array manipulation - a few basic questions
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Hi, I have to do a bit of array manipulation and I really don't have a clue about it.
First I need to know how to take a double array, and turn it in to a 2046x1 array (twice as long), with 1024-2046 just being exactly the same as 1-1023.
Then I need to know how to chop off the first half of an array, in this case taking a 2046x1 array and disregarding the first 1-1023, leaving only a 1023x1 array made up from only the second half of the 2046x1 array.
I know it's simple stuff, but I just haven't done it before.
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Matt Fig
2012-11-2
Tom's question
Hi, I have to do a bit of array manipulation and I really don't have a clue about it.
First I need to know how to take a double array, and turn it in to a 2046x1 array (twice as long), with 1024-2046 just being exactly the same as 1-1023.
Then I need to know how to chop off the first half of an array, in this case taking a 2046x1 array and disregarding the first 1-1023, leaving only a 1023x1 array made up from only the second half of the 2046x1 array.
I know it's simple stuff, but I just haven't done it before.
采纳的回答
Rick Rosson
2012-3-19
Please try:
x = rand(1023,1);
y = repmat(x,2,1);
z = y(1024:2046);
HTH.
Rick
6 个评论
Jan
2012-3-19
Or: y = [x; x];
or: y = vertcat(x, x);
Rick Rosson
2012-3-19
Or: z = y(1024:end);
Jan
2012-3-19
I avoid the END in indexing expressions in general. There have been several bugs in nested expressions and it is "slower" than "1024:numel(y)" - if one could claim that micro-seconds matter.
Tom
2012-3-19
Tom
2012-3-19
Rick Rosson
2012-3-19
Yes, at least in this particular case, but not generally.
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