splitting arrays

[LSASS]

Hello everyone!!!

I have a problem: I have a huge 1D array and I need to split it in to sets of 8 elements as need to compare these 8 elements with another  1 D array of size 8. is this possible?

Thanks for the help!!

[MattBradley]

Try the Decimate 1 D array.  Read the help to see if it does what you want.

[Harold_Timmis]

use the split 1-D array function in the functions palette

[LSASS]

Hello again.. But the size of my 1D array can be unknown and I wouldn't know how many sets of 8 I would have 2 divide it in to. What will  I pass in to the index input of the split 1D array function?

[smercurio_fc]

Two straightforward ways (among others):

• Run a for-loop based (size of your array)/8 and then inside the loop use Array Subset to get each chunk of 8 elements. The comparison is done inside the loop.
• Use Reshape Array to reshape your 1D array into a 2D array that has 8 columns. The number of rows would be (size of your array)/8. Then auto-index a for-loop to pull off each row. The comparison is done inside the loop.

Is the input array guaranteed to have a length that is a multiple of 8? If it's not, what are you supposed to do?

Message Edited by smercurio_fc on 05-07-2009 09:01 PM

[Harold_Timmis]

use a for-loop

[LSASS]

 Yes the input array is a multiple of 8. thanks for the suggestions. ill give it a go:)

[MattBradley]

Still think decimating would be easier, but that's JMHO.

Here's why: (Assume N pts)

Decimate (add outputs until you have 8 outputs total).

Now, the outputs will be 8 size N/8 arrays.

Next, concatenate them back together.  Now you have a 2-D (8 x N/8) array.

Transpose it if you need it the other way around, and you're done.

[smercurio_fc]

True, but using Reshape Array allows you to do the same thing without having to hard-code the dimensions (i.e., the size of the Decimate and Build Array functions). The inputs to Reshape Array can be calculated using Array Size and the Quotient & Remainder function. More scalable.

[LSASS]

Hello smercurio,

I am usind the Array subset to split my huge 1D array in to chunks of 8. But I am unsure as to what to pass in to the index input of the Array subset function. When I put it in a for loop, the index continuously changes. So what do I input?

Thanks!!