Home > helper > tips_n_tricks.m

tips_n_tricks

PURPOSE ^

**************************************************************************

SYNOPSIS ^

This is a script file.

DESCRIPTION ^

**************************************************************************
*                                                                        * 
*                       MATLAB TIPS AND TRICKS                           * 
*                                                                        *
**************************************************************************

CROSS-REFERENCE INFORMATION ^

This function calls: This function is called by:

SOURCE CODE ^

0001 %**************************************************************************
0002 %*                                                                        *
0003 %*                       MATLAB TIPS AND TRICKS                           *
0004 %*                                                                        *
0005 %**************************************************************************
0006 
0007 %% Creating constant array
0008 siz = [1000 1000 3];
0009 val = 49;
0010 x = repmat(val, siz);
0011 % Avoid using
0012 % x = val * ones(siz); % for it does unnessary multipications
0013 
0014 %% Creating uniformly spaced elements
0015 lower = 1;
0016 upper = 100;
0017 n = 64;
0018 x = linspace(lower,upper,n);        % row vector
0019 x = linspace(lower,upper,n).';      % col vector
0020 
0021 %% SHIFTING
0022 x = linspace(1,10,10);
0023 
0024 shiftRt  = x( [ end  1:end-1 ] );          % shift right/down 1 element
0025 shiftRtX = x( [ end-k+1:end  1:end-k ] );  % shift right/down k elements
0026 
0027 shiftLt  = x( [ 2:end  1 ] );              % shift left/up 1 element
0028 shiftLtX = x( [ k+1:end  1:k ] );          % shift left/up k elements
0029 
0030 dim = 2;
0031 idx = repmat( {':'}, ndims(x), 1);         % initialize subscripts
0032 n   = size(x, dim);                        % length along dimension dim
0033 k = 3;
0034 
0035 idx{dim} = [ n  1:n-1];                    % shift right/down/forward 1 element
0036 idx{dim} = [ n-k+1:n   1:n-k];             % shift right/down/forward k elements
0037 idx{dim} = [ 2:n   1];                     % shift left/up/backward 1 element
0038 idx{dim} = [ k+1:n   1:k];                 % shift left/up/backward k elements
0039 
0040 newX = x(idx{:});
0041 
0042 %% REPLICATING
0043 
0044 %% Constant number of time
0045 a = [4 5];
0046 n = 5;
0047 b = a(ones(1,n),:);
0048 b = b(:).';
0049 
0050 b = repmat(a, [n n]);
0051 
0052 %% RESHAPING
0053 im = imread('impression.jpg');
0054 imx = ones(size(im,1),size(im,2),size(im,3),10);
0055 imx(:,:,:,1) = im;
0056 for it = 2: 10;
0057     imx(:,:,:,it) = imx(:,:,:,it-1)+15;
0058 end
0059 whos imx
0060 
0061 ims = repmat(im, [1 1 10]);
0062 ims = reshape(ims, [size(ims,1), size(ims,2), 3, size(ims,3)/3]);
0063 whos ims
0064 
0065 % Convert to 4-D grid
0066 % squeeze(); % remove singleton dimension
0067 % permute(); % switch the dimentions of multi-dimension image
0068 
0069 %% ROTATING
0070 
0071 %% BASIC ARITHMETIC OPERATIONS
0072 
0073 
0074 
0075 
0076 
0077 
0078

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