added condition

Author: venom1204

R/print.data.table.R

@@ -141,6 +141,8 @@ print.data.table = function(x, topn=getOption("datatable.print.topn"),
     print_default(toprint)
     return(invisible(x))
   }
+  if (col.names == "none")
+  colnames(toprint) = rep.int("", ncol(toprint))
   if (nrow(toprint)>20L && col.names == "auto")
     # repeat colnames at the bottom if over 20 rows so you don't have to scroll up to see them
     #   option to shut this off per request of Oleg Bondar on SO, #1482

inst/tests/tests.Rraw

@@ -21358,3 +21358,11 @@ test(2327.1, cube(DT, .(min(value)), "var"),
 test(2327.2, cube(DT, .(as.numeric(base::min(value, na.rm=TRUE))), "var"),
      data.table(var = c("a", "b", "c", "d", NA), V1 = c(1.0, 2.0, 3.0, Inf, 1.0)),
      warning="no non-missing arguments to min")
+
+#6882 print() output with col.names="none"
+dt = data.table(short = 1:3, verylongcolumnname = 4:6)
+test(2328.1, print(dt, col.names = "none"), output = "1: 1 4\n2: 2 5\n3: 3 6\n")
+dt = data.table(x = 123456, y = "wide_string")
+test(2328.2, print(dt, col.names = "none"), output = "1: 123456 wide_string\n")
+dt = data.table(a = NA_integer_, b = NaN)
+test(2328.3, print(dt, col.names = "none"), output = "1: NA NaN\n")