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mrgBased directly on the standard R merge function for a horizontal merge that combines data frames horizontally, that is, adds variables (columns) to an existing data frame according to a common shared ID field. 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. Any existing variable labels in the input data frames are retained in the merged data frame.
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.
Merge(data1, data2, by=NULL, quiet=getOption("quiet"), ...)
mrg(...)"row.names" for merging
according to the row names.TRUE, no text output. Can change system default
with theme function.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.mydata as in the examples below. This is the default name for the data frame input into the lessR data analysis functions.
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.
merge, rbind.
# 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)
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