Calculate Standard deviation in table

Hi,

I have a table with 20 columns, I want to make a new column with the standard deviation of each row from column 4 to 6.

So after column 6 i want to have a column with the stdev of all rows of column 4:6.

How can I do that?

Answer 1

[Chunru]

a = array2table(rand(5,8))      % Sample table

a = 5×8 table
     Var1       Var2       Var3        Var4        Var5        Var6        Var7       Var8  
    _______    _______    _______    _________    _______    _________    _______    _______

     0.4022     0.9627    0.53548      0.35205    0.70636      0.89738    0.50393    0.44203
    0.96785    0.33289    0.57833      0.36493    0.84985    0.0031283    0.34461     0.3312
    0.29543    0.18861    0.91065     0.025623    0.40162      0.88419    0.24007    0.38235
    0.66403    0.19131    0.24685    0.0092594    0.10672      0.51052    0.79236    0.43115
    0.62483    0.95579    0.37075      0.11087    0.65024      0.55079    0.97985    0.57458

s = std(a{:, 4:6}, [], 2)   % std along rows (dim=2)

s = 5×1

0.2767 0.4249 0.4304 0.2658 0.2870

b = [a table(s, 'VariableNames', {'std'})]   % combine with original

b = 5×9 table
     Var1       Var2       Var3        Var4        Var5        Var6        Var7       Var8        std  
    _______    _______    _______    _________    _______    _________    _______    _______    _______

     0.4022     0.9627    0.53548      0.35205    0.70636      0.89738    0.50393    0.44203    0.27671
    0.96785    0.33289    0.57833      0.36493    0.84985    0.0031283    0.34461     0.3312    0.42485
    0.29543    0.18861    0.91065     0.025623    0.40162      0.88419    0.24007    0.38235    0.43038
    0.66403    0.19131    0.24685    0.0092594    0.10672      0.51052    0.79236    0.43115    0.26577
    0.62483    0.95579    0.37075      0.11087    0.65024      0.55079    0.97985    0.57458    0.28704

[Dion Theunissen]

Thanks!

Answer 2

[Erkan MSN]

If you want to calculate the standard deviation of the whole table:

For example "cax" is table.

    1.6424    5.2601    1.4691    0.7361    0.2771
    1.0531    0.5722    1.8804    4.9636    0.9451
    1.8084    1.6537    1.5916    0.8352    0.7740
    0.7550    1.4221    1.7003    2.5646    0.4272
    2.2935    2.5158    0.7656    1.0110    2.0810
    1.0765    0.5390    1.9687    2.0829    0.4572
    1.0493    1.4736    1.2810    1.0911    0.2073
    2.1630    0.5679    2.8582    1.6006    0.4746
    1.1625    0.7333    0.2623    0.6887    0.7897
    2.9148    0.2886    3.1662    0.3645    0.5730
    
    std(cax,[],'all')
    ans =

   1.0786e+03