Printing Lists and Iterators
Printing selected items The functions described here print lists or objects with an iterator with one item per line, either the whole list/iterator or certain subsets: by giving a list of positions of items to be printed, or by specifying a first item and then a regular step. This function, given three (or four) parameters, calls operations PrintSelectionFromList or PrintSelectionFromIterator which prints the first item specified, and then the item at every step. The fourth parameter is essential when the object being printed is infinite.

Alternatively, given two parameters, with the second parameter a list L of positive integers, only the items at positions in L are printed.

gap> L := List( [1..20], n -> n^5 );; gap> PrintSelection( L, [18..20] ); 18 : 1889568 19 : 2476099 20 : 3200000 gap> PrintSelection( L, 2, 9 ); 2 : 32 11 : 161051 20 : 3200000 gap> PrintSelection( L, 2, 3, 11 ); 2 : 32 5 : 3125 8 : 32768 11 : 161051 gap> s5 := SymmetricGroup( 5 );; gap> PrintSelection( s5, [30,31,100,101] ); 30 : (1,5)(3,4) 31 : (1,5,2) 100 : (1,4,3) 101 : (1,4)(3,5) gap> PrintSelection( s5, 1, 30 ); 1 : () 31 : (1,5,2) 61 : (1,2,3) 91 : (1,3,5,2,4) gap> PrintSelection( s5, 9, 11, 43 ); 9 : (2,5,3) 20 : (2,4) 31 : (1,5,2) 42 : (1,5,2,3,4)