Deprecated regroup instruction in R, change to group_by - r

Question

Suppose this table:
Browse[2]> tra_all_data
ID CITY COUNTRY PRODUCT CATEGORY YEAR INDICATOR COUNT
1 1 VAL ES Tomato Vegetables 1999 10 10
2 2 MAD ES Beer Alcohol 1999 20 20
3 3 LON UK Whisky Alcohol 1999 30 30
4 4 VAL ES Tomato Vegetables 2000 100 100
5 5 VAL ES Beer Alcohol 2000 121 121
6 6 LON UK Whisky Alcohol 2000 334 334
7 7 MAD ES Tomato Vegetables 2000 134 134
8 8 LON UK Tomato Vegetables 2000 451 451
17 17 BIL ES Pincho Meat 1999 180 180
18 18 VAL ES Orange Vegetables 1999 110 110
19 19 MAD ES Wine Alcohol 1999 120 120
20 20 LON UK Wine Alcohol 1999 230 230
21 21 VAL ES Orange Vegetables 2000 100 100
22 22 VAL ES Wine Alcohol 2000 122 122
23 23 LON UK JB Alcohol 2000 133 133
24 24 MAD ES Orange Vegetables 2000 113 113
25 25 MAD ES Orange Vegetables 2000 113 113
26 26 LON UK Orange Vegetables 2000 145 145
And this piece of code:
CURRENT_COLS<-c("PRODUCT", "YEAR", "CITY")
tra_dAGG <- tra_all_data
regroup(as.list(CURRENT_COLS)) %>%
#group_by(PRODUCT, YEAR, CITY) %>%
summarise(Percent = sum(COUNT)) %>%
mutate(Percent = Percent / sum(Percent))
If I use this code as it is, I get the following warning:
Warning message:
'regroup' is deprecated.
Use 'group_by_' instead.
See help("Deprecated")
If I comment the regroup line and use the group_by line, it works but the point is that CURRENT_COLS changes in each iteration and I need to use this variable (I have explicitly defined CURRENT_COLS in this code to better explain my question)
Can anyone help me on this issue? How can I use a variable in the group_by?
Thank you so much in advance.
My R version: 3.1.2 (2014-10-31)

Answer 1

You need to use the newer standard evaluation versions of dplyr's functions. They are denoted by an additional _ at the end of the function name, for example select_().
In your case, you can change your code to:
CURRENT_COLS<-c("PRODUCT", "YEAR", "CITY")
tra_dAGG <- tra_all_data
group_by_(.dots = CURRENT_COLS) %>%
summarise(Percent = sum(COUNT)) %>%
mutate(Percent = Percent / sum(Percent))
Make sure you have the latest versions of dplyr installed and loaded.
To learn more about standard/non-standard evaluation in dplyr, see the vignette NSE.