How do I remove duplicate arrays from an array?
A user asked:
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 does not continue searching.
I have also tried comparing the first and second numbers using nested 'for' loops,
but I cannot set it up to work like I want. Mainly, there seems to be problems when
deleting items from an array while it is 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 gets 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.count to i+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
|