r - getting from histogram counts to cdf -

i have dataframe have values, , each value have counts associated value. so, plotting counts against values gives me histogram. have 3 types, a, b, , c.

              value  counts     type                    0 139648267                     1  34945930                     2   5396163                     3   1400683                     4    485924                     5    204631                     6     98599                     7     53056                     8     30929                     9     19556                    10     12873                    11      8780                    12      6200                    13      4525                    14      3267                    15      2489                    16      1943                    17      1588                   ...     ...   ... 

how cdf?

so far, approach super inefficient: first write function sums counts value:

get_cumulative <- function(x) {   result <- numeric(nrow(x))    (i in seq_along(result)) {    result[i] = sum(x[x$num_groups <= x$num_groups[i], ]$count)   }   x$cumulative <- result   x } 

then wrap in ddply splits type. not best way, , i'd love suggestions on how proceed.

you can use ave , cumsum (assuming data in df , sorted value):

transform(df, cdf=ave(counts, type, fun=function(x) cumsum(x) / sum(x))) 

here toy example:

df <- data.frame(counts=sample(1:100, 10), type=rep(letters[1:2], each=5)) transform(df, cdf=ave(counts, type, fun=function(x) cumsum(x) / sum(x))) 

that produces:

   counts type       cdf 1      55    0.2750000 2      61    0.5800000 3      27    0.7150000 4      20    0.8150000 5      37    1.0000000 6      45    b 0.1836735 7      79    b 0.5061224 8      12    b 0.5551020 9      63    b 0.8122449 10     46    b 1.0000000