Computes the prior to or reverse cumulative sum of a vector.

Source: R/FSAUtils.R

Computes the prior-to (i.e., the cumulative sum prior to but not including the current value) or the reverse (i.e., the number that large or larger) cumulative sum of a vector. Also works for 1-dimensional tables, matrices, and data.frames, though it is best used with vectors.

rcumsum(x)

pcumsum(x)

Arguments

x

a numeric object.

Value

A numeric vector that contains the prior-to or reverse cumulative sums.

Note

An NA in the vector causes all returned values at and after the first NA for pcumsum and at and before the last NA for rcumsum to be NA. See the examples.

See also

cumsum.

Author

Derek H. Ogle, derek@derekogle.com

Examples

## Simple example
cbind(vals=1:10,
      cum=cumsum(1:10),
      pcum=pcumsum(1:10),
      rcum=rcumsum(1:10))

#>       vals cum pcum rcum
#>  [1,]    1   1    0   55
#>  [2,]    2   3    1   54
#>  [3,]    3   6    3   52
#>  [4,]    4  10    6   49
#>  [5,]    5  15   10   45
#>  [6,]    6  21   15   40
#>  [7,]    7  28   21   34
#>  [8,]    8  36   28   27
#>  [9,]    9  45   36   19
#> [10,]   10  55   45   10

## Example with NA
vals <- c(1,2,NA,3)
cbind(vals,
      cum=cumsum(vals),
      pcum=pcumsum(vals),
      rcum=rcumsum(vals))

#>      vals cum pcum rcum
#> [1,]    1   1    0   NA
#> [2,]    2   3    1   NA
#> [3,]   NA  NA   NA   NA
#> [4,]    3  NA   NA    3

## Example with NA
vals <- c(1,2,NA,3,NA,4)
cbind(vals,
      cum=cumsum(vals),
      pcum=pcumsum(vals),
      rcum=rcumsum(vals))

#>      vals cum pcum rcum
#> [1,]    1   1    0   NA
#> [2,]    2   3    1   NA
#> [3,]   NA  NA   NA   NA
#> [4,]    3  NA   NA   NA
#> [5,]   NA  NA   NA   NA
#> [6,]    4  NA   NA    4
      
## Example with a matrix
mat <- matrix(c(1,2,3,4,5),nrow=1)
cumsum(mat)

#> [1]  1  3  6 10 15
pcumsum(mat)

#>      [,1] [,2] [,3] [,4] [,5]
#> [1,]    0    1    3    6   10
rcumsum(mat)

#> [1] 15 14 12  9  5

## Example with a table (must be 1-d)
df <- sample(1:10,100,replace=TRUE)
tbl <- table(df)
cumsum(tbl)

#>   1   2   3   4   5   6   7   8   9  10 
#>  12  23  34  43  51  59  65  78  87 100 
pcumsum(tbl)

#> df
#>  1  2  3  4  5  6  7  8  9 10 
#>  0 12 23 34 43 51 59 65 78 87 
rcumsum(tbl)

#>   1   2   3   4   5   6   7   8   9  10 
#> 100  88  77  66  57  49  41  35  22  13 

## Example with a data.frame (must be 1-d)
df <- sample(1:10,100,replace=TRUE)
tbl <- as.data.frame(table(df))[,-1]
cumsum(tbl)

#>  [1]   4  17  26  38  47  54  73  82  93 100
pcumsum(tbl)

#>  [1]  0  4 17 26 38 47 54 73 82 93
rcumsum(tbl)

#>  [1] 100  96  83  74  62  53  46  27  18   7