Threshold exceedance, where and by how much

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Hi guys!
I would love your help on this one:
I have an excel file (see attached) which contains daily values of ozone for three stations (A, B, C). For every day I want to check whether any of these three stations exceed the daily threshold oh 100 μg/m3, which station has exceeded the threshold (if any), and by how many digits.
E.g., 01/01/2006, A, 2 μg/m3
Is there a simple way to do this?
Thanks in advance!!
PS. I'm on Matlab 2019

Accepted Answer

Steven Lord
Steven Lord on 1 Jun 2021
Assuming you're reading this data into a table array like this sample one:
load patients
T = table(LastName, Age, Height, Weight);
head(T)
ans = 8×4 table
LastName Age Height Weight ____________ ___ ______ ______ {'Smith' } 38 71 176 {'Johnson' } 43 69 163 {'Williams'} 38 64 131 {'Jones' } 40 67 133 {'Brown' } 49 64 119 {'Davis' } 46 68 142 {'Miller' } 33 64 142 {'Wilson' } 40 68 180
We can use logical indexing to determine who weighs over 150 pounds.
isOver150 = T.Weight > 150;
patientsOver150 = T(isOver150, :);
head(patientsOver150)
ans = 8×4 table
LastName Age Height Weight ____________ ___ ______ ______ {'Smith' } 38 71 176 {'Johnson' } 43 69 163 {'Wilson' } 40 68 180 {'Moore' } 28 68 183 {'Jackson' } 25 71 174 {'White' } 39 72 202 {'Martin' } 48 71 181 {'Thompson'} 32 69 191
You can see that the first two rows of T are included in patientsOver150 since their weights are 176 and 163 respectively. The next row in patientsOver150 is row 10 of T since rows 3-9 all represent patients with weights under 150. In both cases I'm only showing 10 rows of the tables, which is why the display of patientsOver150 has rows that don't appear in the display of T.
Now to see by how much the patients' weights exceed 150 pounds just compute with that table variable and assign to a new table variable:
patientsOver150.weightOver150 = patientsOver150.Weight - 150;
head(patientsOver150)
ans = 8×5 table
LastName Age Height Weight weightOver150 ____________ ___ ______ ______ _____________ {'Smith' } 38 71 176 26 {'Johnson' } 43 69 163 13 {'Wilson' } 40 68 180 30 {'Moore' } 28 68 183 33 {'Jackson' } 25 71 174 24 {'White' } 39 72 202 52 {'Martin' } 48 71 181 31 {'Thompson'} 32 69 191 41
  1 Comment
Daphne PARLIARI
Daphne PARLIARI on 2 Jun 2021
Thank you for the help!
The problem is that I have three columns that I want to check for exceedance, and the example works for one. Which means that I can't generate patientsOver150 for my data...
How can I solve this?

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