creating new variable using for loop and if-else condition

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Arturo Jr. Ongkeko on 12 Dec 2020
Hi,
I wish to divide my age data in column vector into age-groups 10-29, 20-29, 30-39, 40-49, 50-59, etc. using for loop and the if-else statements. here what I have started. but i wonder how to create that new variable age group.
for n=1:length(age)
if age(n)==10 & age(n)<=29
new_age_group1 = age() <what to place here>
elseif age(n)==30 & age(n)<=39
new_age_group2 = age() <what to place here>
end
end

madhan ravi on 12 Dec 2020
age = 1 : 40; % you were almost close, note: it could be done without loops
[new_age_group1, new_age_group2] = deal(cell(40, 1));
for n = 1 : numel(age)
if age(n) >= 10 && age(n) <= 29;
new_age_group1{n} = age(n);
elseif age(n) >= 30 && age(n) <= 39
new_age_group2{n} = age(n);
end
end
new_age_group1 = cat(1, new_age_group1{:})
new_age_group1 = 20×1
10 11 12 13 14 15 16 17 18 19
new_age_group2 = cat(1, new_age_group2{:})
new_age_group2 = 10×1
30 31 32 33 34 35 36 37 38 39

Geoff Hayes on 12 Dec 2020
Arturo - look closely at your conditions
if age(n)==10 & age(n)<=29
The above would mean that nth element of the age array is identical (==) to 10 and less than or equal to (<=) 29. This will only be true when age(n) is 10. Instead try
if age(n) >= 10 && age(n) <= 29
where age(n) is at least 10 and at most 29. You will need to do something similar for your other condition. As for grouping the ages, you might want to use a cell array where each element is an array of those ages that fit the condition. For example,
age_group = cell(5,1);
for n=1:length(age)
if age(n)>=10 && age(n)<=29
age_group(1) = [age_group{1} age(n)];
elseif age(n)>=30 && age(n)<=39
age_group(2) = [age_group{2} age(n)];
end
end
Arturo Jr. Ongkeko on 12 Dec 2020
Thanks very much Geoff! I get really confuse with loops and if-else so I am trying to be comfortable with it by implementing it in every opportunity I could even if there are other ways to do it. I want to develop my logic too in using these and the way you explain it really helped me a lot!