how can i know if x position of a vector is empty?

im trying this to know if that element(1,2) is empty or zero, to make a decision from that condition

if (ps1(1,2))==0
    paredes1=1;
else
    paredes1=length(ps1);
end

i was watching function like isempty or ismissing but its doesnt works.

[per isakson]

IMO, never use the function length(M) when M is an array. With vectors its ok. Use size(M,1) and size(M,2), respectively.

Answer 1

[Image Analyst]

Element (1,2) of a numerical array will never be empty. It can't be. A whole array can be empty, or you can set a whole column or row of a matrix to null ([]) which will delete the column or row, but then it will be gone and the array will be smaller. It will not be empty.

To determine if that element is 0 you can simply do

if ps(1,2) == 0
    % That element is 0.
end

Answer 2

[Karan Kannoujiya]

Hi Erick,

So you want to check whether a element is ps1(in your case) is 0 or not.

So, isempty or ismissing function will not work here. Because 0 is itself a element. If in a vector there is 0 it doesn't mean it is empty or missing. For checking a vector element for 0 then you must check by indexing as you have done.

therefore, isempty function is used to check if a memory location is allocated whether there is an element present or not.

for e.g lets take a string str=["abc" "xyz" ""]

So, in str at pos 3 we have allocated memory but there is no element present there

[Erick Guzman]

Hi karan bro, im so sorry i mean:

im trying this to know if that element(1,2) is empty , to make a decision from that condition.

[per isakson]

If element is a string array

str = ["abc","xyz",""];
find( strlength( str ) == 0 )

ans = 3

strlength( str(1,3) ) == 0

ans = logical
   1

[Erick Guzman]

okok actually, are points (x,y), where the vector is filled, but i need to know if there is only a point or more, then im trying by this way because if i do l=length(ps1), with only a point this length give me equal 2.

i let you some caps for you understanding.

thank u.

best regards.

[Image Analyst]

A 1x2 vector (x,y) will have a length of 2 since the length is the length of the longest dimension. You should use size():

[rows, columns] = size(ps1)

By the way did you see my explanation below?

[Erick Guzman]

this works perfectly, thanks a lot.