Ref_Date    GEO                    PRI                                SEAS                                         EST    Vector Coordinate      Value
1  1981/03 Canada Chained (2007) dollars Seasonally adjusted at annual rates Final consumption expenditure (x 1,000,000) v62305723    1.1.1.1 604670.000
2  1981/06 Canada Chained (2007) dollars Seasonally adjusted at annual rates Final consumption expenditure (x 1,000,000) v62305723    1.1.1.1 603745.000
3  1981/09 Canada Chained (2007) dollars Seasonally adjusted at annual rates Final consumption expenditure (x 1,000,000) v62305723    1.1.1.1 603415.000
4  1981/12 Canada Chained (2007) dollars Seasonally adjusted at annual rates Final consumption expenditure (x 1,000,000) v62305723    1.1.1.1 604700.000
5  1982/03 Canada Chained (2007) dollars Seasonally adjusted at annual rates Final consumption expenditure (x 1,000,000) v62305723    1.1.1.1 596566.000
6  1982/06 Canada Chained (2007) dollars Seasonally adjusted at annual rates Final consumption expenditure (x 1,000,000) v62305723    1.1.1.1 594937.000

for (est in unique(EST)) {
  if (!grepl("(x 1,000,000)", est)) {
    string_list = strsplit(est, " ");
    name = "";
    for (string in string_list) {
      name = paste(substr(string,1,1), name, " ");
    }
    assign(toupper(name), GDP[which(EST==est &
                             PRI=="Current prices" &
                             SEAS=="Seasonally adjusted at annual rates"),
                     c(1,8)]);
  }
}

Warning messages:
1: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
2: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
3: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
4: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
5: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
6: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
7: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
8: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
9: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
10: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
11: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
12: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
13: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
14: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
15: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
16: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
17: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
18: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
19: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
20: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
21: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
22: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
23: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
24: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
25: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
26: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name
27: In assign(toupper(name), GDP[which(EST == est & PRI ==  ... :
  only the first element is used as variable name