Dear group,
Here is the kind of data.frame I obtain every day with my function :
futures <-
structure(list(DESCRIPTION = c("CORN Jul/10", "CORN Jul/10",
"CORN Jul/10", "CORN Jul/10", "CORN Jul/10", "LIVE CATTLE Aug/10",
"LIVE CATTLE Aug/10", "SUGAR NO.11 Jul/10", "SUGAR NO.11 Jul/10",
"SUGAR NO.11 Jul/10", "SUGAR NO.11 Jul/10", "SUGAR NO.11 Jul/10"
), CREATED.DATE = structure(c(18403, 18406, 18406, 18406, 18406,
18407, 18408, 18406, 18407, 18407, 18407, 18407), class = "Date"),
QUANTITY = c(1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1), SETTLEMENT =
c("373.2500",
"373.2500", "373.2500", "373.2500", "373.2500", "90.7750",
"90.7750", "14.9200", "14.9200", "14.9200", "14.9200", "14.9200"
)), .Names = c("DESCRIPTION", "CREATED.DATE", "QUANTITY",
"SETTLEMENT"), row.names = c(NA, 12L), class = "data.frame")
I need then to apply to the df this following code line :
>PosFut=ddply(futures, c("DESCRIPTION","SETTLEMENT"), summarise, POSITION=
sum(QUANTITY))[,c(1,3,2)]
It works perfectly in most of case, BUT I have a new problem: it can
sometime occurs that my df "futures" is empty, with zero rows.
futures <-
structure(list(DESCRIPTION = character(0), CREATED.DATE =
structure(numeric(0), class = "Date"),
QUANTITY = numeric(0), SETTLEMENT = character(0)), .Names =
c("DESCRIPTION",
"CREATED.DATE", "QUANTITY", "SETTLEMENT"), row.names = integer(0), class =
"data.frame")
It is not the usual case, but it can happen. With this df, when I pass the
above mentione line, I get an error :
>PosFut=ddply(futures, c("DESCRIPTION","SETTLEMENT"), summarise, POSITION=
sum(QUANTITY))[,c(1,3,2)]
Error in tapply(1:nrow(data), splitv, list) :
arguments must have same length
How can I avoid this when my df is empty?
Any help is appreciated
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