arguments_checks: Perform necessary preliminary checks on arguments that are passed to joyn

Description

Perform necessary preliminary checks on arguments that are passed to joyn

Usage

arguments_checks(
  x,
  y,
  by,
  copy,
  keep,
  suffix,
  na_matches,
  multiple,
  relationship,
  reportvar
)

Value

list of checked arguments to pass on to the main joyn function

Arguments

x

data frame: left table

y

data frame: right table

by

character vector or variables to join by

copy

If x and y are not from the same data source, and copy is TRUE, then y will be copied into the same src as x. This allows you to join tables across srcs, but it is a potentially expensive operation so you must opt into it.

keep

Should the join keys from both x and y be preserved in the output?

If NULL, the default, joins on equality retain only the keys from x, while joins on inequality retain the keys from both inputs.
If TRUE, all keys from both inputs are retained.
If FALSE, only keys from x are retained. For right and full joins, the data in key columns corresponding to rows that only exist in y are merged into the key columns from x. Can't be used when joining on inequality conditions.

suffix

If there are non-joined duplicate variables in x and y, these suffixes will be added to the output to disambiguate them. Should be a character vector of length 2.

na_matches

Should two NA or two NaN values match?

"na", the default, treats two NA or two NaN values as equal, like %in%, match(), and merge().
"never" treats two NA or two NaN values as different, and will never match them together or to any other values. This is similar to joins for database sources and to base::merge(incomparables = NA).

multiple

Handling of rows in x with multiple matches in y. For each row of x:

"all", the default, returns every match detected in y. This is the same behavior as SQL.
"any" returns one match detected in y, with no guarantees on which match will be returned. It is often faster than "first" and "last" if you just need to detect if there is at least one match.
"first" returns the first match detected in y.
"last" returns the last match detected in y.

relationship

Handling of the expected relationship between the keys of x and y. If the expectations chosen from the list below are invalidated, an error is thrown.

NULL, the default, doesn't expect there to be any relationship between x and y. However, for equality joins it will check for a many-to-many relationship (which is typically unexpected) and will warn if one occurs, encouraging you to either take a closer look at your inputs or make this relationship explicit by specifying "many-to-many".

See the Many-to-many relationships section for more details.
"one-to-one" expects:
- Each row in x matches at most 1 row in y.
- Each row in y matches at most 1 row in x.
"one-to-many" expects:
- Each row in y matches at most 1 row in x.
"many-to-one" expects:
- Each row in x matches at most 1 row in y.
"many-to-many" doesn't perform any relationship checks, but is provided to allow you to be explicit about this relationship if you know it exists.

relationship doesn't handle cases where there are zero matches. For that, see unmatched.

reportvar

character: Name of reporting variable. Default is ".joyn". This is the same as variable "_merge" in Stata after performing a merge. If FALSE or NULL, the reporting variable will be excluded from the final table, though a summary of the join will be display after concluding.