Problem stataments in Matlab

Hi,

I would like to make a problem statement in Matalb, here are 3 columns, the 1st column is the user ID, the 2nd is (A/B) and 3rd is the combinations of $ and NIC.

(1) I wanted to count (a) how many many times $ has been pressed in total (b) count multiple $ as once pressed only by each user and total number of it.

(2) And in column 2, i wanted to check how many times the NIC has been pressed before $ pressed (so, 1st pressed: NIC, 2nd pressed: $) and count the total number of users.

I haven't used the Matalb for so long, so i would like to know how to do it...

Tim

Answer 1

[Dyuman Joshi]

Final answer, I have tested this code on my laptop

cd=0; %counting $
userd=[];
for i=1:size(T,1)
    if isequal(char(T.Column2(i)),'$')
        cd=cd+1; %number of '$' has been pressed.
        userd=[userd char(T.Column1(i))];
    end
end
uniqued=numel(unique(userd))

cnic=0; %counting NIC before $
usernic=[];
for j=1:size(T,1)-1
    if isequal(char(T.Column2(j)),'NIC')&isequal(char(T.Column2(j+1)),'$')
        cnic=cnic+1;
        usernic=[usernic char(T.Column1(j))];
    end
end
uniquenic=numel(unique(usernic))

Answer 2

[Dyuman Joshi]

I'm assuming that the data in Column 1 and Column 2 is char/strings.

%T is your table
cd=0; %counting $
userd=[];
for i=1:size(T,1)
    if isequal(T.Column2(i),'$')
        countd=countd+1; %number of '$' has been pressed.
        userd=[userd T.Column1(i)];
    end
end
uniqued=numel(unique(userd));

cnic=0; %counting NIC before $
usernic=[];
for j=1:size(T,1)-1
    if isequal(T.Column2(i),'NIC')&isequal(T.Column2(i+1),'$')
        cnicbefd=cnicbefd+1;
        usernic=[usernic T.Column1(i)];
    end
end
uniquenic=numel(unique(usernic));

[ka chun yick]

I mean if the user has pressed it mutiple times, and i would like to count as one time only

[Dyuman Joshi]

I have edited my answer

[ka chun yick]

This maybe a stupid question. I have imported all the columns here, but it said Unrecognized function or variable "T" and Error on Untitled (line 4)

[ka chun yick]

On top of that, What do (T,1),(i,3) &(i,2) mean in the table?

[ka chun yick]

@Dyuman Joshi, apologise about that. I have deleted it. This is my second attampt. I have defined the T and here is the another error.

[Dyuman Joshi]

Can you show what the values in T are?

[ka chun yick]

If you look at the right-hand side i exported it from the excel. The table is exactly the same as the original post

[Dyuman Joshi]

I saw that. But I don't know what is the data type. Can you post the data here so I can try it myself directly?

[ka chun yick]

The excel is named as T

[Dyuman Joshi]

Okay, when you import T, what is the data type of Column 1 and 2? Char/string or categorical?

Asking because I am getting 2 different answers on based on method of importing.

[ka chun yick]

I think it is the simple char here from the excel

[Dyuman Joshi]

I have modified my code accordinly, please check.

Answer 3

[ka chun yick]

Hi, i got the following error, it said 'countd' is unrecognized......

Unrecognized function or variable 'countd'.

Error in Untitled (line 6)

countd=countd+1; %number of '$' has been pressed.

[Dyuman Joshi]

sorry, change cd=0 to countd=0.

[ka chun yick]

@Dyuman Joshi okay, it seems got far more problems once changing it....

Index exceeds the number of array elements (10).

Error in categorical/subsref (line 21)

b.codes = a.codes(s.subs{:});

Error in tabular/dotParenReference (line 108)

b = b(rowIndices);

Error in Untitled (line 14)

if isequal(T.Column2(i),'NIC')&isequal(T.Column2(i+1),'$')

[ka chun yick]

@Dyuman Joshi Any idea?

[Dyuman Joshi]

This is just a data type mismatch in the if condition statement. Check what the data type in table T, then you can edit accorindingly as well.

Answer 4

[ka chun yick]

@Dyuman Joshi. I am sure when i imported it from excel, it is a table as a whole. i have been reading some documents on how to converting type: https://uk.mathworks.com/help/matlab/data-type-conversion.html .But i still getting really confused on how to check the data and how to edit it from here, also the if condition statement..... Appologise for all the confusions......