Dear group, Here is my df :
futures <- structure(list(CONTRAT = c("WHEAT May/10 ", "WHEAT May/10 ", "WHEAT May/10 ", "WHEAT May/10 ", "COTTON NO.2 May/10 ", "COTTON NO.2 May/10 ", "COTTON NO.2 May/10 ", "PLATINUM Jul/10 ", " SUGAR NO.11 May/10 ", " SUGAR NO.11 May/10 ", " SUGAR NO.11 May/10 ", " SUGAR NO.11 May/10 ", " SUGAR NO.11 May/10 ", "ROBUSTA COFFEE (10) May/10 ", "ROBUSTA COFFEE (10) May/10 ", "ROBUSTA COFFEE (10) May/10 ", "ROBUSTA COFFEE (10) May/10 ", "ROBUSTA COFFEE (10) May/10 ", "ROBUSTA COFFEE (10) May/10 ", "ROBUSTA COFFEE (10) May/10 ", "ROBUSTA COFFEE (10) May/10 ", "ROBUSTA COFFEE (10) May/10 ", "ROBUSTA COFFEE (10) May/10 ", "ROBUSTA COFFEE (10) May/10 ", "ROBUSTA COFFEE (10) May/10 "), QUANTITY = c(1, 1, 1, 1, 1, 1, 1, -1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1), SETTLEMENT = c("467.7500", "467.7500", "467.7500", "467.7500", "78.1300", "78.1300", "78.1300", "1,739.4000", "16.5400", "16.5400", "16.5400", "16.5400", "16.5400", "1,353.0000", "1,353.0000", "1,353.0000", "1,353.0000", "1,353.0000", "1,353.0000", "1,353.0000", "1,353.0000", "1,353.0000", "1,353.0000", "1,353.0000", "1,353.0000")), .Names = c("CONTRAT", "QUANTITY", "SETTLEMENT"), row.names = c(NA, 25L), class = "data.frame") Here is my code : >opfut=ddply(futures, c("CONTRAT","SETTLEMENT"), summarise, POSITION= sum(QUANTITY)) Here is the output: > opfut CONTRAT SETTLEMENT POSITION 1 SUGAR NO.11 May/10 16.5400 5 2 COTTON NO.2 May/10 78.1300 3 3 PLATINUM Jul/10 1,739.4000 -1 4 ROBUSTA COFFEE (10) May/10 1,353.0000 15 5 WHEAT May/10 467.7500 4 It is almost exactly what I want, except I am expecting the POSITION column before the SETTLEMENT column. How can I modified my code to obtain this? TY *************************** Arnaud Gaboury Mobile: +41 79 392 79 56 BBM: 255B488F ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.