opendataformat (version 2.2.2)

merge.odf_tbl: Merge method for odf tibbles.

Description

Merge two odf tibbles in R while keeping attributes with metadata.

Usage

# S3 method for odf_tbl
merge(
  x,
  y,
  by = NULL,
  by.x = NULL,
  by.y = NULL,
  all = FALSE,
  all.x = all,
  all.y = all,
  sort = TRUE,
  suffixes = c(".x", ".y"),
  no.dups = TRUE,
  allow.cartesian = getOption("datatable.allow.cartesian"),
  incomparables = NULL,
  ...
)

Value

A new odf tibble build from the two input data.frames with the variable attributes from the original data.frames. Sorted by the columns set (or inferred for) the by argument if argument sort is set to TRUE. For variables/columns occurring in both x and y, attributes are taken from x.

Arguments

x, y

odf tibbles, or objects to be coerced to one

by

A vector of shared column names in x and y to merge on. This defaults to the shared key columns between the two tables. If y has no key columns, this defaults to the key of x.

by.x, by.y

Vectors of column names in x and y to merge on.

all

logical; all = TRUE is shorthand to save setting both all.x = TRUE and all.y = TRUE.

all.x

logical; if TRUE, rows from x which have no matching row in y are included. These rows will have 'NA's in the columns that are usually filled with values from y. The default is FALSE so that only rows with data from both x and y are included in the output.

all.y

logical; analogous to all.x above.

sort

logical. If TRUE (default), the rows of the merged data.table are sorted by setting the key to the by / by.x columns. If FALSE, unlike base R's merge for which row order is unspecified, the row order in x is retained (including retaining the position of missings when all.x=TRUE), followed by y rows that don't match x (when all.y=TRUE) retaining the order those appear in y.

suffixes

A character(2) specifying the suffixes to be used for making non-by column names unique. The suffix behaviour works in a similar fashion as the merge.data.frame method does.

no.dups

logical indicating that suffixes are also appended to non-by.y column names in y when they have the same column name as any by.x.

allow.cartesian

See allow.cartesian in data.table.

incomparables

values which cannot be matched and therefore are excluded from by columns.

...

Not used at this time.

Details

merge is a generic function in base R. It dispatches to either the merge.data.frame method, merge.odf_tbl or merge.data.table method depending on the class of its first argument. merge.odf_tbl uses the merge.data.table to join data.frame and adds the attributes containing metadata from the two original odf data.frames. Note that, unlike SQL join, NA is matched against NA (and NaN against NaN) while merging. For a more data.table-centric way of merging two data.tables, see data.table. See FAQ 1.11 for a detailed comparison of merge.

Examples

# get path to example data from the opendataformat package (data.zip)
path  <-  system.file("extdata", "data.odf.zip", package = "opendataformat")

# read four columns of example data specified as ODF from ZIP file
df  <-  read_odf(file = path, select = 1:4)

# read other columns of example data specified as ODF from ZIP file
df2  <-  read_odf(file = path, select = 4:7)

# generate a variable for joining both datasets:
df$id<-1:20
df2$id<-1:20

# merge both datasets by id column
merged_df<-merge(df, df2)

#merge both datasets by shared key columns between the two tables
merged_df2<-merge(df, df2)