reshaping data properly mesh grid

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federico nutarelli
federico nutarelli 2021 年 5 月 5 日
Hi all,
so I have the follwoing problem. I have data stored in a (2000,4) mattrix where the last colum represents the predictions I drew from a logistic regression. Now, I managed to put in a messhgrid data on columns 2 and 3 (first term is the constant) as height and weeightt as follows:
h = min(X(:,1)):.01:max(X(:,1)); %(1,2069)
w = min(X(:,2)):1:max(X(:,2)); %(1,24)
[hx, wx] = meshgrid(h,w); %(24,2069)
but did not manage to put in the same form the predictions since I computed in a later step. Predictions are a (2000,1) vector.
The aim basically is to make this:
pred = reshape(pred, size(hx));
work without the error:
Error using reshape
Number of elements must not change. Use [] as one of the size inputs to automatically calculate the appropriate size
for that dimension.
which, if I have undestood the issue is solved if I manage to put pred in a vector of size "size(hx, 1) * size(hx, 2)".
Can you pleasse help m out on this?


KSSV 2021 年 5 月 5 日
Let X be your data matrix of size 2000*4.
h = X(:,2) ;
w = X(:,3) ;
nh = length(unique(h)) ;
nw = length(unique(w)) ;
h = reshape(h,nh,nw) ;
w = reshape(w,nh,nw) ;
p = reshape(X(:,4),nh,nw) ;
If the above works, it is good. If not have a look on griddata function. If not attach your data.
  6 件のコメント
federico nutarelli
federico nutarelli 2021 年 5 月 5 日
It works!


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