How to round numbers in tables?

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.

Answer 1

[the cyclist]

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.

[Bill Tubbs]

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]

See my comment on your "answer" below.

Answer 2

[Star Strider]

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

[Hao Tang]

How can I do this for table inputs? When I try to round(Table, 4) it doesn't work

[Guillaume]

How can I do this for table inputs? When I try to round(Table, 4) it doesn't work

neither does sin(Table) or Table + 5. You use round with tables the same way you use any other function with tables: by applying the function to table variables

yourtable.somevariable = round(yourtable.somevariable, 4);

If you want to apply it to all the table variables, then

yourtable = varfun(@(var) round(var, 4), yourtable)

[Star Strider]

@Guillaume — Thank you!

[Lance Yarbrough]

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

Answer 3

[Bill Tubbs]

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...

[the cyclist]

tbl = table(randn(3,4))

tbl = 3×1 table
                          Var1                      
    ________________________________________________

      0.77448     -0.91436         1.26      -2.1603
    -0.098984       0.7149     -0.42872      -2.0906
      0.84741      0.87568     -0.57396      0.39484

varfun(@(x)round(x,3),tbl)

ans = 3×1 table
                  Fun_Var1              
    ____________________________________

     0.774    -0.914      1.26     -2.16
    -0.099     0.715    -0.429    -2.091
     0.847     0.876    -0.574     0.395

[Bill Tubbs]

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]

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.