Does R automatically remove '.' from data.frame column names? -

does d1$patient....age = d1$patient....age ?

i'm guessing these simple concept causes behaviour. reliable behaviour predictable? ie: if name data.frame column a...b can references $a ?

the example provided in source doesn't explain i'm seeing in r.

from http://biostat.mc.vanderbilt.edu/wiki/pub/main/svetlanaedenrfiles/regexprtalk.pdf

d1 = data.frame(id...of....patient = c(1, 2), patient....age = c(3, 4)) d1$patient....age #[1] 3 4 d1$patient #[1] 3 4 d1$age #null d1$id...of....patient #[1] 1 2 d1$id #[1] 1 2 d1$id...of #[1] 1 2 names(id) #null names(d1) #[1] "id...of....patient" "patient....age" 

r's $ operator accepts unambiguous prefix of column name referring column. has nothing .s.

for example, try:

d1$id...of....patient # [1] 1 2 d1$id...of....pati # [1] 1 2 d1$id...o # [1] 1 2 

this true whether or not there dots in column name: mtcars$disp, mtcars$dis, , mtcars$di return disp column of mtcars dataset. (however, mtcars$d returns null, both disp , drat columns start d).