R: Summarize Data by Month and Year (Similar to pivot table) -

i trying summarize data in r month , year. using ddply function summarize data want change , doing normal transpose doesn't give me desired results. loading csv file daily river bypass data. data has following fields: date, year, month, day , bypass. use following code summarize file:

summary<- ddply(file,c("year", "month"), summarise, sum =  round(sum(bypass*1.9835),0))  summary 

the output looks like:

year month   sum 1946    10  1791 1946    11  1575 1946    12  1129 1947     1   823 1947     2   750 1947     3  1023 

(and goes on ~61 years of data)

so question... there way transform data output in following way:

                             month year    1   2   3    4   5   6   7   8   9  10      11      12 1946                                        1791    1575    1129 1947    823 750 1023 

i copied in sample of data goes through 2007.

thanks in advance

library(reshape2) dcast(df, iyear ~ month, value.var='sum') 

output:

  iyear   1   2    3   10   11   12 1  1946  na  na   na 1791 1575 1129 2  1947 823 750 1023   na   na   na 

if want replace nas zeros:

df1 <- dcast(df, iyear ~ month, value.var='sum') df1[is.na(df1)] <- 0    iyear   1   2    3   10   11   12 1  1946   0   0    0 1791 1575 1129 2  1947 823 750 1023    0    0    0 

data:

df <- structure(list(iyear = c(1946l, 1946l, 1946l, 1947l, 1947l, 1947l ), month = c(10l, 11l, 12l, 1l, 2l, 3l), sum = c(1791l, 1575l,  1129l, 823l, 750l, 1023l)), .names = c("iyear", "month", "sum" ), class = "data.frame", row.names = c(na, -6l))    iyear month  sum 1  1946    10 1791 2  1946    11 1575 3  1946    12 1129 4  1947     1  823 5  1947     2  750 6  1947     3 1023