Hi Luca, A Monday 07 January 2008, Ivan Vilata i Balaguer escrigué: > Luca Della Santina (el 2008-01-07 a les 11:16:25 +0100) va dir:: > >[...] > > I would like to modify the value contained in the third column of > > the second row from the original value of 4 to 5 but couldn't find > > a quick way to do it inside the pytables manual. > > > > In first stance i tried to: > > mytable[1][2] = 5 > > mytable.flush() > > > > but in this way the new value is not written into the table (even > > if no errors were reported).
This is because you should understand what's going on under the hood. When you call mytable[1], this returns a row of the table as a NumPy scalar (of 'void' type), and hence mytable[1][2] will set the 3rd field of such (temporal) scalar. So, the result is that your code won't do nothing. > ``Table.modifyColumn()`` is your friend:: > > mytable.modifyColumn(start=1, colname='name_of_field2', > column=[5]) mytable.flush() You can use also the .cols accessor, which is slightly more confortable IMO: mytable.cols.name_of_field2[1] = 5 or, if you prefer using the field index instead of the name: mytable.cols._f_col(mytable.colnames[2])[1] = 5 BTW, a Table.flush() is only needed when you append/modify the Table using an iterator, so you don't need to issue it in this case. Ciao, -- >0,0< Francesc Altet http://www.carabos.com/ V V Cárabos Coop. V. Enjoy Data "-" ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Pytables-users mailing list Pytables-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/pytables-users
