store data in matrix

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paul kaam
paul kaam 2015-7-8
回答： Thorsten 2015-7-8
Hi everyone,
i am getting data every second that looks like this:
a =
Columns 1 through 8
223.5700 -0.0300 -0.0700 50.7000 1.0310 -0.1600 -0.1900 76.1000
Column 9
1.0420
this will go on for approximately 6 -7 hours. Now i want to store this in a matrix (so it grows), so after 3 second I have a matrix of 3 x 9. Unfortunately I am having difficulty realizing it.
could you help me out?
Many thanks
Paul
  1 个评论
Azzi Abdelmalek
Azzi Abdelmalek 2015-7-8
编辑：Azzi Abdelmalek 2015-7-8
How are you getting these data? how are they captured? are you using a Daq or just a code?

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回答（1 个）

Thorsten
Thorsten 2015-7-8
Growing matrices slow down your program, so preallocate M:
Nhours = 7;
M = ones(Nhours*3600, 9);
Have a look at it's size
whos M
Name Size Bytes Class Attributes
M 25200x9 1814400 double
1.8 MB, seems ok.
Now create an index for the row and increment i every second when you add a new value to M
i = 1;
% start you loop to get data
M(i,:) = currrentdata;
i = i + 1;

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