r - apply prepends space for logical -

having strange issue here apply , r 3.0.1.

i have huge dataframe text, numbers , logical values. logical values converted chr when use apply, because r allows true == "true" isn't problem.

but logical values, apply seems prepend space, , true == " true" returns na. of course, do

sapply(cuelist[,4],fun=function(logicalvalue) as.logical(sub("^ +", "", logicalvalue))) 

but isn't nice , still don't know why r that.

df <- data.frame(test=c("a","b","<",">"),logi=c(true,false,false,true)) apply(df, margin=1, function(listelement) print(listelement) ) 

interestlingly, spaces appear in example on [2,1] , [2,4]

version _
platform x86_64-w64-mingw32
arch x86_64
os mingw32
system x86_64, mingw32
status
major 3
minor 0.1
year 2013
month 05
day 16
svn rev 62743
language r
version.string r version 3.0.1 (2013-05-16) nickname sport

edit: same behaviour on r version 2.15.0 (2012-03-30)

edit2: dataframe lools this

> df   test  logi 1    false 2    b false 3    <  true 4    >  true  > str(df) 'data.frame':   4 obs. of  2 variables:  $ test: factor w/ 4 levels "<",">","a","b": 3 4 1 2  $ logi: logi  false false true true 

in way, problem apply, more appropriately, problem as.matrix, , how handling logical values.

here few examples elaborate on query had karl.

first, let's create 4 data.frames tests on.

1. your original data.frame demonstrate behavior:
2. a data.frame varying number of characters in "test" column karl's explanation of what's going on.
3. a data.frame numbers start understand seems going on.
4. a data.frame "logi" column explicitly created as.character.

df1 <- data.frame(test = c("a","b","<",">"),                   logi = c(true,false,false,true)) df2 <- data.frame(test = c("aa","b","<",">>"),                    logi = c(true,false,false,true)) df3 <- data.frame(test = c("aa","b","<",">>"),                    logi = c(true,false,false,true),                   num = c(1, 12, 123, 2)) df4 <- data.frame(test = c("aa","b","<",">>"),                    logi = as.character(c(true,false,false,true))) 

now, let's use as.matrix on each of them.

this has space before true.

as.matrix(df1) #      test logi    # [1,] "a"  " true" # [2,] "b"  "false" # [3,] "<"  "false" # [4,] ">"  " true" 

this has space before true, "test" column remains unaffected. hmm.

as.matrix(df2) #      test logi    # [1,] "aa" " true" # [2,] "b"  "false" # [3,] "<"  "false" # [4,] ">>" " true" 

ahh... has space before true and spaces before shorter numbers. seems perhaps r considering numeric underlying value of true , false, calculating width of number of characters in true , false. again, first "test" column remains unaffected.

as.matrix(df3) #      test logi    num   # [1,] "aa" " true" "  1" # [2,] "b"  "false" " 12" # [3,] "<"  "false" "123" # [4,] ">>" " true" "  2" 

things seem fine here, if tell r logi column character column.

as.matrix(df4) #      test logi    # [1,] "aa" "true"  # [2,] "b"  "false" # [3,] "<"  "false" # [4,] ">>" "true"  

for it's worth, sapply doesn't seem have problem.

sapply(df1, as.matrix) #      test logi    # [1,] "a"  "true"  # [2,] "b"  "false" # [3,] "<"  "false" # [4,] ">"  "true"  

---

update

in r public chat room, joshua ulrich points format being culprit. as.matrix uses as.vector factors, converts them character (try str(as.vector(df1$test)) see mean; else, uses format, unfortunately, doesn't have option include of arguments format, 1 of trim (which default set false).

compare following:

a <- c(true, false)  format(a) # [1] " true" "false" format(a, trim = true) # [1] "true"  "false" format(as.character(a)) # [1] "true " "false" format(as.factor(a)) # [1] "true " "false" 

---

so, how sort of convert logical columns character? maybe (though suggest creating backup of data first):

df1[sapply(df1, is.logical)] <- lapply(df1[sapply(df1, is.logical)], as.character) df1 #   test  logi # 1     true # 2    b false # 3    < false # 4    >  true as.matrix(df1) #      test logi    # [1,] "a"  "true"  # [2,] "b"  "false" # [3,] "<"  "false" # [4,] ">"  "true"