MATLAB: Sorting data from table

datetable

Hi, I have a table T (8766×4) columns are – month, day, year and Flow rate (that is 24 years of data – 8766 days). I need to sort flow rate for each year separately and descend flow rate for each year and then plot.

P.S. I am afraid this approach with tables is wrong

Best Answer

T - your table with variables: month, day, year and prutok.

ii = findgroups(T.year);
Prutok = accumarray(ii,T.prutok,[],@(x){sort(x,'descend')});
for jj = 1:numel(Prutok), plot(Prutok{jj}); hold on; end

other variant

Days1 = day(datetime(T{:,{'year','month','day'}}),'dayofyear');
c = findgroups(T.year);
Anew = sort(accumarray([Days1,c],T.prutok,[],[],nan),'descend');
plot(Anew)

(added)

and the best variant by Guillaume and Peter

hold on
varfun(@(x)plot(sort(x,'descend')),T,'GroupingVariable','year','InputVariable','prutok');
hold off

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MATLAB: How to plot a heat map with three vectors

I have made some modifications. The heatmap below Shows highest temp. each hour of a month, for two years.

% creating table (i hope you are using new Version of matlab 
% which has table function, otherwise try dataset)
t1 = datetime(2016,01,1,8,0,0);
t2 = datetime(2018,01,1,8,0,0);
t = t1:hours(1):t2;
myTable = table(t',year(t'),month(t'),day(t'),hour(t'));
myTable.Properties.VariableNames = {'date' 'year' 'month' 'day' 'hour'};
a = 0;
b = 40;
r = (b-a).*rand(17545,1) + a;
myTable.temp = r;
% Create categorical arrays from the month 
% and hour columns of the table. 
% Then determine the unique months and hours 
% to use as labels along the x-axis and y-axis.
months = categorical(myTable.month);
hours = categorical(myTable.hour);
xlabels = categories(months);
ylabels = categories(hours);
%Determine the final size of the resulting 
%color data based on the number of unique months and hours. 
nummonths = numel(xlabels);
numhours = numel(ylabels);
%Convert the categorical months and hours arrays 
%into numeric indices to use with the accumarray function. 
%Compute the color data as the maximum temperature for each 
%month and hour combination using the accumarray function. 
%Use NaN for missing month and year combinations.
x = double(months);
y = double(hours);
temps = myTable.temp;
cdata = accumarray([y,x],temps,[numhours,nummonths],@max,NaN);
%Create the heatmap. Label the x-axis and y-axis with the 
%months and years, respectively. Color the heatmap cells 
%using the computed matrix data.
h = heatmap(xlabels,ylabels,cdata);

MATLAB: Please help!!!! Write a function that returns the number of days between dates

days_between_dates = @(month1,day1,year1,month2,day2,year2)...
                         abs(datenum(year1,month1,day1) - datenum(year2,month2,day2));

days_between_dates = @(month1,day1,year1,month2,day2,year2)...
                            abs(diff(datenum([year1,month1,day1;year2,month2,day2])));

use:

>> days_between_dates(10,12,2015,9,5,2016)
ans =
   329
>>

Best Answer

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MATLAB: How to plot a heat map with three vectors

MATLAB: Please help!!!! Write a function that returns the number of days between dates

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