How to list through words in for loop.

Hello guys

I am trying to make a program that counts hours that i soend in work. I write them in following format:

sixj=[8,16.5]

Which means that on sixth of july I worked from 8 in the morning until 4:30pm. I need to count all days and apply conditions: 1. If it is after 17:00 the pay is +33% and if it is sunday, the pay is +45%. I do not want to write code for every individual day, rather i would like to use for loop to list through days and calculate it in the loop. Does anybody have any idea how I might be able to do it? Thank you very much.

[per isakson]

• What about the sixth of June?
• Regulars here oppose against squeezing data into names of variables
• Timetables, Time-stamped data in tabular form might be worth checking out

[Stephen23]

sixj=[8,16.5]

Do NOT put meta-data (e.g. the month and day) into the variable names! Accessing meta-data in variable names is fragile, complicated, buggy, hard-to-debug, obfuscated, inefficient code. Read this to know why it is a bad idea to put meta-data into variable names:

https://www.mathworks.com/matlabcentral/answers/225435-save-variable-as-string-from-user-input

Not only is it very fragile to put meta-data into variable names, accessing any variable names dynamically is slow, buggy, and highly inefficient:

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

You would be much better off putting all of your data into one array, and then using indexing. For example:

data = [2017,7,6,8,16.5];

Note how this can then easily be a matrix of all of your data. Working with matrices is highly efficient in MATLAB. You could also use a structure (which could be a non-scalar structure):

data.date  = [2017,7,6];
data.start = 8;
data.end   = 16.5;

Either of these will be much easier to work with that using ugly and buggy dynamic variable names.

PS: the name MATLAB comes from "MATrix LABoratory", and not from "Lets split the data up into thousands of separate variables and make our code complex, ugly, and slow": when you keep your data in matrices or arrays then you can write very simple, neat, and efficient MATLAB code.

[Kevin Syc]

This program is only intended to work from 6th of july until 8th of september.

[per isakson]

• Why Matlab rather than a spreadsheet?

Answer 1

[Stephen23]

When you put your data into one array then your calculations will be trivially easy. For example:

M = [...
    2017,07,06,08,16.5;...
    2017,07,07,09,12.0;...
    2017,07,08,10,18.7;...
    2017,07,09,07,16.2;...
    2017,07,10,07,19.9];
%  [yyyy,mm,dd,beg,end]

>> hours = diff(M(:,4:5),1,2)
hours =
        8.5
          3
        8.7
        9.2
       12.9
>> dtnum = datenum(M(:,1:3));
>> days  = weekday(dtnum);
>> issun = days==1 % detect sundays
issun =
   0
   0
   0
   1
   0
>> pay = 99;
>> hours.*~issun*pay % normal rate
ans =
      841.5
        297
      861.3
          0
     1277.1
>> hours.*issun*pay*1.45 % sunday rate
ans =
          0
          0
          0
     1320.7
          0

and we can add plots very simply too:

>> bar(vec,hours)
>> datetick('x','mmmdd')

etc, etc. Did you see what I did there? By making the data much simpler (using one numeric matrix), I made your difficult problem disappear entirely and wrote more working code is less time than it took you to write your question! How? By keeping the data together.

[Kevin Syc]

thank you very much. This way is far better :)

[Stephen23]

@Kevin Syc: Indeed it is! Come and ask any time you want more help :)