How do I remove duplicate arrays from an array?

MAXScript FAQ > MAXScript Values > How do I remove duplicate arrays from an array?

A user asked:

I've been trying to figure out how to do this for a while now, but I just can't get it. Here's the situation, let's say I have an array of arrays like this:

#(#(1, 5), #(6, 10), #(6, 10), #(14, 18), #(14, 18))

How can I search for, and get rid of, the duplicates, which in this case would be 2 & 3, and 4 & 5.

If I use find Item, it just returns the first instance and doesn't continue searching. I've also tried comparing the first and second numbers using nested 'for' loops, but I can't seem to set it up so that it works like I want. Mainly, there seem to be problems when deleting items from an array while it's going through a loop.

Answer:

Here is a long version with some debug prints so you can see what is happening.

The key is to always count BACKWARDS when deleting elements from an array you are looping through! Otherwise, the loop will get confused as deleting elements renumbers the array items.

LONG VERSION

(
theArray = #(#(1, 5), #(6, 10), #(6, 10), #(14, 18), #(14, 18))
print "Before:"
print theArray
fn compareSubArrays first second =
(
  result = true
  if first.count != second.count then
    result = false
  else
    for i = 1 to first.count do
  if first[i] != second[i] do result = false
  result
)
for i = 1 to theArray.count do
(
  for j = theArray.counttoi+1 by -1 do
  (
    format "Comparing %:% to %:% \n" i theArray[i] j theArray[j]
    test = (compareSubArrays theArray[i] theArray[j])
    print test
    if test do
    (
      deleteItem theArray j
      format"Deleting %\n"j
    )
  )--end j loop
)--end i loop
print"After:"
print theArray
)

RESULTS:

"Before:"
#(1, 5)
#(6, 10)
#(6, 10)
#(14, 18)
#(14, 18)
Comparing 1:#(1, 5) to 5:#(14, 18)
false
Comparing 1:#(1, 5) to 4:#(14, 18)
false
Comparing 1:#(1, 5) to 3:#(6, 10)
false
Comparing 1:#(1, 5) to 2:#(6, 10)
false
Comparing 2:#(6, 10) to 5:#(14, 18)
false
Comparing 2:#(6, 10) to 4:#(14, 18)
false
Comparing 2:#(6, 10) to 3:#(6, 10)
true
Deleting 3
Comparing 3:#(14, 18) to 4:#(14, 18)
true
Deleting 4
"After:"
#(1, 5)
#(6, 10)
#(14, 18)
OK
OK

COMPACT VERSION WITH COMMENTS:

(
theArray = #(#(1, 5), #(6, 10), #(6, 10), #(14, 18), #(14, 18))
--Function to compare the content of two arrays
fn compareSubArrays first second =
(
  result = true --init. return value to true
  if first.count != second.count then --if the count of the two subarrays is different,
    result = false--return false
  else --otherwise
    for i = 1 to first.count do --go through all elements in the arrays
  if first[i] != second[i] do result = false --and see if two elements are different
  result --return the result - true if identical, false if not
)
for i= 1 to theArray.count do --go through all elements of the main array
for j = theArray.count to i+1 by -1 do --go backwards from the last to the current+1
  if compareSubArrays theArray[i] theArray[j] do
    deleteItem theArray j --if identical, delete the one with the higher index
format "%\n" theArray --print the result to the Listener
)

RESULT:

#(#(1, 5), #(6, 10), #(14, 18))
OK
OK

How do I remove duplicate arrays from an array?

A user asked:

Answer:

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