So trennen Sie eine Zeichenkettenspalte basierend auf dem ersten Leerzeichen

Question

Dies sind meine Daten.

mtcars$brand=row.names(mtcars) 
    mtcars$brand 
    ## [1] "Mazda RX4"   "Mazda RX4 Wag"  "Datsun 710"   
    ## [4] "Hornet 4 Drive"  "Hornet Sportabout" "Valiant"    
    ## [7] "Duster 360"   "Merc 240D"   "Merc 230"   
    ## [10] "Merc 280"   "Merc 280C"   "Merc 450SE"   
    ## [13] "Merc 450SL"   "Merc 450SLC"   "Cadillac Fleetwood" 
    ## [16] "Lincoln Continental" "Chrysler Imperial" "Fiat 128"   
    ## [19] "Honda Civic"   "Toyota Corolla"  "Toyota Corona"  
    ## [22] "Dodge Challenger" "AMC Javelin"   "Camaro Z28"   
    ## [25] "Pontiac Firebird" "Fiat X1-9"   "Porsche 914-2"  
    ## [28] "Lotus Europa"  "Ford Pantera L"  "Ferrari Dino"  
    ## [31] "Maserati Bora"  "Volvo 142E" 

Ich möchte nur den ersten Namen der Marke (einen Teil bis zum ersten Leerzeichen) extrahieren

so - wie es zu tun

##        brand brand2 
## Mazda RX4     Mazda RX4  Mazda 
## Mazda RX4 Wag   Mazda RX4 Wag  Mazda 
## Datsun 710    Datsun 710  Datsun 
## Hornet 4 Drive  Hornet 4 Drive  Hornet 
## Hornet Sportabout Hornet Sportabout  Hornet 
## Valiant      Valiant  Valiant 
## Duster 360    Duster 360  Duster 
## Merc 240D     Merc 240D  Merc 
## Merc 230     Merc 230  Merc 
## Merc 280     Merc 280  Merc 

Dies sind die vier Möglichkeiten

> mtcars$brand2=gsub(" .*$", "",mtcars$brand) 
> mtcars$brand3=sapply(strsplit(mtcars$brand, "\\s+"), "[", 1) 

> mtcars$brand4=substr(mtcars$brand,1,regexpr(" ",mtcars$brand)) 
> mtcars$brand4=ifelse(mtcars$brand4=="",mtcars$brand,mtcars$brand4) 

library(stringr) 
> mtcars$brand5=str_extract(mtcars$brand, boundary("word")) 

Answer 1

strsplit

unlist(lapply(strsplit(rownames(mtcars)," "),function(x) x[1])) 

oder gsub

gsub("^([A-Za-z]+) .*","\\1",rownames(mtcars),perl=TRUE) 

Answer 2

Sie str_extract verwenden:

library("stringr") 
brand <- row.names(mtcars) 
str_extract(brand, boundary("word")) 
>[1] "Mazda" "Mazda" "Datsun" "Hornet" "Hornet" "Valiant" 
>[7] "Duster" "Merc"  "Merc"  "Merc"  "Merc"  "Merc"  
>[13] "Merc"  "Merc"  "Cadillac" "Lincoln" "Chrysler" "Fiat"  
>[19] "Honda" "Toyota" "Toyota" "Dodge" "AMC"  "Camaro" 
>[25] "Pontiac" "Fiat"  "Porsche" "Lotus" "Ford"  "Ferrari" 
>[31] "Maserati" "Volvo"