lessR (version 3.6.2)

Merge: Merge Two Data Frames Horizontally or Vertically

Description

Abbreviation: mrg

A horizontal merge combines data frames horizontally, that is, adds variables (columns) to an existing data frame according to a common shared ID field. Performs the horizontal merge based directly on the standard R merge function. The vertical merge is based on the rbind function in which the two data frames have the same variables but different cases (observations), so the rows build vertically, stacked on top of each other.

The advantages of this lessR function is that it provides a single function for merging data frames, adds text output to the standard R functions that provide feedback regarding properties of the merge, provides more detailed and presumably more useful error messages, and preserves any variable labels that might exist in one or both of the merged data frames.

Usage

Merge(data1, data2, by=NULL, quiet=getOption("quiet"), …)
mrg(…)

Arguments

data1

The name of the first data frame from which to create the merged data frame.

data2

The name of the second data frame from which to create the merged data frame.

by

If specified, then signals a horizontal merge and the ID field by which the data frames are merged. Specify "row.names" for merging according to the row names.

quiet

If set to TRUE, no text output. Can change system default with style function.

…

Additional arguments available in the base R merge function such as all.x=TRUE for retaining all rows of the first data frame even if not matched by a row in the second data table.

Value

The merged data frame is returned, usually assigned the name of mydata as in the examples below. This is the default name for the data frame input into the lessR data analysis functions.

Details

Merge creates a merged data frame from two input data frames.

If by is specified the merge is horizontal. That is the variables in the second input data frame are presumed different from the variables in the first input data frame. The merged data frame is the combination of variables from both input data frames, with the rows aligned by the value of by, an ID field common to both data frames.

If by is not provided, then the merge is vertical. The variables are presumed the same in each input data frame. The merged data frame consists of the rows of both input data frames. The rows of the first data frame are stacked upon the rows of the second data frame.

Guidance and feedback regarding the merge are provided by default. The first five lines of each of the input data frames are listed before the merge operation, followed by the first five lines of the output data frame.

See Also

merge, rbind.

Examples

# NOT RUN {
# Horizontal
#-----------
mydata <- Read("Employee", format="lessR", quiet=TRUE)
Emp1a <- Subset(1:4, columns = c("Years", "Gender", "Dept", "Salary"))
Emp1b <- Subset(1:4, columns = c("Satisfaction", "HealthPlan"))
# horizontal merge
mydata <- Merge(Emp1a, Emp1b, by="row.names")
# suppress output to console
mydata <- Merge(Emp1a, Emp1b, by="row.names", quiet=TRUE)

# Vertical
#---------
mydata <- Read("Employee", format="lessR", quiet=TRUE)
Emp2a <- Subset(1:4)
Emp2b <- Subset(7:10)
# vertical merge
mydata <- Merge(Emp2a, Emp2b)


# }