In terms of its performance, it takes ~7 seconds to convert and save a matrix with 100 million elements to a CSV file. Wide_to_long(wide_matrix, true, "~/test.csv", single(x) I have come up with the following function: function dt_long = wide_to_long(varargin)ĭefaults = ĭefaults(1:(nargin-1)) = varargin(2:end) ĭt_long = precision_fun(, 1)]) Īn example use case would be wide_matrix = rand(4,3,2) Here the first two dimensions mark the position of the values in the wide_array, whereas the third dimension contains the values that were stored in the original array. If you want to show a number that has a very long decimal part on a long basis, you could type format long to show it in the first 16 characters at Command Window at Matlab as above. If we have the wide_array =, then the long format of this array would be long_array = Is there a way to convert a matrix to a matrix in a long format in MATLAB in a fast way? Saving a ~7GB matrix takes at least 40mins. However, using loops in MATLAB is too slow. Writematrix(dt_long, save_path, 'Delimiter',',') Parfor (i_comd = 1:size(all_combinations, 2), 3)ĭt_long(i_comd, :) = Use the format function to control the output format of the numeric values displayed in the Command Window. for " + save_pathĭt_long = precision_fun(zeros(prod((size(wide_array)), 'all' ), n_dims+1)) Īll_combinations = combvec(1:n_rows, 1:n_cols) MATLAB performs all computations in double precision. function wide_to_long(wide_array, save, save_path, precision_fun) In R, this can be done with functions such as reshape2, or melt, but in MATLAB the only way I could find was to use for loops to create a new matrix.
#MATLAB FORMAT LONG EXAMPLE HOW TO#
The symbols +, -, and blank display for positive, negative, and zero elements.Ī final format command, format compact, suppresses many line-feeds that appear between matrix displays and allows more information to show on the screen.In MATLAB, how to convert a matrix to a long format? The + format is a compact way to display large matrices. With the short and long formats, if the largest element of a matrix is larger than 1000 or smaller than 0.001, a common scale factor is applied to the entire matrix when it is displayed. format short: 5 digit scaled fixed point: 3.1416: format long: 15 digit scaled fixed point: 3.
The other formats show more significant digits or use scientific notations. The default format, called the short format, shows approximately five significant decimal digits. If at least one element of a matrix is not an exact integer, several output formats are possible. matrix is the Hilbert matrix: In Matlab, the NxV Hilbert matrix is obtained simply by >A-hilb(N For N-3, do the following in matlab (format long) 1. If all the elements of a matrix are exact integers, the matrix displays in a format without any decimal points. The format command affects only how numbers are displayed, not how they are computed or saved. You can use the format command control the numeric display format.
Matlab displays the results of any assignments statement on the screen, and assigns it to the specified variable, or to ans if no variable is given.
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