Accessing variable in a table, depending on another variable

The output of the code is a table, containing the number and position of nodes in a maze.

Name = [];

Position = [];

number = 0;

Letter = 'N';

for j = 1 : size(is_node,2)

for i = 1 : size(is_node,1)

if is_node(i,j) == 1

number = number + 1;

Order = string(number);

name = Letter + Order;

Name = [Name;name];

position_y = i;

position_x = j;

Position = [Position;position_y,position_x];

end

end

end

node_table = table(Name,Position);

end

Output:

Name Position

_____ ________

"N1" 2 2

"N2" 4 2

"N3" 6 2

"N4" 10 2

"N5" 4 4

"N6" 6 4

"N7" 8 4

"N8" 10 4

"N9" 6 6

"N10" 8 6

"N11" 10 6

"N12" 2 8

"N13" 4 8

"N14" 6 8

"N15" 8 8

"N16" 10 8

"N17" 4 10

"N18" 6 10

"N19" 10 10

"N20" 2 12

"N21" 4 12

"N22" 6 12

"N23" 8 12

"N24" 10 12

I need to write a code that finds the number of a node without "N", depending on its position. For example: 10 6 should result in 11.

Any hint will help.

Thanks in advance.

[dpb]

What have you tried and where did you have a specific problem?

You might find the new(ish) pattern family of functions of interest...

Answer 1

[Voss]

% Create a table:
is_node = false(12);
is_node(2,2) = true;
is_node(4,2) = true;
is_node(6,2) = true;
is_node(10,2) = true;
is_node(4,4) = true;
is_node(6,4) = true;
is_node(8,4) = true;
is_node(10,4) = true;
is_node(6,6) = true;
is_node(8,6) = true;
is_node(10,6) = true;

Name = [];
Position = [];
number = 0;
Letter = 'N';
for j = 1 : size(is_node,2)
    for i = 1 : size(is_node,1)
        if is_node(i,j) == 1
            number = number + 1;
            Order = string(number);
            name = Letter + Order;
            Name = [Name;name];
            position_y = i;
            position_x = j;
            Position = [Position;position_y,position_x];
        end
    end
end
node_table = table(Name,Position)

node_table = 11×2 table
    Name     Position
    _____    ________

    "N1"      2     2
    "N2"      4     2
    "N3"      6     2
    "N4"     10     2
    "N5"      4     4
    "N6"      6     4
    "N7"      8     4
    "N8"     10     4
    "N9"      6     6
    "N10"     8     6
    "N11"    10     6

% find the Name(s) where Position is position:
position = [10 6];

% one way:
idx = node_table.Position(:,1) == position(1) ...
    & node_table.Position(:,2) == position(2);

node_number = node_table.Name(idx)

node_number = "N11"

% another way:
idx = ismember(node_table.Position,position,'rows');

node_number = node_table.Name(idx)

node_number = "N11"

[Voss]

node_number = "N11"

node_number = "N11"

node_number = extractAfter(node_number,1)

node_number = "11"

And, if you want it to be numeric:

node_number = str2num(node_number)

node_number = 11

By the way, I restored your question so that others who have a similar question in the future may benefit.