code.js

/**
 * Simple Code.org JS app to find the closest Wi-Fi hotspot in NYC
 * Uses Code.org "NYC Public Wifi Locations" dataset
 * Uses about 9,000,000 traversals to sort the list of over 2,500 distances
 * @author John Brereton
 * @since 4/20/2021
 */

// Create lists to represent the dataset
var providerList = getColumn("NYC Public Wifi Locations", "Provider");
var locationList = getColumn("NYC Public Wifi Locations", "Location");
var latitudeList = getColumn("NYC Public Wifi Locations", "Latitude");
var longitudeList = getColumn("NYC Public Wifi Locations", "Longitude");
var accessList = getColumn("NYC Public Wifi Locations", "Access Location");
var boroughList = getColumn("NYC Public Wifi Locations", "Borough");
var neighborhoodList = getColumn("NYC Public Wifi Locations", "Neighborhood");
var zipList = getColumn("NYC Public Wifi Locations", "Postal Code");

// List to store the distance between each access point location and the user entered location
var distList = [];
var sortedIdList = [];

// Miles are now used for all distance calculations
// var distListMiles = [];

// Booleans that indicate wheather or not an error has been made when entering latitude and longitude
var latError;
var longError;

// Stores the results page currently being viewed
var resultsPage = 0;

// Stores the reference number of the location being viewed on the info page
var infoId;

// Stores the distance between the user entered lat and long and the item being traversed
var dist;

// Miles are now used for all distance calculations
// var distMiles;

// Finds and organizes the closest hotspots when the go button is clicked
onEvent("goButton", "click", function() {
    if(validateFields()) {
        setScreen("loadingScreen");
        generateDistList();
        sortedIdList = sortList(distList)[1];
        updateResults();
        setScreen("resultsScreen");
    }
});

// Returns to the home screen when the results screen back button is pressed
onEvent("resultsBackButton", "click", function() {
    setScreen("homeScreen");
    resultsPage = 0;
});

// Returns to the results screen when the info screen back button is pressed
onEvent("infoBackButton", "click", function() {
    setScreen("resultsScreen");
});

// Changes to the previous page when the previous arrow is clicked
onEvent("prevButton", "click", function() {
    if(resultsPage>0) {
        resultsPage--;
        updateResults();
    }
});

// Changes to the next page when the next arrow is clicked
onEvent("nextButton", "click", function() {
    if(resultsPage<512) {
        resultsPage++;
        updateResults();
    }
});

// On event for the first result
// Sets the info id and runs the function to update the info screen
onEvent("result0", "click", function() {
    infoId = (5*resultsPage);
    updateInfo();
    setScreen("infoScreen");
});

// On event for the second result
onEvent("result1", "click", function() {
    infoId = (5*resultsPage)+1;
    updateInfo();
    setScreen("infoScreen");
});

// On event for the third result
onEvent("result2", "click", function() {
    infoId = (5*resultsPage)+2;
    updateInfo();
    setScreen("infoScreen");
});

// On event for the fourth result
onEvent("result3", "click", function() {
    infoId = (5*resultsPage)+3;
    updateInfo();
    setScreen("infoScreen");
});

// On event for the fifth result
onEvent("result4", "click", function() {
    infoId = (5*resultsPage)+4;
    updateInfo();
    setScreen("infoScreen");
});

// Validates that the latitude and longitude values the user enters are valid
// Checks that they are not blank
// Checks that they are a number
// Checks that they are within the latitude and longitude of NYC
function validateFields() {
    // Verifies latitude input
    if(getText("latitudeInput") == "") {
        setProperty("latitudeWarning", "text", "This is a required field");
        latError = true;
    }
    else if(isNaN(getText("latitudeInput"))) {
        setProperty("latitudeWarning", "text", "Please enter a valid number");
        latError = true;
    }
    else if(getText("latitudeInput") > calcMaxMin(latitudeList)[0] || getText("latitudeInput") < calcMaxMin(latitudeList)[1]) {
        setProperty("latitudeWarning", "text", "Please enter a latitudinal value within NYC");
        latError = true;
    }
    else {
        latError = false;
        setProperty("latitudeWarning", "text", "");
    }

    // Verifies longitude input
    if(getText("longitudeInput") == "") {
        setProperty("longitudeWarning", "text", "This is a required field");
        longError = true;
    }
    else if(isNaN(getText("longitudeInput"))) {
        setProperty("longitudeWarning", "text", "Please enter a valid number");
        longError = true;
    }
    else if(getText("longitudeInput") > calcMaxMin(longitudeList)[0] || getText("longitudeInput") < calcMaxMin(longitudeList)[1]) {
        setProperty("longitudeWarning", "text", "Please enter a longitudinal value within NYC");
        longError = true;
    }
    else {
        longError = false;
        setProperty("longitudeWarning", "text", "");
    }

    // Returns weather or not the user made a mistake in entering their latitude and longitude
    if(latError == false && longError == false) {
        return true;
    }
    else {
        return false;
    }
}

// Calculates the maximum and minimum value of an list
// Returns values as an list
function calcMaxMin(calcList) {
    var max = calcList[0];
    var min = calcList[0];
    for(var i=0; i < calcList.length; i++) {
        if(calcList[i] > max) {
            max = calcList[i];
        }
        else if(calcList[i] < min) {
            min = calcList[i];
        }
    }
    return [max, min];
}

// Generates list of distances from the user in miles and coordinate values
function generateDistList() {
    var userLatitude = getText("latitudeInput");
    var userLongitude = getText("longitudeInput");
    for(var i = 0; i < providerList.length; i++) {
        // Old method, used latitude and longitude wihtout miles conversion
        // Since latitude and longitude are not equal measurements this method was not accurate
        // dist = Math.sqrt(Math.abs((Math.abs(userLatitude)-Math.abs(latitudeList[i])))+Math.abs((Math.abs(userLongitude)-Math.abs(longitudeList[i]))));
        // distList[i] = dist;

        // New method, converts latitude and longitude to miles
        dist = Math.round(Math.sqrt((Math.pow(Math.abs((userLatitude*69)-(latitudeList[i]*69)), 2)) + (Math.pow(Math.abs((userLongitude*54.6)-(longitudeList[i]*54.6)), 2)))*100)/100;
        distList[i] = dist;
    }
}

// Sorts list from least to greatest
// Returns list of sorted values and a list of their origional list ids
// Uses two for loops to go through every possible combination of two values in the list and see which one is greater
// If the larger number is in front of the smaller number their positions will be exchanged
function sortList(list) {
    var sortedList = [];
    var sortedIds = [];
    var temp = 0;
    sortedList = list;
    sortedIds = createNumericalList(0, list.length);
    for (var i = 0; i < sortedList.length; i++) {
        for (var j=i; j < sortedList.length; j++) {
            if (sortedList[j] < sortedList[i]) {
                temp = sortedIds[j];
                sortedIds[j] = sortedIds[i];
                sortedIds[i] = temp;

                temp = sortedList[j];
                sortedList [j] = sortedList[i];
                sortedList[i] = temp;
            }
        }
    }
    return [sortedList, sortedIds];
}

// Creates a list of consecutive integers
// Requires a starting(from) and ending(to) number
function createNumericalList(from, to) {
    var list = [];
    for (var i=from; i<=to; i++) {
        appendItem(list, i);
    }
    return list;
}

// Updates the results page
// Shows results in order from closest to furthest using the sorted id list
function updateResults() {
    for (var i=0; i<=4; i++) {
        setProperty("result" + i, "text", "Location: " + locationList[sortedIdList[(5*resultsPage)+i]] + " " + boroughList[sortedIdList[(5*resultsPage)+i]] +
                                        " NYC\nProvider: " + providerList[sortedIdList[(5*resultsPage)+i]]);
    }
    setProperty("pageLabel", "text", "Page: " + (resultsPage+1) + " of 513");
}

// Updates the info page
// Info id represents which button was clicked
// Sorted id list is used to make info corespond to correct button on results page
// Only takes the first 20 values of the string to prevent the string from expanding into a second line
function updateInfo() {
    setProperty("infoOutput", "text", distList[sortedIdList[infoId]] + " Miles" +
                                    "\n" + providerList[sortedIdList[infoId]] +
                                    "\n" + locationList[sortedIdList[infoId]].toString().substring(0, 20) +
                                    "\n" + accessList[sortedIdList[infoId]].toString().substring(0, 20) +
                                    "\n" + boroughList[sortedIdList[infoId]].toString().substring(0, 20) +
                                    "\n" + neighborhoodList[sortedIdList[infoId]].toString().substring(0, 20) +
                                    "\n" + zipList[sortedIdList[infoId]].toString().substring(0, 20));
}