# How do I save the output from a double for loop to a vector?

6 vues (au cours des 30 derniers jours)
matt beemsterboer le 25 Avr 2023
Commenté : dpb le 26 Avr 2023
Hi all,
I am trying to use a double for loop to count the number of patients admitted to a hospital (from a data set in excel) during each of the 24 hours in a day. I believe that the for loops are correct but I am unsure as to how I save the outputs (number of patients admitted each hour) in a vector?
counter = 0;
for n = 0:23
for i = 1:height(Exceldata)
if (duration(n,0,0) <= NUM_Time_Data(i)) & (NUM_Time_Data(i) <= duration(n,59,0))
counter = counter + 1;
end
end
VectorOfValues(n) = counter;
end
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### Réponse acceptée

dpb le 25 Avr 2023
counter = 0;
VectorOfValues=zeros(24,1); % preallocate
for n = 0:23
for i = 1:height(Exceldata)
if (duration(n,0,0) <= NUM_Time_Data(i)) & (NUM_Time_Data(i) <= duration(n,59,0))
counter = counter + 1;
end
end
VectorOfValues(n+1) = counter;
end
But, "the MATLAB way" to do this will eliminate both loops -- use histcounts or, better yet, put the Excel data into a Matlab table and use groupsummary with the time data turned into datetime or timeofday class. See the general doc on tables and processing by grouping variables; it'll be a big timesaver in the long run compared to going at it brute force for every little detail.
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matt beemsterboer le 26 Avr 2023
For my purposes, the counter must be within the first loop, not outside both of them. But I forgot that I had to preallocate an array of a certain size. Thank you for that.
dpb le 26 Avr 2023
Still, it would be far better to load the data into a more useful form for analyses...
tPatients=table(datetime(2020,randi([1 12],1000,1),randi([0 23],1000,1)), ...
hours(randi([0 23],1000,1))+minutes(randi([0 59],1000,1)), ...
AdmittingDate AdmittingTime _____________ _____________ 31-Dec-2019 00:35 31-Dec-2019 01:49 31-Dec-2019 02:32 01-Jan-2020 14:59 01-Jan-2020 19:45 02-Jan-2020 01:29 02-Jan-2020 10:09 02-Jan-2020 10:59
ans = 24×3 table
hour_AdmittingTime GroupCount Percent __________________ __________ _______ [00:00, 01:00) 33 3.3 [01:00, 02:00) 47 4.7 [02:00, 03:00) 50 5 [03:00, 04:00) 43 4.3 [04:00, 05:00) 43 4.3 [05:00, 06:00) 47 4.7 [06:00, 07:00) 26 2.6 [07:00, 08:00) 39 3.9 [08:00, 09:00) 49 4.9 [09:00, 10:00) 40 4 [10:00, 11:00) 56 5.6 [11:00, 12:00) 33 3.3 [12:00, 13:00) 43 4.3 [13:00, 14:00) 46 4.6 [14:00, 15:00) 33 3.3 [15:00, 16:00) 53 5.3

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