How do I return the indexed values unsorted, in the original order in which they appear in a vector?

What I'm trying to accomplish seems like it should be much easier, however I acknowledge that I am not proficient at all and am probably misunderstanding the utlity of this indexing.

There's a couple things I am trying to see if I can resolve:

1) radius_gl ( as shown below is 18 x3) which is not allowing the return of indexed values beyond the limit of 18 even though gamt/lamt have repeat values.

a) Is there a way around this?

2) r1 and r2 was previously returning only 12 or 11 indexed values; this was not the right because 20 values should have been returned, and they were in a sorted order

This is the current code:

75	15	25 % col_1 = G; col_2 = L; col_3 = radii; 
77	17	25
79	19	50
81	21	50
83	23	75
85	25	75
87	27	100
89	29	100
91	31	125
93	33	125
95	35	150
97	37	150
99	39	175
101	41	175
103	43	200
105	45	200
107	47	225
109	49	225

% heres a snippet of the lamt (20 x 1); gamt is structured the same but has
% different range of numbers
47
43
21
43
17
17
47
45
43
19
33
29

idx_gamt = find(ismember(gamt, radius_gl(:, 1),"rows"));
idx_lamt = find(ismember(lamt, radius_gl(:, 2), "rows"));

r1 = radius_gl(idx_gamt, 3);
r2 = radius_gl(idx_lamt, 3);

Answer 1

[Voss]

radius_gl = [75	15	25 % col_1 = G; col_2 = L; col_3 = radii; 
77	17	25
79	19	50
81	21	50
83	23	75
85	25	75
87	27	100
89	29	100
91	31	125
93	33	125
95	35	150
97	37	150
99	39	175
101	41	175
103	43	200
105	45	200
107	47	225
109	49	225];

lamt = [47
43
21
43
17
17
47
45
43
19
33
29];

[ism_lamt,idx_lamt] = ismember(lamt,radius_gl(:,2));
r2 = radius_gl(idx_lamt(ism_lamt),3)

r2 = 12×1

225 200 50 200 25 25 225 200 200 50

Or, if you know all elements of lamt are in radius_gl(:,2), you can do away with ism_lamt:

[~,idx_lamt] = ismember(lamt,radius_gl(:,2));
r2 = radius_gl(idx_lamt,3)

r2 = 12×1

225 200 50 200 25 25 225 200 200 50

[Jade T]

Yes, I know all of the elements of lamt are in radius_gl. I wanted to be able to store them in the order they appear. Thank you very much!

[Voss]

You're welcome!

Answer 2

[Sulaymon Eshkabilov]

Understood your question correctly, this is what you are trying to achieve:

radius_gl = readmatrix('D_GAMT.txt');  % Copied your sample data
lamt = readmatrix('D_LAMT.txt');       % Copied your sample data   
gamt = lamt+randi(2, numel(lamt), 1);  % Sample data created
idx_gamt = find(ismember(radius_gl(:, 1), gamt, "rows"));
idx_lamt = find(ismember(radius_gl(:, 2), lamt,  "rows"));
r1 = radius_gl(idx_gamt, 3)

r1 =

  0×1 empty double column vector

r2 = radius_gl(idx_lamt, 3)

r2 = 8×1

25 50 50 100 125 200 200 225

[Jade T]

This is also what I got, but if you see in lamt, the first number in the column vector is 47 so r2 should shart with 225 and so on; in short, I want them ordered as they are in lamt, not numerically ordered consecutively. Does that make sense?