Deleting several specific columns from a table

I would like to delete several hundred columns from a table of data. I'm currently using the commands:

QuestionnairesData(:,4:5) = []

QuestionnairesData(:,5:6) = []

QuestionnairesData(:,6:7) = []

But this goes on for several hundred lines which would take hours to run. Does anyone know a more efficient way to do this? Thank you!

Answer 1

[the cyclist]

Do you know all the column indices you want to delete? It's as simple as

columnIndicesToDelete = [4 5 6 7 9 12 14 15 17]; % and so on
QuestionnairesData(:,columnIndicesToDelete) = [];

And if there is some pattern to the indices, you won't necessarily have to specify every single value.

Or am I missing something? In your example, the columns deleted in the command

QuestionnairesData(:,5:6) = [];

after having done

QuestionnairesData(:,4:5) = [];

will not be the 5th and 6th column of the original array. So maybe there is some complication there?

[Darla Bonagura]

I just tested out the first command you provided and it worked beautifully. Thank you! Do you think if I enter 300+ values into the brackets that it could cause MATLAB to crash?

The reason I set it up as described is because after I deleted columns 5 and 6 (100x10), 4 and 5 become the next columns I want to delete (100x8). As a MATLAB beginner, I'm learning that wasn't the most efficient way to do it.

Thank you again!

[Jos (10584)]

No it will not crash!

T = array2table(randi(100,2,100000)) ; % a table with 100000 columns!
idx = 2:99999 ;
T(:,idx) = [] % delete 99998 columns

[Alexander Carmeli]

This line will conveniently remove every column that has all-zero elements:

t(:,~any(t{:,:})) = []