# period.sum

From xts v0.9-7
0th

Percentile

##### Calculate Sum By Period

Calculate a sum for each period of INDEX. Essentially a rolling application of sum over a series of non-overlapping sections.

Keywords
utilities
##### Usage
period.sum(x, INDEX)
##### Arguments
x

a univariate data object

INDEX

a numeric vector of endpoints to calculate sum on

##### Details

Used to calculate a sum per period given an arbitrary index of sections to be calculated over. This is an optimized function for sum. There are additionally optimized versions for min, max, and prod.

For xts-coercible objects, an appropriate INDEX can be derived from a call to endpoints.

##### Value

An xts or zoo object of sums, indexed by the period endpoints.

endpoints, period.max, period.min, period.prod
library(xts) # NOT RUN { period.sum(c(1,1,4,2,2,6,7,8,-1,20),c(0,3,5,8,10)) data(sample_matrix) period.sum(sample_matrix[,1],endpoints(sample_matrix)) period.sum(as.xts(sample_matrix)[,1],endpoints(sample_matrix)) # }