groupBy: Group a datafame by a factor and perform aggreate functions.

In caroline: A Collection of Database, Data Structure, Visualization, and Utility Functions for R

Group a datafame by a factor and perform aggreate functions.

Description

The R equvalent of a SQL 'group by' call.

Usage

groupBy(df, by, aggregation,  clmns=names(df), collapse=',',
                distinct=FALSE, sql=FALSE, full.names=FALSE, ...)

Arguments

df	a data frame.
by	the factor (or name of a factor in df) used to determine the grouping.
aggregation	the functions to perform on the output (default is to sum). Suggested functions are: 'sum','mean','var','sd','max','min','length','paste',NULL.
clmns	the colums to include in the output.
collapse	string delimiter for columns aggregated via 'paste' concatenation.
distinct	used in conjunction with paste and collapse to only return unique elements in a delimited concatenated string
sql	whether or not to use SQLite to perform the grouping (not yet implimented).
full.names	names of the aggregation functions should be appended to the output column names
...	additional parameters (such as na.rm) passed to the underlying aggregate functions.

Value

an summary/aggregate dataframe

See Also

aggregate, bestBy

Examples

df <- data.frame(a=runif(12),b=c(runif(11),NA), 
                 z=rep(letters[13:18],2),w=rep(letters[20:23],3))

groupBy(df=df, by='w', clmns=c(rep(c('a','b'),3),'z','w'), 
 aggregation=c('sum','mean','var','sd','min','max','paste','length'), 
 full.names=TRUE, na.rm=TRUE)
# or using SQLite
groupBy(df=df, by='w', clmns=c(rep(c('a','b'),2),'z','w'), 
        aggregation=c('sum','mean','min','max','paste','length'), 
        full.names=TRUE, sql=TRUE)


## passing a custom function
meantop <- function(x,n=2, ...)
  mean(x[order(x, decreasing=TRUE)][1:n], ...)
  
groupBy(df, by='w', aggregation=rep(c('mean','max','meantop'),2), 
                    clmns=rep(c('a','b'),3), na.rm=TRUE)

caroline documentation built on Oct. 21, 2024, 9:06 a.m.