An efficient way to round decimal numbers up to the n-decimal in a cell array

eIs there an efficient way to round decimal numbers up to the n-decimal in a cell array?

In the following example, I would like to round the decimal numbers up to n=2, i.e. to the second decimal:

a = [
    {[ 0.235089379668094 0]}
    {[0.0793405810870535 0]}
    {[ 0.142843392632868 0]}
    {[ 0.639081029130393 0]}
    {[ 0.970756532033504 0]}
    {[                 1 0]}]

My desired output would be the following one:

a = [
    {[0.24 0]}
    {[0.08 0]}
    {[0.14 0]}
    {[0.64 0]}
    {[0.97 0]}
    {[  1 0]}]

Answer 1

[Jatin Singh]

Hi @Sim,

Yes, this can be efficiently done using the "cellfun" function in MATLAB.

"cellfun" applies a particular function to the contents of each cell of the cell array, In this case we can write a function to round decimal to two places and apply it to the cell array using this function.

Kindly refer the below example which rounds the contents of cell array to nth decimal places.

% Example cell array with decimal numbers
C = {1.234, 2.345, 3.456; 4.567, 5.678, 6.789};

% Number of decimal places to round up to
n = 2;

% Function to round up to the n-th decimal place
roundUpToNDecimals = @(x) ceil(x * 10^n) / 10^n;

% Apply the function to each element in the cell array
C = cellfun(roundUpToNDecimals, C);

disp(C);

If you would have a numeric array instead of a cell array this can be done efficiently using the element-wise operation like in the following example:

% Example numeric matrix with decimal numbers
M = [1.234, 2.345, 3.456; 4.567, 5.678, 6.789];

% Round up to the second decimal place
M = round(M,2);

disp(M);

You can refer the documentation of "cellfun" for more details:

https://www.mathworks.com/help/matlab/ref/cellfun.html

Hope this helps

[Sim]

Thanks @Jatin Singh, very kind, it is the same I wrote :-)

[Jatin Singh]

Yes, you figured it out pretty well.

Answer 2

[Sim]

maybe I found it... (?)

a = [
    {[ 0.235089379668094 0]}
    {[0.0793405810870535 0]}
    {[ 0.142843392632868 0]}
    {[ 0.639081029130393 0]}
    {[ 0.970756532033504 0]}
    {[                 1 0]}];
cellfun(@(x)round(x,2),a,'UniformOutput',false)

[Stephen23]

A more efficient way would be to store your data in a numeric matrix.

[Sim]

How to do it ? :-) If you want to write it down in an answer I will accept it :-)

[Stephen23]

"How to do it"

m = [0.235089379668094,0; 0.0793405810870535,0; 0.142843392632868,0; 0.639081029130393,0; 0.970756532033504,0;1,0]

m = 6x2

0.2351 0 0.0793 0 0.1428 0 0.6391 0 0.9708 0 1.0000 0

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m = round(m,2)

m = 6x2

0.2400 0 0.0800 0 0.1400 0 0.6400 0 0.9700 0 1.0000 0

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[Sim]

Ahhh, in that way..! I did not understand before, it is now clear! Thanks a lot :-)