How to align multiple tables/matrices based on the first column

DZ
2011 9 30
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Hello,
I am new to programming, and trying to write a script to align multiple 4-column tables based on the first column. The first column are numbers in the order from small to large(you may think it as date). The numbers may be slightly different from table to table, and some tables may have more rows than the others. In the script I wrote below, it covers 4 tables(A,B,C,D), and generate the aligned table A. I can repeat the codes to generated aligned table B, C, D as well. However, my problem is that the number of input tables may vary from 4 to 20, and I don't want to revise my script every time. I have not figured out how to write such a script. Any suggestions are appreciated.
The script is the following:
function z=align4(A, B, C, D, reslst) % align matrices A, B, C and D
if nargin<5, reslst=[]; end %default: all resid.
if isempty(reslst),
rlst=[min([A(:,1);B(:,1);C(:,1);D(:,1)]):max([A(:,1);B(:,1);C(:,1);D(:,1)])]'; % Generate a complete residue list.
else
rlst=reslst(:);
end
nres=length(rlst);
z=NaN*ones(nres,4);
z(:,1)=rlst;
for ii=1:nres,
indA=find(A(:,1)==rlst(ii));
if ~isempty(indA), z(ii,2:end)=A(indA,2:end); end
end
return

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Walter Roberson
Walter Roberson 2011-9-30
You have not defined what you mean by "align" for this purpose.
Do you mean something like a database "join" operation ? http://en.wikipedia.org/wiki/Join_%28SQL%29
DZ
DZ 2011-9-30
My case looks simpler but different. I want all the output matrices to have same dimensions. An example of input matrices (first column) would be:
t1(:,1)=[1; 2; 3; 5];
t2(:,1)=[2; 3; 4; 5];
t3(:,1)=[1; 2; 3; 4; 6];
t4(:,1)=[1; 3; 4; 6];
In this case, I want output matrices have the same first column [1:6]'. The missing rows will be filled with NaN.

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Andrei Bobrov
Andrei Bobrov 2011-9-30

0 个投票

variant 1
function zout = funforDZ(zin,r1)
%{
All matrixs (A,B,C ... and etc.) include in cell array 'zin'
zin = {A B C ...}
%}
c = zin(:);
M = cat(1,c{:});
if nargin < 2
r1 = (min(M(:,1)):max(M(:,1)))';
end
s = cellfun('size',c,1);
n = numel(s);
m = numel(r1);
z = nan(n*m,4);
X = mat2cell(bsxfun(@eq,r1,M(:,1)'),m,s);
[i1,j1] = find(blkdiag(X{:}));
z(:,1) = repmat(r1,n,1) ;
z(i1,2:end) = M(j1,2:end);
zout = mat2cell(z,repmat(m,n,1),4);
variant 2 with loop
function zout = funforDZloop(zin,r1)
%{
All matrixs (A,B,C ... and etc.) include in cell array 'zin'
zin = {A B C ...}
with loop
%}
if nargin < 2
c1 = cellfun(@(x)x(:,1),zin,'un',0);
M = cat(1,c1{:});
r1 = (min(M(:,1)):max(M(:,1)))';
end
n = numel(zin);
zout = cell(n,1);
z = nan(numel(r1),4);
for j1 = 1:n
zout{j1} = z ;
[i1,loc] = ismember(r1,zin{j1}(:,1));
zout{j1}(i1,:) = zin{j1}(loc(loc~=0),:);
end

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DZ
DZ 2011-9-30
Thank you Andrei for your scripts.
variant2 works if I provide r1. Otherwise the zout would be empty.
variant 1 did not work for me because I don't have bsxfun, and C compiler on my computer.
My matlab version is 7.0.1(R14)SP1. I wonder if that's a problem why some scripts you guys suggested don't work.

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更多回答（1 个）

Oleg Komarov
Oleg Komarov 2011-9-30

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function z = align4(reslst,varargin) % align matrices A, B, C and D
if isempty(reslst)
rlst = [min(cellfun(@(x) x(1,1),varargin)):max(cellfun(@(x) x(end,1),varargin))].';
else
rlst = reslst(:);
end
nList = numel(rlst);
nIn = numel(varargin);
z = cell(nIn,1);
for n = 1:nIn
z{n} = NaN(nList,size(varargin{n},2));
z{n}(ismember(rlst,varargin{n}(:,1)),:) = varargin{n};
end
An example:
t1 = [[2; 4; 6] randi(100,3,4)];
t2 = [[5; 7] randi(100,2,4)];
align4([],t1,t2)

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DZ
DZ 2011-9-30
Actually your script works as well.
The problem I had related to "cellfun" is that because my matlab version is old. I can get rlst in some other way without a problem. So, thanks for your input.

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