Vectorization or Looping?

I'm trying to accomplish a task through vectorization rather than reverting to my old habit of looping. I have a table, T, imported from a text file. The table is comprised of a list of items with a variable number of subtotals associated with each item. Is it possible to return the sum of the subtotals for each item without looping?

For example, with T below:

Var1 Var2

Item 1 NaN

Subtotal 1 1.4

Subtotal 2 0.7

Subtotal 3 5.4

Item2 NaN

Subtotal 1 1.9

Item 3 NaN

Subtotal 1 2.4

Subtotal 2 3.6

Desired output:

v1 v2

Item 1 7.5

Item 2 1.9

Item 3 6.0

v1 = find(contains(T.Var1,'Item'));

v2 = ?

Thanks in advance to anyone who can help!

[Stephen23]

The data arrangement make this challenging. A much better arrangement of the table data would be like this:

item = [1;1;1;2;3;3];
subt = [1.4;0.7;5.4;1.9;2.4;3.6];
tbl = table(item,subt)

tbl = 6×2 table
    item    subt
    ____    ____

     1      1.4 
     1      0.7 
     1      5.4 
     2      1.9 
     3      2.4 
     3      3.6 

Then your task is simple:

out = groupsummary(tbl,"item",@sum)

out = 3×3 table
    item    GroupCount    fun1_subt
    ____    __________    _________

     1          3            7.5   
     2          1            1.9   
     3          2              6   

[Dave O]

Thank-you for directing me towards the group summary. This is exactly the functionality I needed.

Answer 1

[Image Analyst]

You forgot to attach your table. No one is going to type all that in when you could just give it to us in a .mat or text file.

In the meantime, check out findgroups, groupsummary, grpstats, and splitapply

If you have any more questions, then attach your data and code to read it in with the paperclip icon after you read this:

TUTORIAL: How to ask a question (on Answers) and get a fast answer

[Dave O]

Thank-you for directing me to these functions. These are what I needed to accomplish my task.