Sort by Month and Year in Dataframe [duplicate]

Answer 1

As @lmo has already mentioned that using just %m/%Y will not create a valid date. One solution is to use as.yearmon from zoo package.

library(zoo)    
df_prod<-df_prod[order(as.yearmon(df_prod$date,format="%m/%Y")),]

Answer 2

%m/%Y is a tricky starting format for a date, if that's what you ultimately need:

grab date components from the string:

aa <- format(Sys.Date(), "%m/%Y")
m <- as.numeric(substr(aa, 1, 2))
y <- as.numeric(substr(aa, 4, 8))

Then you can paste them together into a date format and sort:

as.Date(paste(y, "-", m, "-01", sep = ''))