How to round numbers in tables?

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Hao Tang 2018-2-22

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https://ww2.mathworks.cn/matlabcentral/answers/384311-how-to-round-numbers-in-tables

评论： the cyclist 2021-10-2

How can I round a number in a matlab table after it does its calculation? I have a cell that calculates the value to be 0.009999998 but I want it to read 0.01. I tried using format short g in the script but that didn't work.

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Answer 1

the cyclist 2018-2-22

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编辑：the cyclist 2018-2-22

在 MATLAB Online 中打开

Use the round function.

You could have discovered this for yourself by typing

docsearch round

in the MATLAB command window, or typing

round matlab

into Google.

Note that there is a difference between the value that is calculated/stored, and how it is displayed. The format command is about the display.

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Bill Tubbs 2021-10-2

在 MATLAB Online 中打开

I found the round function doesn't work with tables:

>> round(table(randn(3,4)), 3)
Error using round
First argument must be a numeric, logical, or char array.

So this answer was not helpful.

the cyclist 2021-10-2

See my comment on your "answer" below.

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Answer 2

Star Strider 2018-2-22

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If you do not have the R2015a (I believe that is the correct release) that introduced the new round function, this anonymous function emulates it:

roundn = @(x,n) round(x .* 10.^n)./10.^n;   % Round ‘x’ To ‘n’ Digits, Emulates Latest ‘round’ Function
x = 0.009999998;
xr = roundn(x,2)
xr =
         0.01

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Star Strider 2018-2-23

@Guillaume — Thank you!

Lance Yarbrough 2019-4-14

编辑：Lance Yarbrough 2019-4-14

THANK YOU!! Looking for this answer forr most of the DAY.

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Answer 3

Bill Tubbs 2021-10-2

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Is here a way to use the round function with tables?

Simply using round(my_table, 3) does not work:

t = array2table(randn(3, 4), 'VariableNames', {'A', 'B', 'C', 'D'}, ...
    'RowNames', {'1', '2', '3'});
round(t, 3)

Output:

Error using round

First argument must be a numeric, logical, or char array.

I found this solution but it's quite convoluted:

t2 = t; t2{:, :} = round(t.Variables, 3)

Output:

t2 =

3×4 table

A B C D

______ ______ ______ ______

1 0.722 0.187 -0.439 -0.888

2 2.585 -0.082 -1.795 0.1

3 -0.667 -1.933 0.84 -0.545

Surely there is a better way...

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Bill Tubbs 2021-10-2

Thanks but this doesn't preserve the row and column names, and possibly other attributes of the table.

I found the same question answered here by Steven Lord STAFF MVP.

the cyclist 2021-10-2

OK. I can't tell from this comment whether you ended up with a solution that works for you.

If not, you might want to start a new question with your specific needs, rather than commenting and "answering" on an older question. You'll typically get more eyes on it if you do.

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