Replace NaN in table with a corresponding value in a different column

I have a table A with several columns (A1, A2, A3, A4... A33). I want to check Nan values in column A5, then replace them with the value in corresponding row in column A8.

Following is my code, but it does not seem to work correctly.

NewValue = A.A5;
  if isnan(A.A5)    
  NewValue = A.A8;
  end

I also tried to identified with (:,1) in the script. It does not seem to help.

NewValue(:,1)= A.A5(:,1);
  if isnan(A.A5(:,1))    
  NewValue(:,1) = A.A8(:,1);
  end

Answer 1

[Paolo]

You have not provided your table so I'll provide an example which should help you solve your problem. I have placed some NaNs in Age variable.

 LastName = {'Sanchez';'Johnson';'Li';'Diaz';'Brown'};
 Age = [38;NaN;NaN;40;NaN];
 Smoker = logical([1;0;1;0;1]);
 Height = [71;69;64;67;64];
 Weight = [176;163;131;133;119];
 BloodPressure = [124 93; 109 77; 125 83; 117 75; 122 80];
 T = table(LastName,Age,Smoker,Height,Weight,BloodPressure)

Table T:

     LastName     Age    Smoker    Height    Weight    BloodPressure
    _________    ___    ______    ______    ______    _____________

    'Sanchez'     38    true      71        176       124     93   
    'Johnson'    NaN    false     69        163       109     77   
    'Li'         NaN    true      64        131       125     83   
    'Diaz'        40    false     67        133       117     75   
    'Brown'      NaN    true      64        119       122     80

To replace the NaN values in the Age variable, with, let's say, the corresponding variables in Height, you can use logical indexing:

 T.Age(isnan(T.Age)) = T.Height(isnan(T.Age));

The resulting table:

     LastName     Age    Smoker    Height    Weight    BloodPressure
    _________    ___    ______    ______    ______    _____________

    'Sanchez'    38     true      71        176       124     93   
    'Johnson'    69     false     69        163       109     77   
    'Li'         64     true      64        131       125     83   
    'Diaz'       40     false     67        133       117     75   
    'Brown'      64     true      64        119       122     80

[Ivy Chen]

Thank! This works nicely!

[Ritesh]

@Paolo I have to put NaN in height column in same row as in age , then what will be the code for that

Answer 2

[dpb]

You need the logical addressing vector on both sides and address to return table to update the table...

idx=isnan(A.A5);
A(idx,'A5')=A(ix,'A8');

See the section on accessing data in a table for the many possible addressing modes available--it takes some time and experimentation to learn the "tricks" in getting the proper form for the desired task, granted. Access data in a table

[Ivy Chen]

Thanks for the tips!

[dpb]

The above works if the data are already in the table as opposed to creating the table afterwards -- that depends on which way one wants to go at it or, perhaps, if there are data added to an existing table.

I've never found the answer to the Q? as to whether the JIT optimizer is smart enough to recognize the replicated logical test as the other Answer also uses; hence I generally create the temporary to ensure that operation is only done once at the slight expense of a little more memory from the temporary that isn't released unless do so explicitly.