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Accelerate Exploratory Programming Using the Live Editor

The following is an example of how to use the Live Editor to accelerate exploratory programming. This example demonstrates how you can use the Live Editor to:

  • See output together with the code that produced it.

  • Divide your program into sections to evaluate blocks of code individually.

  • Include visualizations.

  • Experiment with parameter values using controls.

  • Summarize and share your findings.

Load Highway Fatality Data

The Live Editor displays output together with the code that produced it. To run a section, go to the Live Editor tab and select the Run Section button. You can also click the blue bar that appears when you move your mouse to the left edge of a section.

In this example, we explore some highway fatality data. Start by loading the data. The variables are shown as the column headers of the table.

load fatalities
ans=10×8 table
                            longitude    latitude    deaths    drivers    vehicles    vehicleMiles    alcoholRelated    urbanPopulation
                            _________    ________    ______    _______    ________    ____________    ______________    _______________

    Wyoming                  -107.56      43.033      164      380.18      671.53         9261              54              65.226     
    District_of_Columbia     -77.027      38.892       43      349.12       240.4         3742              12                 100     
    Vermont                  -72.556      44.043       98      550.46      551.52         7855              20              38.196     
    North_Dakota               -99.5      47.469      100      461.78      721.84         7594              35              55.807     
    South_Dakota             -99.679      44.272      197       563.3      882.77         8784              76              51.923     
    Delaware                 -75.494      39.107      134      533.94      728.52         9301              48              80.021     
    Montana                  -110.58      46.867      229      712.88      1056.7        11207             100              54.031     
    Rhode_Island             -71.434      41.589       83      741.84       834.5         8473              41              90.936     
    New_Hampshire            -71.559      43.908      171      985.77      1244.6        13216              51              59.181     
    Maine                    -69.081      44.886      194      984.83      1106.8        14948              58              40.206     

Calculate Fatality Rates

The Live Editor allows you to divide your program into sections containing text, code, and output. To create a new section, go to the Live Editor tab and click the Section Break button. The code in a section can be run independently, which makes it easy to explore ideas as you write your program.

Calculate the fatality rate per one million vehicle miles. From these values we can find the states with the lowest and highest fatality rates.

states = fatalities.Properties.RowNames;
rate = fatalities.deaths./fatalities.vehicleMiles;
[~, minIdx] = min(rate);                  % Minimum accident rate
[~, maxIdx] = max(rate);                  % Maximum accident rate
disp([states{minIdx} ' has the lowest fatality rate at ' num2str(rate(minIdx))])
Massachusetts has the lowest fatality rate at 0.0086907
disp([states{maxIdx} ' has the highest fatality rate at ' num2str(rate(maxIdx))])
Mississippi has the highest fatality rate at 0.022825

Distribution of Fatalities

You can include visualizations in your program. Like output, plots and figures appear together with the code that produced them.

We can use a bar chart to see the distribution of fatality rates among the states. There are 11 states that have a fatality rate greater than 0.02 per million vehicle miles.

xlabel('Fatalities per Million Vehicle Miles')
ylabel('Number of States')

Find Correlations in the Data

You can explore your data quickly in the Live Editor by experimenting with parameter values to see how your results will change. Add controls to change parameter values interactively. To add controls, go to the Live Editor tab, click the Control button, and select from the available options.

We can experiment with the data to see if any of the variables in the table are correlated with highway fatalities. For example, it appears that highway fatality rates are lower in states with a higher percentage urban population.

dataToPlot = "urbanPopulation";
close                                      % Close any open figures
scatter(fatalities.(dataToPlot),rate)         % Plot fatalities vs. selected variable
ylabel('Percent Fatalities per Million Vehicle Miles') 

hold on
xmin = min(fatalities.(dataToPlot));
xmax = max(fatalities.(dataToPlot));
p = polyfit(fatalities.(dataToPlot),rate,1);  % Calculate & plot least squares line
plot([xmin xmax], polyval(p,[xmin xmax]))

Plot Fatalities and Urbanization on a US Map

Summarize your results and share your live script with your colleagues. Using your live script, they can recreate and extend your analysis. You can also save your analysis as HTML, Microsoft® Word, or PDF documents for publication.

Based on this analysis, we can summarize our findings using a plot of fatality rates and urban population on a map of the continental United States.

load usastates.mat
geoplot([usastates.Lat], [usastates.Lon], 'black')
geobasemap darkwater
hold on
c = colorbar;
title(c,'Percent Urban')

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