I would like to insert a blank column in between "Delta = delta" and "Card = vars" in the dataframe below. I would also like to sort the output by the column "Model_Avg_Error" in the dataframe as well.

df = data.frame(Card = vars, Model_Avg_Error = model_error, Forecast = forecasts,  Delta = delta, ,Card = vars, Model_Avg_Error = model_error, 
                Forecast = forecasts,  Delta = delta)

# save
write.csv(df, file = file.path(proj_path, "output.csv"), row.names = F)

This was the error received from above:

Error in data.frame(Card = vars, Model_Avg_Error = model_error, Forecast = forecasts, : argument is missing, with no default