Imagine a list of objects:
public class Foo
{
public string Name {get; set;}
public int Total {get; set;}
}
And now, my list contains 3 objects:
new Foo {Name="object", Total=3};
new Foo {Name="object", Total=7};
new Foo {Name="object", Total=5};
How to distinct by the name and sum the totals? i.e. The List will have just one object:
new Foo {Name="object", Total=15};
Thanks in advance!
You can do this:
var newTotalList = yourList.GroupBy(x => x.Name)
.Select(x => new
{
Name = x.Key,
Total = x.Sum(y => y.Total)
})
.ToList();
What this code does is, simply, first group the elements by name, and then sum the Total fields of all the elements inside the group.
You should be able to use grouping.
var groupedList = (from ol in objectList
group ol by ol.Name
into grp
select new foo
{
Name = grp.Key,
Total= grp.Sum(ex => ex.Total),
City = grp.Select(ex => ex.City).FirstOrDefault(),
Country = grp.Select(ex => ex.Country ).FirstOrDefault(),
Phone = grp.Select(ex => ex.Phone).FirstOrDefault()
}
).ToList();
You can group by Name and then just sum up by Total:
var l = new List<Object>
{
new Object {Name="object", Total=3},
new Object {Name="object", Total=7},
new Object {Name="object", Total=5}
};
var result = l.GroupBy(o => o.Name)
.Select (grp => new Object
{
Name = grp.Key,
Total = grp.Sum(o => o.Total)
});
result is now:
Try this:
List<Object> list = ... // make a list somehow
var totalsPerName = list
.GroupBy(o => o.Name)
.Select(group => new Object { Name = group.Key, Total = group.Sum(o => o.Total) })
Group your elements by Name, and then for each group, select a new object whose name is name value grouped by for this group, and Total is the sum of all Totals in the group:
var groupdObject =list
.GroupBy(o =>o.Name)
.Select(g =>
new
{
Name = g.Key,
Total = g.Sum(o=>o.Total)
});
Related
I have this class:
public class tempClass
{
public int myKey { get; set; }
public int total { get; set; }
}
Code to group by and sum:
var list = new List<tempClass>();
list.Add(new tempClass { myKey = 1, total = 1 });
list.Add(new tempClass { myKey = 1, total = 2 });
list.Add(new tempClass { myKey = 2, total = 3 });
list.Add(new tempClass { myKey = 2, total = 4 });
list = list
.Select(w => new tempClass { myKey = w.myKey, total = w.total })
.GroupBy(x => new tempClass { myKey = x.myKey })
.Select(y => new tempClass { myKey = y.Key.myKey, total = y.Sum(z => z.total) })
.ToList();
The list count is still 4 after the GroupBy.
Same result for code below:
list = list
.GroupBy(x => new tempClass { myKey = x.myKey })
.Select(y => new tempClass { myKey = y.Key.myKey, total = y.Sum(z => z.total) })
.ToList();
The reason for this is that you group by a class which doesn't override Equals and GetHashCode. Then the implementation of System.Object is used which just compares references. Since all are different references you get one group for every instance.
You could group by this property or override Equals and GetHashCode to compare this property:
list = list
.Select(w => new tempClass { myKey = w.myKey, total = w.total })
.GroupBy(x => x.myKey)
.Select(y => new tempClass { myKey = y.Key, total = y.Sum(z => z.total) })
.ToList();
You don't need two Select lines, one is enough. And inside GroupBy, just select your key, don't create a new object of your class there:
list = list
.GroupBy(x => x.myKey)
.Select(y => new tempClass { myKey = y.Key, total = y.Sum(z => z.total) })
.ToList();
And here's the declarative-query-syntax version:
list = (from x in list
group x by x.myKey into g
select new tempClass { myKey = g.Key, total = g.Sum(z => z.total) }).ToList();
My, you are creating a lot of new TempClass objects in your LINQ statement, don't you?
The reason that you don't get the correct result is that your GroupBy doesn't make groups of TempClass objects with the equal TempClass.MyKey, but with equal TempClass.
The default EqualityComparer for TempClass declares two TempClass objects equal if they are the same object, thus making two TempClass objects unequal, even if they have the same values.
Your query should be:
var result = list
.GroupBy(listItem => listItem.MyKey) // make groups with equal MyKey
.Select(group => new // from every group make one new item
{
Key = group.Key, // with key the common MyKey in the group
GrandTotal = group.Sum(groupItem => groupItem.Total);
// and value the sum of all Total values in the group
});
I chose not to make the final resulting items a sequence of TempClasses, because I'm not sure if you would consider items with this GrandTotal as TempClass objects. But if you want, you could change the final select:
.Select(group => new TempKey()
{
Key = group.Key,
Total = group.Sum(groupItem => groupItem.Total);
});
I have an array of orders within each order is an array of items. How do I group all the orders by item name and get the sum total of items ordered. In this case output would be :
Output
Item01 : quantity = 2;
Item02 : quantity = 45;
GetOrders
public Order[] GetOrders()
{
Order[] orders = new Order[]
{
new Order
{
id = 1,
orderLines = new OrderLine[]
{
new OrderLine
{
itemName = "Item 01",
quantity = 1
},
new OrderLine
{
itemName = "Item 02",
quantity = 3
},
},
},
new Order
{
id = 2,
orderLines = new OrderLine[]
{
new OrderLine
{
itemName = "Item 01",
quantity = 1
},
new OrderLine
{
itemName = "Item 02",
quantity = 42
}
}
}
};
...
I tried the following:
foreach (var order in orders)
{
foreach (var orderline in order.orderLines.GroupBy(x => x.itemName).Select(group => new
{
Metric = group.Key,
Count = group.Count()
}))
{
Console.WriteLine("{0} {1}", orderline.Metric, orderline.Count);
}
}
but it just returns 1 for each item. I am relatively new to programming , so be easy on me.Thanks
To get the sum total of all items ordered, use the following query:
var results =
(from order in orders
from orderLine in order.orderLines
group orderLine by orderLine.itemName into orderLineGrouping
let totalQuantity = orderLineGrouping.Sum(ol => ol.quantity)
select new { itemName = orderLineGrouping.Key, metric = totalQuantity }).ToList();
results.ForEach(resultItem => Console.WriteLine("{0} {1}", resultItem.itemName, resultItem.metric);
Flatten orderlines
group the item name and quantities for output string
Select the output string using grouped key and sum of grouped quantities
See code:
var output = orders.SelectMany(x => x.orderLines)
.GroupBy(x => x.itemName, x => x.quantity)
.Select(x => $"{x.Key} : quantity = {x.Sum(y => y)}");
Flatten OrderLines
You need to familiarise your self with Enumerable.SelectMany its one of the most useful methods around
SelectMany, from LINQ, collapses many elements into a single
collection. The resulting collection is of another element type. We
specify how an element is transformed into a collection of other
elements.
var summary = orders.Where(x => x.OrderLines != null) // Check for null as there seems to be null orderlines in your model
.SelectMany(x => x.OrderLines) // Flatten
.GroupBy(x => x.itemName) // Group
.Select(group => new // Project
{
ItemName = group.Key,
TotalQuantity = group.Sum(x => x.quantity)
})
.ToList(); // To List
Tip : use appropriate casing for itemName and quantity
Capitalization Conventions
The following table summarizes the capitalization rules for
identifiers and provides examples for the different types of
identifiers.
Sorry my OCD just kicked in
I have a linq query like followin:
var _transactionsList = TransactionsData
.GroupBy(x => new { x.ItemID, x.Title, x.GalleryURL })
.Select(pr => new TransactionsTabResults
{
ItemID = pr.Key.ItemID,
Title = pr.Key.Title,
GalleryURL = pr.Key.GalleryURL,
ItemPrice = pr.OrderByDescending(a => a.TransactionDate).First().ItemPrice,
TotalSoldItems = pr.Count(),
TotalRevenuePerItem = pr.Sum(y => y.ItemPrice),
AveragePrice = pr.Average(y => y.ItemPrice),
}).ToList();
I'm trying to fetch the total sold items value by grouping it by like this:
ItemID Sales ItemName
1 1 Item1
1 3 Item1
1 5 Item1
1 6 Item1
2 2 Item2
2 2 Item2
2 2 Item2
2 2 Item2
The desired output would be:
ItemID Sales ItemName
1 15 Item1
2 8 Item2
The query above that I wrote gives me wrong values for total sales by saying:
TotalSoldItems = pr.Count(),
How can I count, or sum all the sales of one Item which has unique ID(this is what I'm grouping by)...
What am I doing wrong??
You are using GroubBy wrong way. You create new unique object every time. So your .GroupBy(x => new { x.ItemID, x.Title, x.GalleryURL }) and .Select(x => new { Key = new { x.ItemID, x.Title, x.GalleryURL}, Value =x }) means the same
If you need unique Id then group by Id only
TransactionsData
.GroupBy(x => x.ItemID)
.Select(pr => new TransactionsTabResults
{
ItemID = pr.Key,
Title = pr.First().Title,
GalleryURL = pr.First().GalleryURL,
ItemPrice = pr.OrderByDescending(a => a.TransactionDate).First().ItemPrice,
TotalSoldItems = pr.Count(),
TotalRevenuePerItem = pr.Sum(y => y.ItemPrice),
AveragePrice = pr.Average(y => y.ItemPrice),
}).ToList();
Advice
Optimize your LINQ. You are iterating through collections many times. This is suggested code:
TransactionsData
.GroupBy(x => x.ItemID)
.Select(pr =>
{
var items = x.pr.ToArray;
var sum = items.Sum(y => y.ItemPrice);
return new TransactionsTabResults
{
ItemID = pr.Key,
Title = items[0].Title,
GalleryURL = items[0].GalleryURL,
ItemPrice = pr.Aggregate((max, cur)=>max.TransactionDate<cur.TransactionDate?cur:max).ItemPrice,
TotalSoldItems = items.Length,
TotalRevenuePerItem = sum,
AveragePrice = sum/items.Length,
};
}).ToList();
I have a list of anonymous objects generated by a LINQ query that I do not have access to modify.
The objects have the following properties:
OrderId, RepId, FirstName, LastName, Address
Each "Rep" often places multiple orders, so there are a lot of rows where the only difference is the OrderId. There is a requirement that if the same Rep has placed multiple orders, to batch these together in groups of 6 with a new structure:
OrderId1, OrderId2, ..., OrderId6, RepId, FirstName, LastName, Address
But if the rep has placed say 8 orders, there would be a batch of 6 and a batch of 2. So the new objects don't always have the same number of properties.
I've started by grouping the initial result set by RepId, but I have no clue where to go next.
Is this possible using LINQ?
As your output have anonymous objects with different schema, that make the thing a little more complicate.
Ideally you should design your entity class to use list for orders instead of property like "OrderId1", "OrderId2"... That is not extensible and error prone. But for that specific question, we can combine LINQ and ExpandoObject to achieve this.
orders.GroupBy(order => order.RepId)
.SelectMany(orderGroup => orderGroup.Select((order, i) => new {
Order = order,
ReqId = orderGroup.Key,
SubGroupId = i / 6
}))
.GroupBy(h => new {
ReqId = h.ReqId,
SubGroupId = h.SubGroupId,
FirstName = h.Order.FirstName,
LastName = h.Order.LastName,
Address = h.Order.Address
})
.Select(orderWithRichInfo => {
dynamic dynamicObject = new ExpandoObject();
int i = 1;
foreach(var o in orderWithRichInfo)
{
((IDictionary<string, object>)dynamicObject).Add("OrderId" + i, o.Order.OrderId);
i++;
}
((IDictionary<string, object>)dynamicObject).Add("FirstName", orderWithRichInfo.Key.FirstName);
((IDictionary<string, object>)dynamicObject).Add("LastName", orderWithRichInfo.Key.LastName);
((IDictionary<string, object>)dynamicObject).Add("Address", orderWithRichInfo.Key.Address);
return dynamicObject;
});
Hope it helps.
First option.
If you want to get 6 OrderId-s as a list, you can create
class OrderBundle
{
public int RepId { get; set; }
public List<int> OrderIds { get; set; }
}
Group your items:
var orderBundels = orderList
.GroupBy(m => m.RepId)
.Select(g => new OrderBundle
{
RepId = g.Key,
OrderIds = g.Select(m => m.OrderId).ToList()
});
And then split them into groups:
List<OrderBundle> dividedOrderBundels = new List<OrderBundle>();
foreach (OrderBundle orderBundle in orderBundels)
{
int bundelCount = (int)Math.Ceiling(orderBundle.OrderIds.Count() / 6.0);
for (int i = 0; i < bundelCount; i++)
{
OrderBundle divided = new OrderBundle
{
RepId = orderBundle.RepId,
OrderIds = orderBundle.OrderIds.Skip(i * 6).Take(6).ToList()
};
dividedOrderBundels.Add(divided);
}
}
Second option:
You can achieve the same result without creating model like below:
var result = orderList
.GroupBy(m => m.RepId)
.SelectMany(g => g.Select((m, i) => new
{
RepId = g.Key,
FirstName = m.FirstName,
LastName = m.LastName,
Address = m.Address,
OrderId = m.OrderId,
BunleIndex = i / 6
}))
.GroupBy(m => m.BunleIndex)
.Select(g => new
{
RepId = g.Select(m => m.RepId).First(),
FirstName = g.Select(m => m.FirstName).First(),
LastName = g.Select(m => m.LastName).First(),
Address = g.Select(m => m.Address).First(),
OrderIds = g.Select(m => m.OrderId).ToList()
})
.ToList()
I have a list in my code that I need to filter through and return specific rows based on two criteria. The List in question is a list of models from a database. There are two ID properties on each model, one is the ID from the data table and is unique, the other is an ID we use to identify groups and can repeat. We'll call them ID and GroupID. Basically, I want the resulting list to have only one of each GroupID, and it should be the one with the highest (numerically speaking) ID. For example:
Input:
List<MyModel> modelList = new List<MyModel>
modelList[0].ID = 1 modelList[0].GroupID = 5
modelList[1].ID = 2 modelList[1].GroupID = 5
modelList[2].ID = 3 modelList[2].GroupID = 6
modelList[3].ID = 4 modelList[3].GroupID = 6
Desired Output:
Models at indexes 1 and 3.
Using LINQ:
var items = (from model in modelList
group model by model.GroupID into modelGroup
select modelGroup.Max(i => i.ID)).ToList();
What you have to do here is first order the modelList by ID and then GroupBy the list items by GroupID, then pull the item with max Id value.
var result = modelList.OrderByDescending(x => x.ID).GroupBy(x => x.GroupID).Select(x => x.First());
the above query will give you the result.
This is your solution:
var myData = models.GroupBy(model => model.GroupId)
.Select(group => group.OrderByDescending(model => model.Id).First());
Or you could also do this:
var myData = models.GroupBy(model => model.GroupId)
.Select(group => group.First(model => model.Id == group.Max(model1 => model1.Id)));
For fun, here's a fiddle.
You can try to use GroupBy.
var q = modelList.GroupBy(x => x.GroupID, x => x,
(key, g) => new {
GroupID = key,
Id = g.Max(c => c.ID)
});
This should group all your elements by GroupId and select Max ID in one of that groups.
Try this code:
List<MyModel> modelList = new List<MyModel>();
modelList.Add(new MyModel());
modelList.Add(new MyModel());
modelList.Add(new MyModel());
modelList.Add(new MyModel());
modelList[0].ID = 1; modelList[0].GroupID = 5;
modelList[1].ID = 2; modelList[1].GroupID = 5;
modelList[2].ID = 3; modelList[2].GroupID = 6;
modelList[3].ID = 4; modelList[3].GroupID = 6;
var list = from ml in modelList group ml by ml.ID into r select new { ID = r.Key, MaxGroupID = r.Max() };
this might help you
modelList.GroupBy(model => model.GroupId, g => g.Id).Select(item => item.Max())
var newModelList = modelList.GroupBy(ml => ml.GroupID)
.Select(g => new MyModel
{
ID = g.OrderByDescending(x => x.ID).First().ID,
GroupID = g.Key
}).ToList();
Details
1) GroupBy then Select to get distinct items over GroupID.
2) First() after OrderByDescending to get highest ID.
3) new MyModel in Select is just to be explicit about the projection.