How do I range through a set of columns in a table to generate data and store data in new columns?

Hi,

I've got a 33x12 table "T", where I'd like to generate 8 new columns of data ("Result 1 - 8") by doing a simple calculation of going through values in Column 1-8 one at a time and multiplying each of them with data in Column 12 ("FixedConcentration") and muliplying that by 100. I can do this calculation for one column at a time by doing this...

T.Result1 = (T.APConcentration_mM__1)./(T.FixedConcentration).*100 

...but would like this to be done automatically. I use readtable to get the excel file into MATLAB but I'm stuck on how to create a loop that accesses the data column 1-8. Apologies if this is a simple question, but I have limited programming experience and I'd appreciate any help.

Thank you.

Answer 1

[Star Strider]

Try this:

T1 = readtable('matlab table.xlsx', 'VariableNamingRule','preserve');

Result = array2table(T1{:,1:8}.*T1.FixedConcentration*100, 'VariableNames',compose('Result%d',1:8));
T1 = [T1,Result];

The first five rows of the new table are then:

      Value1        Value2        Value3        Value4        Value5        Value6        Value7        Value8       ID 1      ID 2            Quantity           FixedConcentration    Result1    Result2    Result3     Result4     Result5    Result6    Result7     Result8 
    __________    __________    __________    __________    __________    __________    __________    __________    ______    ______    ______________________    __________________    _______    _______    _______    _________    _______    _______    ________    ________

    -0.0034822    -0.0087225    -0.0096823     -0.010581    -0.0075441    -0.0063167    -0.0050771    -0.0033302    {'A1'}    {'1' }    {'2.896930253098927' }          1.8244          -0.6353    -1.5914    -1.7665      -1.9304    -1.3764    -1.1524    -0.92628    -0.60758
       0.05166      0.062327      0.053914      0.059795      0.073784      0.050638      0.052084      0.041851    {'A2'}    {'9' }    {'1.8881568931671828'}          4.2058           21.727     26.214     22.675       25.149     31.032     21.297      21.906      17.602
     -0.011543    -0.0090813    -0.0099802     -0.010053      -0.01124     -0.010381    -0.0097284    -0.0092605    {'A3'}    {'17'}    {'2.8327923105329047'}          3.7978          -4.3837    -3.4489    -3.7903      -3.8178    -4.2688    -3.9424     -3.6947      -3.517
      0.016241      0.016529      0.023821    -0.0031858      0.026756      0.046819      0.028462      0.057366    {'A4'}    {'25'}    {'1.823551230561143' }         0.28849          0.46853    0.47685    0.68719    -0.091905    0.77189     1.3507     0.82109      1.6549
      0.021792      0.026289      0.041477      0.037204      0.020308      0.021495      0.030704        0.0308    {'A5'}    {'33'}    {'2.108249264604965' }          4.9974            10.89     13.138     20.728       18.592     10.149     10.742      15.344      15.392

Note that your question text mentioned ‘multiply’, however the example as a division, so this may be what you actually want:

      Result = array2table(T1{:,1:8}./T1.FixedConcentration*100, 'VariableNames',compose('Result%d',1:8));

The rest of the code is unchanged.

[schilakwad]

That works, thank you!

[Star Strider]

As always, my pleasure!

Answer 2

[Seth Furman]

You might be interested in varfun.

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

[schilakwad]

Thank you!