How can I create a matrice with values over a number of this matrix ?

I have data of more than 18'000 earthquakes and I need to code a "for" loop that can find how many earthquakes >=7 occured.

I know how to use the loop, but I've no clue how to create a new matrice with all the earthquakes over 7 + a lign that counts them.

Thanks in advance !

Answer 1

[Star Strider]

Perhaps something like this —

earthquakes = rand(20,1)*9                          % Data (Richter Magnitudes)

earthquakes = 20×1

6.8914 8.6107 1.5547 8.8077 5.7766 2.5438 2.9706 7.1412 1.5764 8.5690

eq_gt7 = earthquakes>7                              % Logical Vector

eq_gt7 = 20×1 logical array
   0
   1
   0
   1
   0
   0
   0
   1
   0
   1
   1
   0
   0
   1
   0
   0
   0
   0
   0
   0

Nr_earthquakes_gt7 = nnz(eq_gt7)                    % Number Of Earthquakes > 7

Nr_earthquakes_gt7 = 6

earthquakes_gt7 = earthquakes(eq_gt7)               % Magnitudes Of Earthquakes > 7

earthquakes_gt7 = 6×1

8.6107 8.8077 7.1412 8.5690 7.7133 8.7649

.

[Luca]

Thanks a lot ! it works !

[Star Strider]

My pleasure!

If my Answer helped you solve your problem, please Accept it!

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