Splitting Data Into Intervals and Finding the cumulative value

a =

    1.0000   71.8700
    2.0000  136.1100
    3.0000  151.3500
    4.0000  139.1300
    5.0000  127.1900
    6.0000   70.5400
    7.0000   76.8900
    8.0000  113.1700
    9.0000   52.8000
   10.0000   29.6300
   11.0000   82.2000
   12.0000   99.7300
   13.0000   46.6200
   14.0000   78.9300
   15.0000   68.8000
   16.0000   35.7400
   17.0000   83.0200
   18.0000  105.4000
   19.0000   15.7200
   20.0000   13.6600
   21.0000   48.9600
   22.0000   43.8700
   23.0000    6.8100
   24.0000   39.3100
   25.0000   22.5900
   27.0000   77.1500
   29.0000   45.1900
   30.0000   17.2500
   34.0000  138.4000
   38.0000   86.2800

I have the vector "a", Column 1 is the duration (hours) Column 2 is the rainfall amount (mm) and i would like to the following processes:

1) This is to be applied for a duration of more than 6 hours

2) Divided the rainfall into equal amounts depending on the duration. eg) for the 6 hour duration, 70.54/6 = 11.76 and so on for the others

3) Find the cumulative curve and plot. eg) looking at the same 6 hour duration

Hour Rainfall Amount

1 11.76

2 23.52

3 35.08

4 46.84

5 58.6

6 70.36

I'm not sure if you would use a loop but in total there would be 24 curves developed

Answer 1

[Star Strider]

Try this —

a = [1.0000   71.8700
    2.0000  136.1100
    3.0000  151.3500
    4.0000  139.1300
    5.0000  127.1900
    6.0000   70.5400
    7.0000   76.8900
    8.0000  113.1700
    9.0000   52.8000
   10.0000   29.6300
   11.0000   82.2000
   12.0000   99.7300
   13.0000   46.6200
   14.0000   78.9300
   15.0000   68.8000
   16.0000   35.7400
   17.0000   83.0200
   18.0000  105.4000
   19.0000   15.7200
   20.0000   13.6600
   21.0000   48.9600
   22.0000   43.8700
   23.0000    6.8100
   24.0000   39.3100
   25.0000   22.5900
   27.0000   77.1500
   29.0000   45.1900
   30.0000   17.2500
   34.0000  138.4000
   38.0000   86.2800];

a2 = a(7:end,:);                                % Limit 'a'
NrSP = size(a2,1);                              % Number Of Subplots
r = floor(sqrt(NrSP));                          % Subplot Rows
c = ceil(NrSP/r);                               % Subplot Columns

figure
for k = 1:NrSP
    subplot(r,c,k)
    xv{k} = 1:a2(k,1);
    yv{k} = xv{k}*a2(k,2)/a2(k,1);
    plot(xv{k}, yv{k},'.-')
    grid
    xlim([0 a2(end,1)])                         % Same 'XLim' For All Plots
    ylim([0 max(a2(:,2))])                      % Same 'YLim' For All Plots
    title(sprintf('a(%d,:)',k+6))
end

.

[Queena Edwards]

This works just one adjustment. It has to be in a dimensionless form. So for each point of a plot i would have to divide by the total duration or total rainfall amount. Looking at the 6 hour example.

Hour                                    Rainfall Amount
        1                                 11.76
        2                                 23.52
        3                                 35.08
        4                                 46.84
        5                                 58.6
        6                                 70.36

I would plot the answers of the following

  Hour                                    Rainfall Amount
        1/6 = 0.2                     11.76/ 70.36 = 0.2
        2/6= 0.3                      23.52/70.36 = 0.3
        3/6 = 0.5                     35.08/70.36 = 0.5
        4/6 = 0.7                     46.84/70.36=0.7
        5/6 =0.8                       58.6/70.36=0.8
        6 /6=1                         70.36/70.36=1      

[Star Strider]

That is easy to fix —

a = [1.0000   71.8700
    2.0000  136.1100
    3.0000  151.3500
    4.0000  139.1300
    5.0000  127.1900
    6.0000   70.5400
    7.0000   76.8900
    8.0000  113.1700
    9.0000   52.8000
    10.0000   29.6300
    11.0000   82.2000
    12.0000   99.7300
    13.0000   46.6200
    14.0000   78.9300
    15.0000   68.8000
    16.0000   35.7400
    17.0000   83.0200
    18.0000  105.4000
    19.0000   15.7200
    20.0000   13.6600
    21.0000   48.9600
    22.0000   43.8700
    23.0000    6.8100
    24.0000   39.3100
    25.0000   22.5900
    27.0000   77.1500
    29.0000   45.1900
    30.0000   17.2500
    34.0000  138.4000
    38.0000   86.2800];

a2 = a(7:end,:);                                % Limit 'a'
NrSP = size(a2,1);                              % Number Of Subplots
r = floor(sqrt(NrSP));                          % Subplot Rows
c = ceil(NrSP/r);                               % Subplot Columns

figure
for k = 1:NrSP
    subplot(r,c,k)
    xv{k} = (1:a2(k,1))/a2(k,1);                % Normalise 'xv' To (0,1)
    yv{k} = xv{k}*a2(k,1)*a2(k,2)/a2(k,1);
    plot(xv{k}, yv{k},'.-')
    grid
    ylim([0 max(a2(:,2))])                      % Same 'YLim' For All Plots
    title(sprintf('a(%d,:)',k+6))
end

EDIT — (15 Mar 2022 at 10:50)

Deleted this line:

xlim([0 1]) % Same 'XLim' For All Plots

because with normalised ‘x’ values it is no longer necessary. Re-ran code.

.

[Queena Edwards]

Okay and can this also be done for the y axis?

[Star Strider]

It can, however I do not understand the reason, since normalising both axes effectively destroys the data being plotted.

a = [1.0000   71.8700
    2.0000  136.1100
    3.0000  151.3500
    4.0000  139.1300
    5.0000  127.1900
    6.0000   70.5400
    7.0000   76.8900
    8.0000  113.1700
    9.0000   52.8000
    10.0000   29.6300
    11.0000   82.2000
    12.0000   99.7300
    13.0000   46.6200
    14.0000   78.9300
    15.0000   68.8000
    16.0000   35.7400
    17.0000   83.0200
    18.0000  105.4000
    19.0000   15.7200
    20.0000   13.6600
    21.0000   48.9600
    22.0000   43.8700
    23.0000    6.8100
    24.0000   39.3100
    25.0000   22.5900
    27.0000   77.1500
    29.0000   45.1900
    30.0000   17.2500
    34.0000  138.4000
    38.0000   86.2800];

a2 = a(7:end,:);                                % Limit 'a'
NrSP = size(a2,1);                              % Number Of Subplots
r = floor(sqrt(NrSP));                          % Subplot Rows
c = ceil(NrSP/r);                               % Subplot Columns

figure
for k = 1:NrSP
    subplot(r,c,k)
    xv{k} = (1:a2(k,1))/a2(k,1);                % Normalise 'xv' To (0,1)
    yv{k} = xv{k}*a2(k,2)/a2(k,2);              % Normalise 'yv' To (0,1)
    plot(xv{k}, yv{k},'.-')
    grid
    title(sprintf('a(%d,:)',k+6))
end

.

[Queena Edwards]

Thank you for your help

[Star Strider]

As always, my pleasure!