How does one display the fit line in this plot in this situation?

조회 수: 8(최근 30일)
alpedhuez
alpedhuez 2021년 8월 20일
댓글: alpedhuez 2021년 8월 21일
I have a timetable T with
T.date T.vistors T.sales
----------------------------------------
I draw a plot
yyaxis left
plot(T.date, T.visitors)
hold on
yyaxis right
plot(T.date, T.sales)
Now I want to add a regression line of T.sales = a + b*T.visitors on this plot.
But this situation seems to be more complex. How to proceed?

채택된 답변

Sulaymon Eshkabilov
Sulaymon Eshkabilov 2021년 8월 21일
T = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/717514/test.csv');
Warning: The DATETIME data was created using format 'MM/dd/uuuu' but also matched 'dd/MM/uuuu'.
To avoid ambiguity, supply a datetime format using SETVAROPTS, e.g.
opts = setvaropts(opts,varname,'InputFormat','MM/dd/uuuu');
fit_model = polyfit(T.Visitor, T.Sales,1);
TSales_Fit = polyval(fit_model,T.Visitor);
yyaxis left
plot(T.Date, T.Visitor, 'ro', 'markerfacecolor', 'c', 'markersize', 13)
hold on
yyaxis right
plot(T.Date, T.Sales, 'bs', 'markerfacecolor', 'y', 'markersize', 9)
hold on
plot(0:numel(TSales_Fit)-1,TSales_Fit, 'k-', 'linewidth', 2)
legend('Date vs. Visitors', 'Date vs. Sales', 'Fit model: Visitors vs. Sales', 'location', 'northwest')
grid on

추가 답변(1개)

Sulaymon Eshkabilov
Sulaymon Eshkabilov 2021년 8월 20일
You can use these additional steps to get the linear fit model and calculate its values, and then plot them.
fit_model = polyfit(T.visitors,T.sales,1);
TSales_Fit = polyval(fit_model,T.visitors);
yyaxis left
plot(T.date, T.visitors)
hold on
yyaxis right
plot(T.date, T.sales)
hold on
plot(T.visitors, TSales_Fit)
Note that your set x -axis is T.date and what you are trying to plot on top of that is T.visitors (x-axis) vs. Tsales_Fit (y-axis). There is a mismatch. Thus, it is more appropriate to compute fit model: DD=datenum(T.date); TSales_Fit = a + b*(DD-DD(1)+1); and plot the followings:
DD=datenum(T.date);
DD = DD-DD(1)+1;
fit_model = polyfit(DD,T.sales,1);
TSales_Fit = polyval(fit_model,DD);
yyaxis left
plot(T.date, T.visitors)
hold on
yyaxis right
plot(T.date, T.sales)
hold on
plot(T.date, TSales_Fit)
legend('Date vs. Visitors', 'Date vs. Sales', 'Fit model: Date vs. Sales', 'location', 'best')
  댓글 수: 3
alpedhuez
alpedhuez 2021년 8월 21일
I have attached a simple csv file. Thank you.

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