cdata

John Mount, Win-Vector LLC

2018-01-03

cdata is a demonstration of the “coordinatized data” theory and includes an implementation of the “fluid data” methodology. The tutorial of the general methodology is: Fluid data reshaping with cdata. Another example can be found here.

Briefly cdata supplies data transform operators that:

• Work on local data or any DBI data source.
• Are powerful generalizations of the operators commonly called pivot and un-pivot.

A quick example:

library("cdata")

## Loading required package: wrapr

my_db <- DBI::dbConnect(RSQLite::SQLite(), ":memory:")

# pivot example
d <- data.frame(meas = c('AUC', 'R2'), val = c(0.6, 0.2))
DBI::dbWriteTable(my_db,
                  'd',
                  d,
                  temporary = TRUE)
qlook(my_db, 'd')

## table `d` SQLiteConnection 
##  nrow: 2 
## 'data.frame':    2 obs. of  2 variables:
##  $ meas: chr  "AUC" "R2"
##  $ val : num  0.6 0.2

cT <- build_pivot_control_q('d',
                              columnToTakeKeysFrom= 'meas',
                              columnToTakeValuesFrom= 'val',
                              my_db = my_db)
tab <- blocks_to_rowrecs_q('d',
                            keyColumns = NULL,
                            controlTable = cT,
                            my_db = my_db)
qlook(my_db, tab)

## table `mvtcq_b3scgqeoozwcvgjsy28h_0000000001` SQLiteConnection 
##  nrow: 1 
## 'data.frame':    1 obs. of  2 variables:
##  $ AUC: num 0.6
##  $ R2 : num 0.2

DBI::dbDisconnect(my_db)

Note: cdata is targeted at data with “tame column names”, that is column names that are valid both in databases, and as R variable names.