Load Highway Fatality Data

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

在这个例子中,我们探讨一些公路死亡data. Start by loading the data. The variables are shown as the column headers of the table.

loadfatalitiesfatalities(1:10,:)

ans=10×8 tablelongitude 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 theLive Editortab and click theSection Breakbutton. 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 ratedisp([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.

histogram(rate,10) 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 theLive Editortab, click theControlbutton, 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 figuresscatter(fatalities.(dataToPlot),rate)% Plot fatalities vs. selected variablexlabel(dataToPlot) ylabel('Percent Fatalities per Million Vehicle Miles') holdonxmin = min(fatalities.(dataToPlot)); xmax = max(fatalities.(dataToPlot)); p = polyfit(fatalities.(dataToPlot),rate,1);% Calculate & plot least squares lineplot([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.

loadusastates.matfigure geoplot([usastates.Lat], [usastates.Lon],'black') geobasemapdarkwaterholdongeoscatter(fatalities.latitude,fatalities.longitude,2000*rate,fatalities.urbanPopulation,'filled') c = colorbar; title(c,'Percent Urban')