Pomocníci pro filtrování

Manipulace s daty pomocí data.table v R

Matt Dowle and Arun Srinivasan

Instructors, DataCamp

%like%

%like% umožňuje vyhledávat vzor ve vektoru typu character nebo factor
- Použití: col %like% pattern

# Subset all rows where start_station starts with San Francisco
batrips[start_station %like% "^San Francisco"]

# Instead of 
batrips[grepl("^San Francisco", start_station)]

%between%

%between% umožňuje vyhledávat hodnoty v uzavřeném intervalu [val1, val2]
- Použití: numeric_col %between% c(val1, val2)

# Subset all rows where duration is between 2000 and 3000
batrips[duration %between% c(2000, 3000)]

# Instead of 
batrips[duration >= 2000 & duration <= 3000]

%chin%

%chin% je podobné %in%, ale výrazně rychlejší a pouze pro znakové vektory
- Použití: character_col %chin% c("val1", "val2", "val3")

# Subset all rows where start_station is 
# "Japantown", "Mezes Park" or "MLK Library"
batrips[start_station %chin% c("Japantown", "Mezes Park", "MLK Library")]

# Much faster than
batrips[start_station %in% c("Japantown", "Mezes Park", "MLK Library")]

Pojďme si procvičit!

Manipulace s daty pomocí data.table v R