Why do I get an error message when I pick a random item from a list?

Scripting Forums AppleScript | Mac OS X
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#1

I have this list:

property persons : {¬
	{fnamn:"Mary", lnamn:"E Neumann"}, ¬
	{fnamn:"Mark", lnamn:"Lance"}, ¬
	{fnamn:"Connie", lnamn:"Mey"}, ¬
	{fnamn:"Mary", lnamn:"E Neumann"}, ¬
	{fnamn:"Mark", lnamn:"Lance"}, ¬
	{fnamn:"Connie", lnamn:"Mey"}, ¬
	{fnamn:"Mary", lnamn:"E Neumann"}, ¬
	{fnamn:"Mark", lnamn:"Lance"}, ¬
	{fnamn:"Connie", lnamn:"Mey"}, ¬
	{fnamn:"Sara", lnamn:"Wern"}}

I want a random item from this list:

on getPerson(persons)
	if (count of persons) > 0 then
		set i to (random number from 1 to (count persons))
		set person to item i of persons

When the random number is 1 I get this error??

tell current application
	random number from 1 to 9
		--> 1
	(*Error: Can’t get items 1 thru 0 of {{fnamn:"Mary", lnamn:"E Neumann"}, {fnamn:"Mark", lnamn:"Lance"}, {fnamn:"Connie", lnamn:"Mey"}, {fnamn:"Mary", lnamn:"E Neumann"}, {fnamn:"Mark", lnamn:"Lance"}, {fnamn:"Connie", lnamn:"Mey"}, {fnamn:"Mark", lnamn:"Lance"}, {fnamn:"Connie", lnamn:"Mey"}, {fnamn:"Sara", lnamn:"Wern"}}. (-1728)*)

What does Can’t get items 1 thru 0 of mean?? Why “0”? Where does it come from?

I have tried this:


set i to (random number from 1 to 1)
set person to item i of persons

with the same list and it works every time.

#2

try this…

on getPerson(persons)
	local person
	if (count of persons) > 0 then
		set i to (random number from 1 to (count persons))
		set person to item i of persons
	end if
	return person
end getPerson
#3

I suggest you reduce your script to it’s minimal configuration that reporduces the error and post that.

I ran this from ScriptDebugger with no errors. So there seems to be some context that is interfering with your script.

property persons : {¬
	{fnamn:"Mary", lnamn:"E Neumann"}, ¬
	{fnamn:"Mark", lnamn:"Lance"}, ¬
	{fnamn:"Connie", lnamn:"Mey"}, ¬
	{fnamn:"Mary", lnamn:"E Neumann"}, ¬
	{fnamn:"Mark", lnamn:"Lance"}, ¬
	{fnamn:"Connie", lnamn:"Mey"}, ¬
	{fnamn:"Mary", lnamn:"E Neumann"}, ¬
	{fnamn:"Mark", lnamn:"Lance"}, ¬
	{fnamn:"Connie", lnamn:"Mey"}, ¬
	{fnamn:"Sara", lnamn:"Wern"}}

repeat 1000 times
	if (count of persons) > 0 then
		tell current application
			set i to (random number from 1 to (count persons))
			set person to item i of persons
		end tell
	end if
end repeat
1 Like
#4

Unless there’s a specific reason you want to generate a random number yourself, keep it simple:

to getRandomPerson from persons
        tell persons to if its class is in ¬
                [record, list] and it ≠ {} ¬
                then return some item
        missing value
end getRandomPerson

some item of... returns a random item from a list, record, or string. I recall reading somewhere (although I can’t remember where) that it results in a greater degree of randomness than the random number command, which may or may not be true.

1 Like
#5

The reason I use a random number/index is that I remove that entry from the list afterwards. Are there better ways?

#6

I have done that. I have tested with a minimal on run () handler that just initiates the list and call the getPerson () handler with the list.

#7

You still haven’t posted your entire script so we can see that’s going on.