Using repeat loop to add values

[Josh1910]

I feel like I knew this at one point, but I've lost it. Long story short, I wanted to add values in an array together, so something like this:

repeat with z=1 to thisNum
add Numb&z tempSum
end repeat

The problem is that it tries to add "Numb1" instead of the value in the container Numb1. I did it a dreadful way as follows (only because I'm pressed for time):

repeat with z=1 to thisNum
if z =1 then add Numb1 to tempSum
if z =2 then add Numb2 to tempSum
if z =3 then add Numb3 to tempSum
if z =4 then add Numb4 to tempSum
if z =5 then add Numb5 to tempSum
if z =6 then add Numb6 to tempSum
if z =7 then add Numb7 to tempSum
if z =8 then add Numb8 to tempSum
if z =9 then add Numb9 to tempSum
end repeat

But I know that's an inefficient approach. What is the solution?

Would it be:

repeat with z=1 to thisNum
add Numb[z] to tempSum
end repeat

Any help would be appreciated in my future programming. Thanks!

[Klaus]

Hi Josh,

this is a job for DO!

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...
repeat with z = 1 to thisNum
   do("add Numb" & z && "to tempSum")
end repeat
...

However for these kind of situations you should consider to use a numbered ARRAY
instead of lots of single variables, where you can loop through the keys easily!

Best

Klaus

[bogs]

I thought for adding arrays, it would be more like (not tested)

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repeat for each element x in [arrayName]
   add x to tempSum
end repeat

but I could be off. And Klaus posted as I was heh.

[dunbarx]

Hi.

You do not really have an array. I think. This is a very special LC variable, and we can discuss it later. In the meantime, consider this in a button script:

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on mouseUp
   put 1 into numb1
   put 2 into numb2
   put 3 into numb3
   put 4 into numb4
   
   repeat with z = 1 to 4
      do "get numb" & z
      add it to tempSum
   end repeat
   answer tempSum
end mouseUp

The ability to evaluate an expression to two levels is required for the sort of construction you created. The "do" command evaluates the expression and then "executes" it. In that evaluation, the concatenation of the string "numb" with the variable "z' takes place, so that the final "add" line makes sense to LC.

There are other ways to do what you are working with, but we can discuss that later as well.

Craig Newman

[dunbarx]

Hi.

Klaus' construction is the same as mine, but more compact. Do you see how both versions take a string and "evaluate" it twice?

For Klaus, the parenthesis comprises a level of evaluation, and the "do" does it yet again. In mine, perhaps more readable , each line evaluates on its own.

It is not obvious why LC (and HC before it, where this all first came up) cannot "read" the statement:

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add "numb" & z to tempSum
or even:
add ("numb" & z) to tempSum

in one pass. but it cannot.

Craig

[[-hh]]

Yet another option: Use sum().

(a) if each of the 9 numX is a number:

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put sum(num1,num2,num3,num4,num5,num6,num7,num8,num9) into tempsum

(b) if numArray is an array containing only numbers (no matter the keys):

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put sum(numArray) into tempsum

[SparkOut]

The cat is losing skin alarmingly!
Another approach:

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   repeat with i = 1 to thisNum
      add value("Numb" & i) to tTempSum
   end repeat

[FourthWorld]

But I know that's an inefficient approach. What is the solution?

Would it be:

Code: Select all

     repeat with z=1 to thisNum
         add Numb[z] to tempSum
      end repeat

Yes.

Or Bogs' variant above which uses "repeat for each element...", which will execute slightly faster.

[bogs]

which will execute slightly faster.

Heh, I wonder how many iterations you'd have to have to notice it though. I would guess several hundred?

[FourthWorld]

which will execute slightly faster.

Heh, I wonder how many iterations you'd have to have to notice it though. I would guess several hundred?

Given how fast arrays are in general and the relatively small savings by using the "repeat for each element" option, depending on the size of the array (particularly the number of keys) you'd need at least many thousands of iterations to become measurable, and at least a hundred thousand or more to become noticeable.

[bogs]

Nice, but WOW was I off

[Mikey]

The cat is losing skin alarmingly!
Another approach:

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   repeat with i = 1 to thisNum
      add value("Numb" & i) to tTempSum
   end repeat

DANG IT! That was my first idea.

[bogs]

Don't worry Mikey, your not out yet, we're giving you a second chance !

Start skinning !

[[-hh]]

I really wonder why you are ignoring the wonderful super fast function sum()?

Instead of "add Numb[z] to tempSum", no matter whether using "repeat with" or "repeat for each",
if Numb is an array containing only numbers then the one-liner

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 put sum(Numb) into tempsum 

is, TMHO, "the" solution, directly given by the engine. No skinning needed, I like cats.

[Mikey]

Mmmmmmmm Kitty kabobs. Yum.