Plotting Timetable in Matlab

load_demand=readtable("Demand_timeseries_1hourResolution.xlsx");
TR=table2timetable(load_demand);
Time=TR({'05-05-2020','05-06-2020 00:00:00'},:);      
T = timetable2table(Time)  
x=T{2:end,1}
y=T{2:end,3}
plot(x,y)

I am trying to plot my timetable, but it will only plot a single point for it. So instead of plotting the whole data series for 'Time' it only plots for the first point. I tried converting it to an array but that didn't work out too well. Hopefully somebody can help me

Answer 1

[Anders Vigen]

https://se.mathworks.com/matlabcentral/answers/750099-plotting-timetable-in-matlab#comment_1344474

Answer 2

[Duncan Po]

The line:

Time=TR({'05-05-2020','05-06-2020 00:00:00'},:);

only extracts two rows from TR. So Time only has two rows. Then when you define x and y, the first row is discarded, so x and y are scalar. That's the reason only one point is plotted.

If you want the entire series, just use the entire TR instead of extracting only two rows.

[Anders Vigen]

@Duncan Po I don't want to plot TR because that gives me the data for a whole year, where as Time gives me a table containing the data between the two dates, and that's what I'm iterested in plotting.

[Walter Roberson]

https://www.mathworks.com/help/matlab/ref/timerange.html#d122e1343230

[Anders Vigen]

@Walter Roberson Hey, i tried playing around with the timerange, and now just gives me an error for below script.

load_demand=readtable("Demand_timeseries_1hourResolution.xlsx");
demand = load_demand(timerange(start_date:end_date,3));

However, it also gives me an extra error now

Error using timerange (line 128)
TIMERANGE endpoints must be datetime or duration scalars, or text representing datetime or duration scalars.

Am I setting up it incorrectly?

[Walter Roberson]

load_demand = readtable("Demand_timeseries_1hourResolution.xlsx");
TR = table2timetable(load_demand);
 subset = timerange(datetime('05-05-2020', 'InputFormat', 'MM-dd-yyyy'),datetime('05-06-2020 00:00:00', 'InputFormat', 'MM-dd-yyyy HH:mm:ss'));
Time = TR(subset,:);      
T = timetable2table(Time)  

x=T{2:end,1}
y=T{2:end,3}

plot(x,y)

By the way, why are you skipping the first row?

Note: using timerange would be a lot easier if you were using a standard way of representing the dates.

subset = timerange('2020-05-05', '2020-05-06')

The mess with calling datetime() with 'InputFormat' is only needed because month-day-year is not one of the recognized international time formats.

[Anders Vigen]

@Walter Roberson I think I'm close to getting it now. I just want my x array to also contain the hours from my T table, is that possible. Right now it is just a line at the date 05-05-2020, so it is taking all the values and plots it at the same date.

[Walter Roberson]

Should be okay provided that you have more than one hour of data being selected.

x = datetime('2020-05-05 00:00'):hours(1):datetime('2020-05-05 23:00');
y = rand(1,length(x));
plot(x, y)

[Anders Vigen]

@Walter Roberson how do I make the function for y use the values from column 3 of my T table? I have one value for each hour for the whole duration of may 5th.

[Walter Roberson]

load_demand = readtable("Demand_timeseries_1hourResolution.xlsx");
mask = isbetween(load_demand.Time, datetime('2020-05-05'), datetime('2020-05-06')-minutes(1));
x = load_demand.Time(mask);
y = load_demand{mask,3};
plot(x, y);

[Anders Vigen]

@Walter Roberson now it says

Unrecognized table variable name 'Time'.

Can the issue be that my Matlab is not up to date? I have the version 'MATLAB R2020b - academic use'

[Walter Roberson]

load_demand = readtable("Demand_timeseries_1hourResolution.xlsx");
mask = isbetween(load_demand{:, 1}, datetime('2020-05-05'), datetime('2020-05-06')-minutes(1));
x = load_demand.Time(mask);
y = load_demand{mask,3};
plot(x, y);

[Walter Roberson]

I do not have your file so I was guessing about the variable name based on some of your other comments in other posts.

[Anders Vigen]

@Walter Roberson when I use load_demand.Hours it gives me an error that say invalid plot. This refers to the column that only have hours. If I use load_demand.Date it plots of the data points for every hour of the 5th of may on a single line. load_demand.Date refers to the column only with dates. I think the real reason is that the datasheets dates and hours are sperated into two different column, and that is what gives the errors.

[Walter Roberson]

load_demand = readtable("Demand_timeseries_1hourResolution.xlsx");
load_demand.Time = load_demand.Date + hours(load_demand.Hours);
mask = isbetween(load_demand{:, 1}, datetime('2020-05-05'), datetime('2020-05-06')-minutes(1));
x = load_demand.Time(mask);
y = load_demand{mask,3};
plot(x, y);

[Walter Roberson]

This could have been resolved days ago if you have attached a sample file.

[Anders Vigen]

• Demand_timeseries_1hourResolution.xlsx

@Walter Roberson I do realise that now, and I'm sorry about that. I'm still quite new with Matlab and Mathworks. I attached the data file. The code you provided still gives an error, and I do believe it's due to that the hours in the datasheet is not numerical, I tried even to convert them to actual numbers but nothing happened.

[Walter Roberson]

The representation of hours turned out to be strange :(

load_demand = readtable("Demand_timeseries_1hourResolution.xlsx");
h = cellfun(@(S) sscanf(S, '%d', 1), load_demand.Hours);
load_demand.Time = load_demand.Date + hours(h);
mask = isbetween(load_demand{:, 1}, datetime('2020-05-05'), datetime('2020-05-06')-minutes(1));
x = load_demand.Time(mask);
y = load_demand{mask,3};
plot(x, y);

[Anders Vigen]

@Walter Roberson you are a genius! It worked completely as it should. Thank you very much for the dedication on this issue!

Answer 3

[xingxingcui]

Hi, @Anders Vigen

Here I give a Example:

tt = datetime+years(1:10); % 比如从现在时间开始，连续十年时间点
y = rand(10,1);
TT = timetable(tt',y)

TT = 10x1 timetable
            Time               y    
    ____________________    ________

    03-Jul-2025 07:22:39     0.73968
    03-Jul-2026 13:11:51     0.65843
    03-Jul-2027 19:01:03     0.83686
    03-Jul-2028 00:50:15     0.87343
    03-Jul-2029 06:39:27    0.074945
    03-Jul-2030 12:28:39     0.71392
    03-Jul-2031 18:17:51     0.67515
    03-Jul-2032 00:07:03     0.21619
    03-Jul-2033 05:56:15     0.28457
    03-Jul-2034 11:45:27    0.080194

plot(TT.Time,y,LineWidth=2)