find maximum value for each year in a 2 columns array

I have an array with two columns, column one year (1975-2020) and column two discharge values. I need to find the maximum discharge amount for each year and have them saved in another matrix.

Can you please help me with this?

input:

1975 200

1975 85

.

.

.

2002 110

2002 95

2002 32

...

2020 120

...

desired output

1975 200

...

2002 110

...

2020 120

Answer 1

[Tommy]

Try this:

[G, y] = findgroups(input(:,1));
output = [y splitapply(@max, input(:,2), G)];

[Mahtab Moalemi]

Thanks but it gives me this error:

Error using splitapply (line 99)

The data variables must have the same number of rows as the vector of group numbers. The group number

vector has 46 row(s), and data variable 1 has 934768 row(s).

[Tommy]

Do you mind posting the code you ran which gave you this error?

[Mahtab Moalemi]

[years,groups] = findgroups(year_Q(:,1));

>> output = [years splitapply(@max, year_Q(:,2), groups)];

[Tommy]

Switch the outputs.

[groups, years] = findgroups(year_Q(:,1));
>> output = [years splitapply(@max, year_Q(:,2), groups)];

[Mahtab Moalemi]

nevermind! sorted it out

Thanks