# Problem stataments in Matlab

5 views (last 30 days)
ka chun yick on 12 May 2022
Answered: Dyuman Joshi on 19 May 2022
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

Dyuman Joshi on 19 May 2022
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))

Dyuman Joshi on 12 May 2022
Edited: Dyuman Joshi on 13 May 2022
I'm assuming that the data in Column 1 and Column 2 is char/strings.
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));
Dyuman Joshi on 13 May 2022
I have modified my code accordinly, please check.

ka chun yick on 13 May 2022
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 on 18 May 2022
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.

ka chun yick on 19 May 2022
@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...... 