CODEWITHSUNDEEP
listsortingtcl
Lumpi
Lumpi

Reputation: 2821

Find the max absolute value of values in a dict using TCL

I have a list eg MyList 

 set MyList [ list 508 1.648E-01 509 1.670E-01 510 1.701E-01 511 1.740E-01 512 1.784E-01 ]

How can I extract the Key / Value pair where: The absolute value of the values is max within the list ?? (What a sentence...)

In this case 512 1.784E-01

I would create a foreach loop and save the key value whenever the abs(Value) is greater than the previous pair. Is there a method without a loop? Im on tcl 8.5 so the "lsort -stride" trick is out of reach.

Upvotes: 2

Views: 2487

Answers (2)

Donal Fellows
Donal Fellows

Reputation: 137717

The straight-forward way is to use dict for to do a classic iterate-over-collection with the dictionary.

set maxVal -Inf
dict for {k v} $MyList {
    if {$v > $maxVal} {
        set maxKey $k
        set maxVal $v
    }
}

The -Inf? A numeric value smaller than every other value. (IEEE arithmetic is great sometimes.)

Upvotes: 2

glenn jackman
glenn jackman

Reputation: 247022

I would create a new list containing key/value sublists

foreach {k v} $MyList {lappend newlist [list $k $v]}

Then use 

lassign [lindex [lsort -real -index 1 $newlist] end] max_key max_val

Upvotes: 1

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