- "Species"
> head(iris[[someCol]])
[1] setosa setosa setosa setosa setosa setosa
Levels: setosa versicolor virginica