DataSailr in 5 minutes or less

This file is autogenerated from README in DataSailr Github

Quick introduction

In this quick introduction, built-in R dataframe called mtcars is going to be used. The mtcars datafram has automobile information in 1970's. The detail of this dataframe is described here. (https://www.rdocumentation.org/packages/datasets/versions/3.6.1/topics/mtcars)

• Built-in dataframe, mtcars.

data(mtcars)
head(mtcars,2)

(OUTPUT)

	mpg	cyl	disp	hp	drat	wt	qsec	vs	am	gear	carb
Mazda RX4	21	6	160	110	3.9	2.620	16.46	0	1	4	4
Mazda RX4 Wag	21	6	160	110	3.9	2.875	17.02	0	1	4	4

Code example

Before executing the following code, install DataSailr package (and magrittr package.) Installation instruction is mentioned later in this README (Binary package is the easiest way to try, until this package becomes available on CRAN).

• (Example)

library(datasailr)
library(magrittr)

mtcars %>% datasailr::sail('
if( hp > 145 ){  power = "high" }
else if( 145 >= hp && hp > 0){ power = "low" }
else{  print("hp variable has missing value")}

germany = re/(^Merc|^Porsche|^Volvo)/
usa = re/(^Hornet|^Cadillac|^Lincoln|^Chrysler|^Dodge|^AMC|^Camaro|^Chevrolet|^Pontiac|^Ford)/
japan = re/(^Mazda|^Datsun|^Honda|^Toyota)/

if ( _rowname_ =~ germany ) { country = "Germany" ; type = rexp_matched(1); }
else if( _rowname_ =~ usa ) { country = "USA"  ; type = rexp_matched(1);  }
else if( _rowname_ =~ japan ) { country = "Japan"  ; type = rexp_matched(1); }
else { country = "Other" }
') %>% head(10)

• (OUTPUT)

	power	country	type
1	low	Japan	Mazda
2	low	Japan	Mazda
3	low	Japan	Datsun
4	low	USA	Hornet
5	high	USA	Hornet
6	low	Other
7	high	Other
8	low	Germany	Merc
9	low	Germany	Merc
10	low	Germany	Merc

Example code explanation

• library(datasailr)
  • Make DataSailr package available.
• library(magrittr)
  • This is not required by DataSailr. In the above code, %>% , pipe operator, is used, and it's defined in magrittr package.
• mtcars %>% datasailr::sail(' ....
  • The 1st argument of datasailr::sail is dataframe. In this case, %>% passes dataframe to the 1st argument.
  • The 2nd argument of datasailr::sail is DataSailr code.
• if( hp > 145 ){ ....
  • if-else statement.
• power = "high"
  • assign "high" to power column.
• germany = re/(^Merc|^Porsche|^Volvo)/
  • Regular expression literal is re/pattern/ .
• if ( _rowname_ =~ germany ){ ....
  • string =~ regular expression executes regular expression matching.
  • _rowname_ column is one of automatic variables. This holds the row names of the original R dataframe.
• rexp_matched(1)
  • Calling function of rexp_matched()
  • Extract the 1st matching group from the last regular expression matching.