ListView WPF中的Sum列

Question

I have the below csv file:

Name,Score
Kelly,5
James,5
Sara,1
Kelly,4
James,1
John,3

And I am trying to read the CSV file, get the sum of the Scores based on the Names and load them into the listview.

As a start, I was able to read the CSV file and load it into two listviews for each column. below is my code:

   public MainWindow()
    {
        InitializeComponent();      
        using (var fs = File.OpenRead(filepath))
        using (var reader = new StreamReader(fs))
        {
            List<string> list0 = new List<string>();
            List<string> list1 = new List<string>();
            while (!reader.EndOfStream)
            {
                var line = reader.ReadLine();
                var values = line.Split(',');

                list0.Add(values[0]);
                list1.Add(values[1]);
                 //sum = list1.Sum(x => Convert.ToInt32(x));
            }

            List0.ItemsSource = list0;
            List1.ItemsSource = list1; 

         }
  }

and here's the xaml code I used:

    <ListView Name="List0" HorizontalAlignment="Left" Height="258" Margin="0,33,0,0" VerticalAlignment="Top" Width="267" >
            <ListView.View>
                <GridView>
                    <GridViewColumn DisplayMemberBinding="{Binding}"/>
                </GridView>
            </ListView.View>
        </ListView>
        <ListView Name="List1" HorizontalAlignment="Left" Height="258"   Margin="272,33,0,0" VerticalAlignment="Top" Width="172" >
            <ListView.View>
                <GridView>
                    <GridViewColumn DisplayMemberBinding="{Binding}"/>
                </GridView>
            </ListView.View>
        </ListView>

And this is working fine with me. But I got stuck from here and I was wondering if it's possible to get the sum of the Score column based on the Names in the listview.

For example, get the total score of Kelly, get the total score of James etc. So the listview would look like this:

Name,Score
Kelly,9 
James,6 
Sara,1
John,3

I tried to use the Sum option and thought of printing it to a label to test, but it didn't work and i got an error saying "Input string was not in a correct format"

I am still not that experienced in C#, WPF and XAML; especially in reading and parsing CSV files so I am not sure how to go about this. Any help in this matter or pointers is much appreciated! Thank you!

Answer 1

I'd use a Dictionary:

public MainWindow()
{
    InitializeComponent();      
    using (var fs = File.OpenRead(filepath))
    using (var reader = new StreamReader(fs))
    {
        var dict = new Dictionary<string, int>();
        while (!reader.EndOfStream)
        {
            var line = reader.ReadLine();
            var values = line.Split(',');

            // Discard header line
            if (("Name" == values[0]) && ("Score" == values[1]))
                continue;

            if (dict.ContainsKey(values[0]))
                dict[values[0]] += Convert.ToInt32(values[1]);
            else
                dict[values[0]] = Convert.ToInt32(values[1]);
        }

        // Now you can create some lists to display
        var list0 = new List<string>();
        var list1 = new List<string>();
        foreach (KeyValuePair<string, string> entry in dict)
        {
            list0.Add(entry.Key);
            list1.Add(entry.Value.ToString());
        }

        List0.ItemsSource = list0;
        List1.ItemsSource = list1; 
     }
}

Answer 2

I would create a new class for storing the persons including their score. Something like this

public class Person
{
    public string Name { get; private set; }
    public int Score { get; set; }

    public Person(string name, int score)
    {
        Name = name;
        Score = Score;
    }
}

Then you could change your logic to something like this

var lines = File.ReadAllLines(filepath);
var persons = new List<Person>();

foreach(var line in lines)
{
    var values = line.Split(',');
    var name = values[0];
    var score = int.Parse(line[1].ToString());

    var person = persons.FirstOrDefault(x => x.Name == name);
    if(person == null)
    {
        var newPerson = new Person(name, score);
        persons.Add(newPerson);
    }
    else
    {
        person.Score += score;
    }
}

Advantage of a Person class is a cleaner and more understandable code; no magic strings where nobody knows what their value means.

In your logic you can raise the score of a person when you already have one entry for the person in your list.

//edit Binding to xaml You can use a DataGrid for example.

<DataGrid ItemsSource="{Binding Persons}" />

Persons is the ObservableCollection<Person> in your ViewModel. The DataGrid will automatically create one column for every property in your Person class. You could custommize your DataGrid to get the look you want. There are alot of examples in the internet.

//edit Binding The collection with the persons has to be public. Otherwise you could not access it from the xaml.

You could remove

var persons = new List<Person>();

And replace it with a property in your MainWindow class.

public ObservableCollection<Person> Persons {get; set;}

You class should look like

public ObservableCollection<Person> Persons {get; set;}

public MainWindow()
    {
        InitializeComponent();

        var lines = File.ReadAllLines(filepath);
        Persons = new ObservableCollection<Person>();

And in your DataGrid change the binding to ItemsSource="{Binding Persons}"