How to extract every other value from a 50000x1 array?

Hello.

I have a problem I can't solve. I read in values over a serial COM port, the valuea are 12bit ADC results but I need to send them as:

 value = ADC_reading;
 Serial.write(value >> 8);
 Serial.write(value & 0xFF);

So when received in matlab its a stream of value pairs, for example:

2 251 2 251 2 251 2 251 2 251 2 251 2 251 2 251 2 251 2 251 2 251 2 251... though I store them as a n x 1 vector.

How can I process this vector?

I have been on the path of reading only one pair of values one byte at a time in some loop but that does not seem to be a good idea at all, I get problem when trying to solve the end value vector indexing.If there is no solution to this I 'could' send the values in its hole form but that will take at least 5 bytes per value and I am going out of my way to squeezing every little efficiency out of the setup in order to achieve as high a data throughput as possible.

Regards

Answer 1

[Chad Greene]

If I'm understanding your question correctly,

x = [2 251 2 251 2 251 2 251 2 251 2 251 2 251 2 251 2 251 2 251 2 251 2 251]; 
a = x(1:2:end) 
b = x(2:2:end)
a =
     2     2     2     2     2     2     2     2     2     2     2     2
b =
   251   251   251   251   251   251   251   251   251   251   251   251

[David]

Haha, I feel stupid having spent hours and hours and not figuring that out:)

Thank you so much.

[Chad Greene]

...that happens to all of us. :)

[Stephen23]

You mention efficiency of data processing: if the data is large, it may help to keep the data in the original array, and just reshape it:

>> x = [2 251 2 251 2 251 2 251 2 251 2 251 2 251];
>> reshape(x,2,[])
ans =
     2     2     2     2     2     2     2
   251   251   251   251   251   251   251

Of course this also depends on what processing follows on from this step...