using multiple else if

hello i have this code

clc

clear all

close all

arrival=xlsread('tripinfo.xlsx','G:G');

depart_time=xlsread('tripinfo.xlsx','B:B');

for i = 1:1:91

if depart_time(i) < 100

mean_travel1 = 0;

mean_travel1 = mean_travel1 + mean(arrival(1:i,:));

elseif 100 < depart_time(i) < 200

mean_travel2 = 0 ;

mean_travel2 = mean_travel2 + mean(arrival(1:i,:));

elseif 200 < depart_time(i) < 300

mean_travel3 = 0 ;

mean_travel3 = mean_travel3 + mean(arrival(1:i,:));

elseif 300 < depart_time(i) < 400

mean_travel4 = 0 ;

mean_travel4 = mean_travel4 + mean(arrival(1:i,:));

elseif 400 < depart_time(i) < 500

mean_travel5 = 0 ;

mean_travel5 = mean_travel5 + mean(arrival(1:i,:));

else

mean_travel6 = 0 ;

mean_travel6 = mean_travel6 + mean(arrival(1:i,:));

end

end

and it didn't recognize mean_trravel3 and the other variables after that

why this happen

also my depart time is 91x1

[Stephen23]

"it didn't recognize mean_trravel3 and the other variables after that why this happen "

Answer: Bad data design.

After those IF/ELSEIFs you have no easy way to know which of those variables you have created or not, so you have no easy way to process them. Your bad data design painted you into a corner, where you will either need to add some flags or write some ugly slow meta-programming to know which variables you created. Either way, it will add complexity and slow down your code.

Solution: Do not force meta-data (e.g. pseudo-indices) into variable names. Use actual indexing.

If you had simply stored the data in arrays using indexing you would not have this problem: the array(s) that you preallocated before the loop would always exist after the loop, togerther with any data that you add to it/them. Using arrays and indexing is how MATLAB works best. You should use arrays and indexing.

https://www.mathworks.com/help/matlab/matlab_prog/preallocating-arrays.html

Answer 1

[Jonas]

the reason the variables are not recognized is, that the depending on your if clause, another variable is created (the created variable name depends on the if clause).

E.g. in your first if clause only the variable mean_travel1 is created, but not the variables mean_travel2 to 6

what me irritates is, that the content of all your if clauses is the same, e.g.

mean_travel2 = 0 ;
mean_travel2 = mean_travel2 + mean(arrival(1:i,:));

equals

mean_travel2 = 0 ;
mean_travel2 = 0 + mean(arrival(1:i,:));

equals

mean_travel2 = mean(arrival(1:i,:));

all other if clauses behave the same

[arash rad]

I new to matlab and because of this

My depart_time is from 0 to 520 and I divided it into five clauses so that I can, for example, sum all arrivals between 0 and 100 and mean them

but it only recognize first two

[arash rad]

I understand The answer

I should write statement in if clause like this

elseif 200 < depart_time(i) & depart_time(i) < 300