Sort rows of a table by column within a variable

I have a table:

T =
        a                       v               
    ________    _______________________________

     0.88517    0.33536     0.65376     0.89092
     0.91329    0.67973     0.49417     0.33416
     0.79618    0.13655     0.77905     0.69875
    0.098712    0.72123     0.71504     0.19781
     0.26187    0.10676     0.90372    0.030541

I want to sort the table using the last column of v. This is the closest I could find but obviously it does not work (thus I am posting the question):

     sortedT = sortrows(T,'v')

I am not sure how it sorts in this case:

sortedT =
       a                       v               
    ________    _______________________________

     0.26187    0.10676     0.90372    0.030541
     0.79618    0.13655     0.77905     0.69875
     0.88517    0.33536     0.65376     0.89092
     0.91329    0.67973     0.49417     0.33416
    0.098712    0.72123     0.71504     0.19781

I also looked up in sortrow documentation but could not find anything there (did I slip?).

Your help is highly appreciated! Thank you.

[BN]

I think it could be done if you convert your table to matrix then sort it as you like and the return it to table. Jus an idea...

[J AI]

Yes, I suppose I could do that. I have actually achieved what I was trying to achieve in a different way already. So, just as a learning process, let's see if there is a direct way we can achieve this.

Answer 1

[Harsha Priya Daggubati]

Hi,

As you can see from the data, whenever you apply sortrows to your table, by giving your column name as 'v' data will be sorted based on the first column of your merged column 'v'.

As a workaround, you can use 'splitvars' method to update your table and apply sortrows, then later merge your table which you need as a final result using 'mergevars'.

Here is the code to it:

a = [0.88517 ;0.91329;0.79618;0.098712;0.26187];
v = [ 0.33536     0.65376     0.89092; 0.67973     0.49417     0.33416; 0.13655     0.77905     0.69875; 0.72123     0.71504     0.19781; 0.10676     0.90372    0.030541];
tbl = table(a,v)
tbl1 = splitvars(tbl);
tbl1 = sortrows(tbl1,[4]);
finaltbl = mergevars(tbl1,[2 3 4],'NewVariableName','v');

Hope this helps!

Answer 2

[Eric Sofen]

There isn't a one-line solution to this, but here's another approach that hoists the data you want to sort by out of the table and then uses the sort index (second output of sortrows) to sort the table itself:

% Setup
t = readtable("patients.xls",TextType="string");
t.BloodPressure = [t.Systolic, t.Diastolic];
t = removevars(t,["Systolic","Diastolic"]);

% Sort the second column of the BloodPressure Variable to get the sort order
[~,i] = sortrows(t.BloodPressure(:,2));
% Index back into t with the sort order.
tsorted = t(i,:)

tsorted = 100×9 table
     LastName      Gender     Age             Location              Height    Weight    Smoker    SelfAssessedHealthStatus    BloodPressure
    __________    ________    ___    ___________________________    ______    ______    ______    ________________________    _____________

    "Thomas"      "Female"    42     "St. Mary's Medical Center"      66       137      false           "Poor"                 115     68  
    "Davis"       "Female"    46     "St. Mary's Medical Center"      68       142      false           "Good"                 121     70  
    "Cooper"      "Female"    28     "VA Hospital"                    65       127      false           "Good"                 115     73  
    "Bryant"      "Female"    48     "County General Hospital"        66       134      false           "Excellent"            129     73  
    "Jackson"     "Male"      25     "VA Hospital"                    71       174      false           "Poor"                 127     74  
    "Carter"      "Female"    38     "St. Mary's Medical Center"      63       128      false           "Good"                 120     74  
    "Morgan"      "Female"    41     "St. Mary's Medical Center"      66       134      false           "Good"                 120     74  
    "Brooks"      "Male"      39     "St. Mary's Medical Center"      72       176      false           "Excellent"            120     74  
    "Griffin"     "Male"      49     "County General Hospital"        70       186      false           "Fair"                 119     74  
    "Jones"       "Female"    40     "VA Hospital"                    67       133      false           "Fair"                 117     75  
    "Clark"       "Female"    48     "VA Hospital"                    65       133      false           "Excellent"            121     75  
    "James"       "Male"      25     "County General Hospital"        66       186      false           "Good"                 125     75  
    "Bennett"     "Female"    35     "County General Hospital"        64       131      false           "Fair"                 121     75  
    "Robinson"    "Male"      50     "County General Hospital"        68       172      false           "Good"                 125     76  
    "Young"       "Female"    25     "County General Hospital"        63       114      false           "Good"                 125     76  
    "Evans"       "Female"    39     "County General Hospital"        62       121      false           "Good"                 123     76