x <- c(1,2,3)
y <- c("A","B","C")
x > 1
x < 3
y == "B"
x < 3 & y == "B"
x < 3 | y == "B"
paste( "My","name","is","mud.")
args( paste )
paste( "My","name","is","mud.", sep=":" )
paste( "My","name","is","mud.", sep="" )
paste0( "My","name","is","mud." )
a <- "mud."
a
paste("My","name","is", a ) # it can handle objects as arguments
b <- c("Larry","Moe","Curly")
b
paste("My","name","is", b ) # it is vectorized
data.frame( my="My", name="name", is="is", id=b ) 
data.frame( my="My", name="name", is="is", id=b ) 
paste( "id-", 1:10, sep="" )
c("This is a string.", "These", "words","are", "also", "strings." )
x <- c("This is a string.", "These", "words","are", "also", "strings." )
x
x
unlist( strsplit( x, " " ) )
unlist( strsplit( x, "" ) )
strsplit( x, " " )
unlist( strsplit( x, " " ) )
results <- strsplit( x, " " )
results
length( x )
results <- strsplit( x, " " )
length( results[[1]] )
length( results )
lapply( results, length )
unlist( lapply( results, length ) )
results <- strsplit( x, "" )
lapply( results, length )
library( dplyr )
lapply( results, length ) %>% unlist()
lapply( results, length )
z <- lapply( results, length )
z
z <- lapply( results, length ) %>% unlist()
z
rbind( x, z )
cbind( x, z )
z <- lapply( results, length )
word.count <- lapply( strsplit( x, " " ), length )
char.count <- lapply( strsplit( x, "" ), length )
d <- data.frame( string=x, wc=word.count, cc=char.count )
d
word.count <- lapply( strsplit( x, " " ), length ) %>% unlist()
char.count <- lapply( strsplit( x, "" ), length ) %>% unlist()
d <- data.frame( string=x, wc=word.count, cc=char.count )
d 
strings <- c("abcd", "cdab", "cabd", "c abd")
strings
grep( "ab", strings, value = TRUE )
grep("^ab", strings, value = TRUE)
grep("ab$", strings, value = TRUE)
grep("\\Bab", strings, value = TRUE)
gsub( "land", "LAND", c("finland", "iceland", "michael landon") )
gsub( "\\bland", "LAND", c("finland", "iceland", "michael landon") )
gsub( "land$", "LAND", c("finland", "iceland", "michael landon") )
grepl( "\\bab", strings )
grepl( "\\bab", strings ) %>% sum()
grepl( "\\bab", strings ) %>% mean()
strings
grep( "ab$", strings, value = FALSE )
strings <- c( "ht", "hot", "hoot", "hooot" )
grep("h*t", strings, value = TRUE)
grep("h.t", strings, value = TRUE)
grep("ho+t", strings, value = TRUE)
grep("h+ot", strings, value = TRUE)
grep("ho?t", strings, value = TRUE)
grep("ho{2}t", strings, value = TRUE)
grep("ho{2,}t", strings, value = TRUE)
grep("ho{1,2}t", strings, value = TRUE)
regexpr( "*", "abcd*efghi" )
grepl( "*", "abcd*efghi" )
grepl( "*", c("abcdefghi","abcd*efghi") )
grepl( "*", c("","abcdefghi","abcd*efghi") )
grepl( "\\*", c("","abcdefghi","abcd*efghi") )
my.text <- c( "FormA", "FormC", "FormE", "FormX", "FormY" )
grep( pattern="Form*", my.text )
grep( pattern="Form*", my.text, value=TRUE )
grep( pattern="Form[ABC]", my.text, value=TRUE )
my.text 
grep( pattern="Form[abc]", my.text, value=TRUE )
"a" == "A"
args( grep )
grep( pattern="Form[abc]", my.text, value=TRUE, ignore.case=TRUE )
grep( pattern="Form[ABCabc]", my.text, value=TRUE )
grep( pattern="Form[A-C]", my.text, value=TRUE )
my.text <- c( "FormA", "FormB", "FormE", "FormX", "FormY" )
grep( pattern="Form[A-C]", my.text, value=TRUE )
grep( pattern="h[oi]t" , c("hot","hat","hit","hop") )
grep( pattern="h[oi]t" , c("hot","hat","hit","hop"), value=TRUE )
grep( pattern="g*fy", my.text, value=TRUE )
my.text <- c("micky","minnie","goofy","gofy","pluto")
grep( pattern="g*fy", my.text, value=TRUE )
grep( pattern="pluo?to", my.text, value=TRUE )
grep( pattern="pluo?t", my.text, value=TRUE )
grep( pattern="plu?ot", my.text, value=TRUE )
grep( pattern="plo?to", my.text, value=TRUE )
grep( pattern="plu?o?to", my.text, value=TRUE )
grep( pattern="pl.to", my.text, value=TRUE )
my.text <- c("micky","minnie","goofy","gofy","pluto")
grep( pattern="g.fy", my.text, value=TRUE )
grep( pattern="g.{2}fy", my.text, value=TRUE )
grep( pattern="g.{1,}fy", my.text, value=TRUE )
grep( pattern="g.{,1}fy", my.text, value=TRUE )
grep( pattern="g*{,1}fy", my.text, value=TRUE )
grep( pattern="mi*", my.text, value=TRUE )
URL <- "https://raw.githubusercontent.com/DS4PS/cpp-527-fall-2020/master/labs/data/medium-data-utf8.csv"
d <- read.csv( URL )
grep( pattern="\\?", d$title, value=TRUE )
grep( pattern="\\?$", d$title, value=TRUE ) 
grep( pattern="\\B?", d$title, value=TRUE ) 
grep( pattern="\\B\\?", d$title, value=TRUE ) 
grep( pattern="\\B?", d$title, value=TRUE ) 
grep( pattern="\\B[?]", d$title, value=TRUE )