bit library support - logical TRUE/FALSE data type without NA, reduced size

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#1,890 3 comments 3 reactions 0 assignees View on GitHub

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Assessment

Difficulty
5/5
Estimated time
Over a week
Newbie friendliness
25/100
Issue type
Feature
Clarity
Needs clarification
Activity status
Stale
Tech stack
r
Domain
data

Research direction

No files, tests, or entry points are named. Start by reproducing the R example with bit and data.table, then inspect how data.table currently stores and processes logical columns. Done would require an agreed design and tests showing support for a compact TRUE/FALSE representation without NA.

Written by the indexing model from the issue text.

Description

performance

Hi,

this issue is related to R internal data type used by data.table... Maybe there is a possibility to help reduce size of large size data.table with many T/F observation ?
More about bit support & logical size you can find at: http://stackoverflow.com/questions/9178254/why-do-logicals-booleans-in-r-require-4-bytes

library("bit")
library("data.table")
set.seed(42)
dt <- data.table(a=sample(c(10,20,25,30,40),100,replace=TRUE),b=1:100)
dt[,Logical:=ifelse(a>10,TRUE,FALSE)]
dt[,bitLogical:=as.bit(Logical)]
dt

output:

    a   b Logical bitLogical
  1: 40   1    TRUE  -19005569
  2: 40   2    TRUE  -37749781
  3: 20   3    TRUE -159552707
  4: 40   4    TRUE         15
  5: 30   5    TRUE  -19005569
  6: 25   6    TRUE  -37749781
  7: 30   7    TRUE -159552707
Dominant language
R
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