Sorting and Re-arranging a text file using Matlab by a specific column

I'm a newbie of Matlab world and learning a lot from this forum!!

But, I couldn't find the answer for my question at this moment.

"What I have in a text file"

• First row is a "Text" form
• Second to End is a "Number"
• Example in 10 rows by 3 column (and would like to expand over 1000 rows and column eventually)

Time ID Number

1 1 2

2 2 3

3 3 8

4 1 3

5 2 4

6 3 4

7 2 5

8 3 1

9 1 3

.........

"What I want to do"

• First, sort my text file by 'Second' column (called ID in my example)
• Second, re-arranging it by ID as it should be appeared as,
• Number of each ID may not be even, so I need some idea to cut the data at specific row at each ID.

Time ID Number

1 1 2

4 1 3

9 1 3

2 2 3

5 2 4

7 2 5

3 3 8

6 3 4

8 3 1

.........

• Then, I want to find the 'Max. value' and 'Sum' for each ID in a Text or as an output in Matlab as,

ID Max Sum

1 3 8

2 5 12

3 8 13

Your HELP will be very very appreciated!!!

Answer 1

[Stephen23]

T = readtable('test.txt')

T = 9×3 table
    Time    ID    Number
    ____    __    ______

     1      1       2   
     2      2       3   
     3      3       8   
     4      1       3   
     5      2       4   
     6      3       4   
     7      2       5   
     8      3       1   
     9      1       3   

T = sortrows(T,'ID')

T = 9×3 table
    Time    ID    Number
    ____    __    ______

     1      1       2   
     4      1       3   
     9      1       3   
     2      2       3   
     5      2       4   
     7      2       5   
     3      3       8   
     6      3       4   
     8      3       1   

G = findgroups(T.ID);
S = groupsummary(T,"ID",{"max","sum"},"Number");
S = removevars(S,'GroupCount');
S = renamevars(S,["max_Number","sum_Number"],["max","sum"])

S = 3×3 table
    ID    max    sum
    __    ___    ___

    1      3      8 
    2      5     12 
    3      8     13 

writetable(S,'summary.txt')