How to write the matrix with blank element?

    for i=1:10

if i~=6 T(i)=2*i

else T(i)= %(i want to leave it blank) end end

T

Is this possible in Matlab? If yes, How to do this?

[suvadip paul]

if T(6) cannot left blank, then I want to display T(6)= ND (Not defined) so that T= 2 4 6 8 10 ND 14 16 18 20

[Rohit Deshmukh]

is there any possibility of keeping the element blank?

I do not want nan or ND nor do i want to delete the element from matrix.

Answer 1

[Image Analyst]

Just set those elements to nan:

T(i) = nan;

otherwise you'd be looking at a cell array and that's a lot more complicated to use and you probably don't want the hassles of dealing with those. Nan means "Not a number" and is basically the concept of "not defined' that you're trying to achieve. They just call it nan instead of ND.

[Rawan Alghamdi]

I want something similar to this. I used to use NaN, but then when I want to mean a column with a NaN element it makes the whole col. = NaN.

E.g. NaN + any number = NaN

What can I use other than NAN?

[Image Analyst]

Use the 'omitnan' option for the mean() function.

columnMeans = mean(T, 1, 'omitnan');

[Rohit Deshmukh]

is there any possibility of keeping the element blank?

I do not want nan or ND nor do i want to delete the element from matrix.

[Image Analyst]

How do you have a "blank" in your matrix. Please supply a small example of such a matrix (actual code that will make it), and give your desired output.

[Ruben]

Hi,

Like Rohit, I would like to have blank elements in my vector (or maybe it's a "datetime array"?)

I'm plotting millions of lines of data in monthly chunks. For my plots I want xticks for every day but xtick labels only every other (second) day. In other words I want minor tickmarks every day, and major tickmarks every other day (I know there is the XMinorTick 'on' option, but I haven't figured that out yet so I'm also trying this strategy).

Below, I'm trying to include these blanks in my array, but instead of reading datetime([],[],[]) as a physical blank space, it just skips over it, leaving me with only the major tickmarks.

xlimit = [timestartm timeendm];
xtki = 2; % xtick interval is 2
xtkl = [(timestartm) (datetime([],[],[])) (timestartm + xtki) (datetime([],[],[])) (timestartm + 2*xtki)...
      (datetime([],[],[])) (timestartm + 3*xtki) (datetime([],[],[])) (timestartm + 4*xtki) (datetime([],[],[]))...
      (timestartm + 5*xtki) (datetime([],[],[])) (timestartm + 6*xtki) (datetime([],[],[]))...
      (timestartm + 7*xtki) (datetime([],[],[])) (timestartm + 8*xtki) (datetime([],[],[]))...
      (timestartm + 9*xtki) (datetime([],[],[])) (timestartm + 10*xtki)

[Image Analyst]

@Ruben start your own discussion thread and in there state what timestartm timeendm are.

[Steven Lord]

It is not possible to have an array in MATLAB (except for a Java array) that has "holes" in it.

For the question about tick labels on an axes where you've plotted a datetime array, that's not too difficult. Here's one with tick labels every day.

v = 0:10;
x = datetime('today') + days(v);
y = v.^2;
plot(x, y)
xticks(x)
title('Labels each day')

Here's one with a tick every day and a tick label every other day.

figure
plot(x, y)
xticks(x)
% Customize how the label strings are formatted 
x.Format = 'MMM dd';
s = string(x);
s(2:2:end) = "";
xticklabels(s)
title('Labels every other day')

[Ruben]

Thank you @Steven Lord, that solved my issue!

Answer 2

[Vidhya Dharshini]

Hi... try this

 for i=1:10
    if(i~=6)
        T=2*i
    else
        T='ND'
    end;
    T
end

just give T='ND' and it will display.

[Image Analyst]

But you're overwriting T every time, plus sometimes it's a double and other times it's a character string.

Answer 3

[Ruben]

Hi @Image Analyst,

Thanks for getting back to me!

Like @Rohit Deshmukh, I would like to have blank elements in my vector (or maybe it's a "datetime array"?)

I'm plotting millions of lines of data in monthly chunks. For my plots I want xticks for every day but xtick labels only every other (second) day. In other words I want minor tickmarks every day, and major tickmarks every other day (I know there is the XMinorTick 'on' option, but I haven't figured that out yet so I'm also trying this strategy).

Below, I'm trying to include these blanks in my array, but instead of reading datetime([],[],[]) as a physical blank space, it just skips over it, leaving me with only the major tickmarks.

% data is collected every minute
timestartm = datetime(2022,02,01);
timeendm = datetime(2022,02,28);
xlimit = [timestartm timeendm];
xtki = 2; % xtick interval is 2
xtkl = [(timestartm) (datetime([],[],[])) (timestartm + xtki) (datetime([],[],[])) (timestartm + 2*xtki)...
      (datetime([],[],[])) (timestartm + 3*xtki) (datetime([],[],[])) (timestartm + 4*xtki) (datetime([],[],[]))...
      (timestartm + 5*xtki) (datetime([],[],[])) (timestartm + 6*xtki) (datetime([],[],[]))...
      (timestartm + 7*xtki) (datetime([],[],[])) (timestartm + 8*xtki) (datetime([],[],[]))...
      (timestartm + 9*xtki) (datetime([],[],[])) (timestartm + 10*xtki) (datetime([],[],[]))...
      (timestartm + 11*xtki) (datetime([],[],[])) (timestartm + 12*xtki) (datetime([],[],[]))...
      (timestartm + 13*xtki) (datetime([],[],[])) (timestartm + 14*xtki) (datetime([],[],[]))]

Answer 4

[Image Analyst]

You're posting this as an "Answer" to a question that people can see (by the green box) that has already been successfully answered. So many people will not open this and look at your question. Again it's best if you start a new question - not anywhere here in this discussion thread, but a brand new question all your own. More people will see it and answer it then.

TUTORIAL: How to ask a question (on Answers) and get a fast answer

If you can mock up some desired output, whether it's some numbers or a picture of something you drew in Photoshop, such as a plot or whatever. But people need to see what you'd like to achieve as a solution.

[Ruben]

Oh I understand now. Thanks for explaining that to me and sending me the tutorial.