Examples/Arrow/JoinArrow.md

In WinVector/rquery: Relational Query Generator for Data Manipulation at Scale

JoinArrow

Converting a join to a an arrow (R version, Python version).

library(wrapr)
library(rquery)
library(rqdatatable)

d1 <- wrapr::build_frame(
   "key"  , "x" |
     "a"  , 1   |
     "b"  , 2   )

knitr::kable(d1)

| key | x | | :-- | -: | | a | 1 | | b | 2 |

table_1_description <- local_td(d1, name='d1')

table_1_description

## [1] "mk_td(\"d1\", c( \"key\", \"x\"))"

d2 <- wrapr::build_frame(
   "key"  , "y" |
     "b"  , 3   |
     "c"  , 4   )

knitr::kable(d2)

| key | y | | :-- | -: | | b | 3 | | c | 4 |

table_2_description <- local_td(d2, name='d2')

table_2_description

## [1] "mk_td(\"d2\", c( \"key\", \"y\"))"

ops <- table_1_description %.>%
    natural_join(.,
        b=table_2_description, 
        by='key',
        jointype='FULL')

arrow_1 = arrow(ops, free_table_key = table_1_description$table_name)

print(arrow_1)

## [
##  'd1':
##  c('key', 'x')
##    ->
##  c('key', 'x', 'y')
## ]

arrow_2 = arrow(ops, free_table_key = table_2_description$table_name)

print(arrow_2)

## [
##  'd2':
##  c('key', 'y')
##    ->
##  c('key', 'x', 'y')
## ]

res <- ex_data_table(
  arrow_1$pipeline,
  tables = list(
    d1 = d1,
    d2 = d2))

knitr::kable(res)

| key | x | y | | :-- | -: | -: | | a | 1 | NA | | b | 2 | 3 | | c | NA | 4 |

More on the categorical arrow treatment of data transformations can be found here.

(Examples of advanced inter-operation between the R rquery package and the Python data_algebra package and SQL can be found here.)

WinVector/rquery documentation built on Aug. 24, 2023, 11:12 a.m.