assign a key value list to an array in Tcl - tcl

Question

I have a list that is a key value paired list. Something like the following
key1 value1 key2 value2 key3 value3
I would like to map this to an array or a dictionary.
Currently, my code looks like this
for {set i 0} {$i < [llength $list]} {incr i} {
if {[expr {fmod($i,2)}] == 0} {
set key [lindex $list $i]
} else {
set v_array(${key}) [lindex $list $i]
}
}
In perl, I know this can be assigned into a key value dictionary in one pass. Is there such simpler method in Tcl?

Answer 1

You can create an array in one line (I'm using one line to define the list):
% set list [list key1 value1 key2 value2 key3 value3]
key1 value1 key2 value2 key3 value3
% array set v_array $list
And if you want to check the contents, you can use parray (Tcl 8.5 and later):
% parray v_array
v_array(key1) = value1
v_array(key2) = value2
v_array(key3) = value3
And the documentation for the other array commands can be found here with examples for each.
If you somehow cannot avoid a loop, then using foreach would be easier (be sure the list has an even number of elements):
foreach {a b} $list {
set v_array($a) $b
}
(Here foreach is taking the elements in $list two at a time and assign them to a and b)

Answer 2

You can use dict command for creating/manipulating dictionaries in Tcl.
% set mydict [dict create key1 value1 key2 value2 key3 value3]
key1 value1 key2 value2 key3 value3
% dict get $mydict
key1 value1 key2 value2 key3 value3
% dict get $mydict key3
value3
% dict get $mydict key1
value1
%
Even without the dict create command, you can straightway fetch/access the keys and values even from a list as long as it is in key-value form. i.e. even number of elements.
For example,
% set mylist {key1 value1 key2 value2 key3 value3}
key1 value1 key2 value2 key3 value3
% dict get $mylist key2
value2
As you can notice, I have not used dict create command here , but still able to access the dictionary items.
Reference : dict

Answer 3

Easiest solution:
set mylist {key1 value1 key2 value2 key3 value3}
array set arr $mylist
Thats it.
Now, do a parray to check.
file: t3
#
set list [list key1 value1 key2 value2 key3 value3]
array set arr $list
parray arr
#
Execute the file: tclsh t3
arr(key1) = value1
arr(key2) = value2
arr(key3) = value3