tcl - Get items in specific index list of lists

Question

I have a key-value list such as:

set x {{a 1} {b 2} {c 3}}

I need to extract all the items in index=1 in all sub-lists to get:

{1 2 3}

Answer 1

You can use this:

$ set y {}
$ foreach sublist $x { lappend y  [lindex $sublist 1]}
$ puts $y
1 2 3

A solution for TCL 8.6 or newer:

Use lmap to iterate through x without saving value anywhere ,in one-line:

$ lmap sublist $x {lindex $sublist 1}

References: lmap,tcl.tk