MATLAB: Multiplying by the number of the day of each month in a cell arrays

cell arraysMATLAB

Hey all,
I have a 1 x 8 cell which includes tables. In each table, there is the date column and the results column. In each row, I want to multiply results values by the number of days in the month from the date column (considering leap and non-leap years).
For example:
date results new_results
———- ————- —————
1989-01-01 0.2 31 * 0.2 = 6.2
1989-02-01 0.8 30 * 0.8 = 24
. . .
. . .
. . .
2018-12-01 0.4 31*0.4 = 12.4
I read matlab help and tried to use this code:
calculations = arrayfun(@(x) test{x}.results*days(test{x}.date));
But it not working and say not enough inputs.
I attached my data. Any help is highly appreciated.
Thank you !

Best Answer

Try this: 
D = load('test.mat');
test = D.test;
T1 = test{1};                                           % Select Table #1 From 'test'
[yt,mt,dt] = ymd(T1.date);                              % Return: Year & Month

dim = eomday(yt,mt);                                    % Return: Days In Month

new_results = T1.results .* dim;                        % Create: 'new_results' Variable (Column)new_results’ Variable (Column)
T1.new_results = new_results;                           % Concatenate

producing for example: 
Check = T1(1:12,:)
Check =
  12×6 table
    model_name       date       lon    lat    results    new_results
    __________    __________    ___    ___    _______    ___________
    {'ERA5_1'}    1989-01-01    43     40     0.22701      7.0373   
    {'ERA5_1'}    1989-02-01    43     40     0.66383      18.587   
    {'ERA5_1'}    1989-03-01    43     40      1.4266      44.225   
    {'ERA5_1'}    1989-04-01    43     40      1.9511      58.534   
    {'ERA5_1'}    1989-05-01    43     40      1.6575      51.382   
    {'ERA5_1'}    1989-06-01    43     40      1.3122      39.367   
    {'ERA5_1'}    1989-07-01    43     40     0.86207      26.724   
    {'ERA5_1'}    1989-08-01    43     40      0.6105      18.926   
    {'ERA5_1'}    1989-09-01    43     40     0.77049      23.115   
    {'ERA5_1'}    1989-10-01    43     40      2.9392      91.114   
    {'ERA5_1'}    1989-11-01    43     40      3.2634      97.901   
    {'ERA5_1'}    1989-12-01    43     40      0.9547      29.596
There is an error in the ‘example’ in the posted Question. February has 28 (or 29) days, never 30.
EDIT — (22 Mar 2020 at 14:13)
This can easily be extended to all the tables in ‘test’: 
for k = 1:numel(test)
    Tk = test{k};                                       % Select Table From ‘test’
    VarEnd = numel(Tk.Properties.VariableNames)         % Retrieve: ‘VariableNames’
    [yt,mt,dt] = ymd(Tk.date);                          % Return: Year & Month
    DIM = eomday(yt,mt);                                % Return: Days In Month
    new_Val = Tk{:,VarEnd} .* DIM;                      % Create: ‘new_results’ Variable (Column)
    Tk{:,VarEnd+1} = new_Val;                           % Concatenate
    Tk.Properties.VariableNames{VarEnd+1} = ['new_' Tk.Properties.VariableNames{VarEnd}];
    test{k} = Tk;                                       % Save New Table To Previous Cell
end
The complexity arises because the last variable name in ‘test{1}’ is ‘results’ and in the rest it is ‘precip’. This accommodates every table regardless of what the last variable (column) name is.
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