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# Extract changes on a string

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Arthur Romeu on 8 Jan 2020
Commented: Star Strider on 10 Jan 2020
Hello everyone,
I am trying to come up with a solution for the following:
I have two vars with the same size: "status" and "dates". "status" refers to different status on an equipment, and I need only the cells where a change in status occurs. Let me illustrate
'Online' %01
'Online' %02
'Online' %03
'Online' %04
'Online' %05
'Online' %06
'Offline' %07
'Offline' %08
'Offline' %09
'Offline' %10
'Offline' %11
'Offline' %12
I need to extract from a list like this only lines like 06 and 07, which is the last entry of one status and the first entry of the other. However, it's not just that. I also have the "dates" on datetime, and they all correspond with each cell on "status". So in order to preserve the date information of each cell, I need to, in this example, get the information on lines 06 and 07 of the "status" list and also the date on lines 06 and 07 of the "dates" list.
I have no idea of where to begin with this code :(
I hope I explained everything as clearly as possible. I'm sending the referred lists as an attachment for better understanding.
Thanks in advance,
Arthur.

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### Accepted Answer

Star Strider on 8 Jan 2020
Edited: Star Strider on 9 Jan 2020
Try this:
D1 = load('status.mat');
D2 = load('dates.mat');
status = string(D1.fontes);
datestimes = D2.data_tracking_tratado;
StatG = findgroups(status); % Create Numeric Labels For States
GrpID = unique(StatG); % Unique Labels
Trns = nchoosek(GrpID, 2); % Combinations Of All Status Changes
Trns = [Trns; fliplr(Trns)]; % Combinations Of All Status Changes
for k = 1:size(Trns,1)
StChng{k,:} = strfind(StatG.', Trns(k,:)); % First Index Of Status Changes — Indices Into Both ‘status’ & ‘datestimes’|
StChngIx{k,:} = Trns(k,:); % Associated Numeric Vector (Information Only)
end
StChngNE = cellfun(@(x) ~isempty(x), StChng); % Index To Delete Empty Entries
StChng = StChng(StChngNE); % Delete Empty Entries
StChngIx = StChngIx(StChngNE); % Delete Empty Entries
for k = 1:size(StChng,1) % Loop To Create Output Cell Arrays
Idx = StChng{k,1};
Out{1,k} = status(Idx);
Out{2,k} = status(Idx+1);
Out{3,k} = datestimes(Idx);
Out{4,k} = datestimes(Idx+1);
end
Other options, such as combining these into a table are also possible.
EDIT — (8 Jan 2020 at 21:45)
Added table code:
Outt = Out.'; % Transpose To (Nx4)
Status = [];
DatesTimes = [];
for k = 1:size(Outt,1)
Status = [Status; Outt{k,[1 2]}];
DatesTimes = [DatesTimes; Outt{k,[3 4]}];
end
StatusChanges = table(Status(:,1), Status(:,2), DatesTimes(:,1), DatesTimes(:,2), 'VariableNames',{'Status 1','Status 2','Time 1','Time 2'})
Producing:
StatusChanges =
Status 1 Status 2 Time 1 Time 2
____________ ____________ ____________________ ____________________
"Offline" "Soft Start" 01-Jan-2020 16:18:00 01-Jan-2020 16:19:00
"Offline" "Soft Start" 02-Jan-2020 12:34:00 02-Jan-2020 12:35:00
"Offline" "Test" 03-Jan-2020 09:02:00 03-Jan-2020 09:03:00
"Soft Start" "Test" 03-Jan-2020 09:55:00 03-Jan-2020 09:56:00
"Online" "Offline" 01-Jan-2020 12:15:00 01-Jan-2020 12:16:00
"Online" "Offline" 02-Jan-2020 08:23:00 02-Jan-2020 08:24:00
"Online" "Offline" 03-Jan-2020 05:50:00 03-Jan-2020 05:51:00
"Soft Start" "Online" 01-Jan-2020 16:39:00 01-Jan-2020 16:40:00
"Soft Start" "Online" 02-Jan-2020 13:06:00 02-Jan-2020 13:07:00
"Soft Start" "Online" 03-Jan-2020 10:52:00 03-Jan-2020 10:53:00
"Test" "Soft Start" 03-Jan-2020 09:52:00 03-Jan-2020 09:53:00
"Test" "Soft Start" 03-Jan-2020 10:31:00 03-Jan-2020 10:32:00
EDIT — (9 Jan 2020 at 02:10)
Corrected typographical errors.

#### 2 Comments

Arthur Romeu on 10 Jan 2020
Thanks a lot!!!
Seriousely man, you are very smart. Thanks for saving me. For how long have you been programming?
Star Strider on 10 Jan 2020
As always, my pleasure!
I very much appreciate your compliment!
I’ve been programming on and off for a while. I took my first course in FORTRAN as an undergraduate in 1968, and was introduced to MATLAB in 1994. (I also had a career as a physician and biomedical engineer, now retired from both.)
I noticed that the rows are not chronological. To sort them by ‘Time 1’, add this line after the ‘StatusChanges’ table assignment:
StatusChanges = sortrows(StatusChanges,{'Time 1'});
Producing:
StatusChanges =
Status 1 Status 2 Time 1 Time 2
____________ ____________ ____________________ ____________________
"Online" "Offline" 01-Jan-2020 12:15:00 01-Jan-2020 12:16:00
"Offline" "Soft Start" 01-Jan-2020 16:18:00 01-Jan-2020 16:19:00
"Soft Start" "Online" 01-Jan-2020 16:39:00 01-Jan-2020 16:40:00
"Online" "Offline" 02-Jan-2020 08:23:00 02-Jan-2020 08:24:00
"Offline" "Soft Start" 02-Jan-2020 12:34:00 02-Jan-2020 12:35:00
"Soft Start" "Online" 02-Jan-2020 13:06:00 02-Jan-2020 13:07:00
"Online" "Offline" 03-Jan-2020 05:50:00 03-Jan-2020 05:51:00
"Offline" "Test" 03-Jan-2020 09:02:00 03-Jan-2020 09:03:00
"Test" "Soft Start" 03-Jan-2020 09:52:00 03-Jan-2020 09:53:00
"Soft Start" "Test" 03-Jan-2020 09:55:00 03-Jan-2020 09:56:00
"Test" "Soft Start" 03-Jan-2020 10:31:00 03-Jan-2020 10:32:00
"Soft Start" "Online" 03-Jan-2020 10:52:00 03-Jan-2020 10:53:00
The ‘StatusChanges’ table is now sorted chronologically!

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