How to Retrieve array key values in Tcl

Question

Given Data

array set color {a red b green c blue}
set keylist [array names $color]
pointlist  {{1 2 3 4} {5 6 7 8} {9 10 11 12} {13 14 15 16}}

I get a new list after running a procedure.

 newlist  {b b b b}     # Note: length of newlist is same as length of pointlist

Question is : when i run a loop these values of b should be substituted, for example in this green.

for {set i 0} { $i < [llength $pointlist]} {incr i } {
    lassign [lindex $pointlist $i] x1 y1 x2 y2
    APICommand -points "$x1,$y1,$x2,$y2" -color $color($keylist)
}

Now this $color($keylist) is not getting me correct result and errors out saying : can't read "color(red blue green)": no such element in array

Instead I want the first set of 4 points to get the green color which is the value of b. Similarly next set of 4 points from pointlist should also get green as its value is also b.

 #So, after substitution it should look like APIcommand -points 1,2,3,4 -color green ..... so on and so forth

Note this will not always be b , it just happens to be in this case.

Need solution asap. Thanks in advance.

glenn jackman · Accepted Answer · 2013-12-05 20:56:09Z

1

Sounds like you need $color([lindex $newlist $i])

answered Dec 5, 2013 at 20:56

glenn jackman

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1 Comment

user2643899 Over a year ago

I was trying to use a foreach loop inside the for loop and then use -color [lindex $color($newlist) $i] and that is why it was giving me error. but using the array name first and then the index of keylist solved my problem. Thanks again !! (It's exactly what I was looking for )

andy mango · Accepted Answer · 2013-12-05 21:25:36Z

1

When iterating across a list, the foreach command is useful. It can also be used to iterate over multiple corresponding lists. Assuming newlist holds the colors that correspond to the points, I might try something like (usual warnings about untested code):

foreach point $pointlist new $newlist {
    APICommand -points [join $point ,] -color $color($new)
}

answered Dec 5, 2013 at 21:25

andy mango

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1 Comment

user2643899 Over a year ago

We dont have to calculate foreach point, we have to do this for group of 4 points. means 4 points corresponds to one color

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