Presentation from Moscow Data Fest #1, September 12. Moscow Data Fest is a free one-day event that brings together Data Scientists for sessions on both theory and practice. Link: http://www.meetup.com/Moscow-Data-Fest/

1. Alex Natekin
Deloitte Analytics Institute

2. 2
Been there, done that
natekin@dmlabs.org
vk.com/natekin
linkedin.com/in/natekin
facebook.com/alex.natekin

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Data.table

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Legend says
And many others…
“the R god of number crunching”

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Legend says (2)
… to read the manual
With great poweR comes great Responsibility
of fasteR & richeR
data crunching …

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Choose your side
dplyr sqldfdata.table
“Hadleyverse” Way of the warrior…
…each one is way different from data.frame

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Choose your side… wisely
from recent Matt
Dowle’s meetup
presentations

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from recent Matt
Dowle’s meetup
presentations
…just search for “data.table benchmarks”
Choose your side… wisely (2)

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data.table applicability
Solution
Data
extraction &
checks
Data
processing
Feature
engineering
Models Stories
…trying to find your place under the sun

10. 10
data.table applicability
Solution
Data
extraction &
checks
Data
processing
Feature
engineering
Models Stories
Naïve
functionality
Most awesome
functionality
Is closest to
production code
(if applicable to R)

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Core functionality
1. Data reading & memory
management
2. Data access & ordering
3. Grouping & aggregation
…
feature engineering
More efficient:

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Core functionality (2)
1. Data reading & memory
management
2. Data access & ordering
3. Grouping & aggregation
…
feature engineering
More efficient:
…as data.frame extension (~100% compatible)
1. Reduce
machine time
2. Reduce human
programming
time

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Core principle
DT[i, j, by]
1. Take DT
2. Subset rows by i
3. Calculate j
4. …grouped by by

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Core principle (2)
from data.table
tutorial

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Example: churn
Sorry
Laptop died last
evening,
no interactive
tutorial 
Screenshots
from remaining
files

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Example

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Example

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Example

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Example (manual injection)
setkey(DT, colA, colB)
Yet another
recent Matt
Dowle’s meetup
presentations

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Example

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Example

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Example

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Example

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Example

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Example

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Example: churn

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Example: churn

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Example: churn

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Example: churn

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Example: churn

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Functionality: more
1. Fread
2. Column updates
3. Set functions (set, setnames, …)
4. Special symbols (.SD, .I, …)
5. Joins
… next time 

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More: resources

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SummaRy
1. data.table is helpful & awesome
2. go forth and use it
3. RTFM

34. Thanks!
Alex Natekin
anatekin@deloitte.ru
+7 915 070 45 74