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R6 Class to store relationships for joining datasets

JoinKeys.Rd

[Stable] This class stores symmetric links between pairs of key-values (e.g. column A of dataset X can be joined with column B of dataset Y). This relationship is more general than the SQL foreign key relationship which also imposes constraints on the values of these columns.

Methods

Public methods

Method new()

Create a new object of JoinKeys

Usage 

JoinKeys$new()

Returns

empty (JoinKeys)

Method split()

Split the current JoinKeys object into a named list of join keys objects with an element for each dataset

Usage 

JoinKeys$split()

Returns

(list) a list of JoinKeys object

Method merge()

Merging a list (or one) of JoinKeys objects into the current JoinKeys object

Usage 

JoinKeys$merge(x)

Arguments

x

list of JoinKeys objects or single JoinKeys object

Returns

(self) invisibly for chaining

Method get()

Get join keys between two datasets.

Usage 

JoinKeys$get(dataset_1, dataset_2)

Arguments

dataset_1

(character) one dataset name

dataset_2

(character) other dataset name

Details

if one or both of dataset_1 and dataset_2 are missing then underlying keys structure is returned for further processing

Returns

(character) named character vector x with names(x) the columns of dataset_1 and the values of (x) the corresponding join keys in dataset_2 or character(0) if no relationship

Method mutate()

Change join_keys for a given pair of dataset names (or add join_keys for given pair if it does not exist)

Usage 

JoinKeys$mutate(dataset_1, dataset_2, val)

Arguments

dataset_1

(character) one dataset name

dataset_2

(character) other dataset name

val

(named character) column names used to join

Returns

(self) invisibly for chaining

Method set()

Set up join keys basing on list of JoinKeySet objects.

Usage 

JoinKeys$set(x)

Arguments

x

list of JoinKeySet objects (which are created using the join_key function) or single JoinKeySet objects

Details

Note that join keys are symmetric although the relationship only needs to be specified once

Returns

(self) invisibly for chaining

Method print()

Prints this JoinKeys.

Usage 

JoinKeys$print(...)

Arguments

...

additional arguments to the printing method

Returns

invisibly self

Method clone()

The objects of this class are cloneable with this method.

Usage 

JoinKeys$clone(deep = FALSE)

Arguments

deep

Whether to make a deep clone.

Examples 

x <- teal.data:::JoinKeys$new()
x$set(
  list(
    join_key("dataset_A", "dataset_B", c("col_1" = "col_a")),
    join_key("dataset_A", "dataset_C", c("col_2" = "col_x", "col_3" = "col_y"))
  )
)
x$get()
#> $dataset_A
#> $dataset_A$dataset_B
#>   col_1 
#> "col_a" 
#> 
#> $dataset_A$dataset_C
#>   col_2   col_3 
#> "col_x" "col_y" 
#> 
#> 
#> $dataset_B
#> $dataset_B$dataset_A
#>   col_a 
#> "col_1" 
#> 
#> 
#> $dataset_C
#> $dataset_C$dataset_A
#>   col_x   col_y 
#> "col_2" "col_3" 
#> 
#> 
x$mutate("dataset_A", "dataset_B", c("col1" = "col10"))
x$get("dataset_A", "dataset_B")
#>    col1 
#> "col10"