How to compare two input arguments of type table

I am trying to import my data from .csv file. This data includes characters and dates(with time). I imported this data as a table and now try to perform simple operations such as comparing the character field with a value or compare two date field. I used the following:

formatSpec = '%f%C%C%C%{MM/dd/yyyy HH:mm}D%{MM/dd/yyyy HH:mm}D';

T = readtable('Flights.csv','Delimiter',',', ... 'Format',formatSpec);

T

and the output looks like this:

T =

       FLIGHTID        ACID      DEPTAIRPORT    ARRAIRPORT        DEPTDATE            ARRDATE     
    ______________    _______    ___________    __________    ________________    ________________

    20160100000000    DAL1448    ATL            DTW           01/06/0016 12:10    01/06/0016 17:10

Now I need to check to see if DEPTDATE is earlier than ARRDATE or later. I used the following syntax and got an error:

if T(1,5) > T(1,6) 1 else 2 end

error: Undefined operator '>' for input arguments of type 'table'.

Error in input (line 12) if T(1,5) > T(1,6)

Also, how can I check to see if T(1,2) = 'DAL1448' and if yes, then print "match found"?

Thanks for your help.

Answer 1

[michio]

If you want to compare two single values of the same type in the table variable, use {} instead of (),

T{1,5} > T{1,6}

Also

idx = T{:,5} > T{:,6};
T(ind,:)

could find the rows that match the condition (DEPTDATE is earlier than ARRDATE or later). To find rows with ACID being 'DAL1448',

T(T.ACID == 'DAL1448',:)

may do the job.

varfun is also a convenient function that applies function to table variables.

[Ehsan Es]

Michio, Thanks for your help. It did it.

[Peter Perkins]

More readable, but equivalent, syntaxes might be

T.DEPTDATE(1) > T.ARRDATE(1)

or

T{1,'DEPTDATE'} > T{1,'ARRDATE'}

Hope this helps.

[ADC]

I've got the same problem, I've imported data from a datasheet and I need to filter only the row that contain an assigned value, but it does'nt work!!!

the error I get is:

Undefined operator '==' for input arguments of type 'cell'.

I tryed to use this exspression:

A(A.NAerogenerador == '109',:)

or this

W=A(A(:,2)==109,:);

but still does'nt work

[Peter Perkins]

Presumably A.NAerogenerador is a cell array of text, in which case you need strcmp. Switch to using string arrays, and you can use ==.

A(:,2)==109 won't work for two reasons:

1) A(:,2) is a (one-variable) table, which == won't work on

2) A{:,2}==109 would be the second variable (probably equivalent to A(:,2)==109, but hwo knows with no example), and == doesn't work on cell arrays, and in any case 109 is numeric.

Answer 2

[Lucie Sanchez]

Hi,

I've got the same issue, before upload Matlab it worked but now it crases. It's not my code and I don't understand a lot so I don't really know where is the problem.

for n=1:size(correct,1)
   if correct(n,1)>0 || correct(n,2)>0
       peaks=polyval(parms(n,:),ex)
   end
end

But I receive an error message:

"Undefined operator '>' for input arguments of type 'table'.

if correct(n,1) > 0 || correct(n,2) > 0 %test for no-filter condition"

I tried to change parentheses by curly braces after some research but unsuccessfully...it leads to other errors...

[Peter Perkins]

Lucie, you should start a new thread.

It appears that "correct" used to be a numeric matrix, and now it's a table. That's happening upstream of the code you are looking at, you you need to provide more context.

In a new thread.