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Fitting data for each row of a matrix

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Nikolas Spiliopoulos
编辑： Daniela Conforti 2019-1-16
Hi there,
I have a matrix 8760x8 and I would like to fit the data of each row (8 values) with a vector like this: [1 2 3 4 5 6 7 8]
Is it possible to do it ?
thanks
  1 个评论
Stephen23
Stephen23 2017-6-27
@Nikolas Spiliopoulos: and what is the expected output of this "fitting"?

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回答（1 个）

dpb
dpb 2017-6-27
编辑：dpb 2017-6-27
Guessing the intent Stephen has asked for,
x=1:8; % the independent variable vector
nrow=size(data,1); % rows in data array (8760 but don't use "magic numbers)"
coeff=zeros(nrow,2); % preallocate for the coefficient array
for ix=1:nrow
coeff(ix,:)=polyfit(x,data(ix,:),1); % coefficients of linear fit on each row
end
See
doc polyfit
doc polyval
for details on them. Could also use fit if have Curve Fitting TB and return a fit object containing the coefficients and other info as alternative. If do go this route will have to pass x,row vector as columns.
None of the fitting tools are fully vectorized to do the fit on an array of columns so do need to iterate over the array.
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dpb
dpb 2017-6-27
Typo --
coeff(ix,:)=polyfit(x,annual_temperature_data(ix,:),1);
i is the Matlab builtin sqrt(-1).
Daniela Conforti
Daniela Conforti 2019-1-16
编辑：Daniela Conforti 2019-1-16
Hi, you know how can I use "polyfit" whitout using a for-loop?
I have the same problem described in this question but I'm using a matrix with millions of rows, therefore it requires a lot of time.

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