I want to group by a table with Order Id but if one of price is negative don’t group by and brings all rows in output
I use below code but group by all order id
tblResult = tblResult.AsEnumerable().GroupBy(r => new { orderId = r["OrderID"] }).Select(g =>
{
var row = tblResult.NewRow();
row["Order ID"] = g.Key.orderId;
row["Price"] = g.Sum(r => float.Parse(r.Field<string>("Price"))).ToString();
return row;
}).CopyToDataTable();
You can create your condition in grouping, the tricky part is the result would be a list for those with negative prices and single item for those without it. if we also make single items as list then SelectMany() shoud do what you want:
var result = list.GroupBy(x => x.Id)
.SelectMany(g => g.Any(x => x.Price < 0)?
g.ToList():
new List<Order> { new Order { Id = g.Key, Price = g.Sum(grp => grp.Price)}});
LIVE DEMO
Related
I search more on this site for "get 4 top item from each group", but there are many topic about get first item from each group like this
var rr = db.Products
.GroupBy(x => x.ProductSubTypeCategoryId, (key, g) => g.OrderBy(e => e.PersianName)
.Take(4).ToList());
or
var rr = db.Products
.GroupBy(x => x.ProductSubTypeCategoryId).Select(g => new { pname = g.Key, count = g.Count() });
but return only first item from each group. How can I change the code to get 4 items from each group?
Try this:
var rr = db.Products.GroupBy(x => x.ProductSubTypeCategoryId).Select(g => new { GroupName = g.Key, Items = g.Take(4).ToList() });
This should give you an anonymous object with a GroupName property that returns the ProductSubTypeCategoryId and an Items property that returns a list of up to 4 items for each group.
Try something like this with SelectMany()
var rr = db.Products
.GroupBy(x => x.ProductSubTypeCategoryId)
.SelectMany(g => g.OrderBy(e => e.PersianName).Take(4))
.ToList();
Using the following linq code, how can I add dense_rank to my results? If that's too slow or complicated, how about just the rank window function?
var x = tableQueryable
.Where(where condition)
.GroupBy(cust=> new { fieldOne = cust.fieldOne ?? string.Empty, fieldTwo = cust.fieldTwo ?? string.Empty})
.Where(g=>g.Count()>1)
.ToList()
.SelectMany(g => g.Select(cust => new {
cust.fieldOne
, cust.fieldTwo
, cust.fieldThree
}));
This does a dense_rank(). Change the GroupBy and the Order according to your need :)
Basically, dense_rank is numbering the ordered groups of a query so:
var DenseRanked = data.Where(item => item.Field2 == 1)
//Grouping the data by the wanted key
.GroupBy(item => new { item.Field1, item.Field3, item.Field4 })
.Where(#group => #group.Any())
// Now that I have the groups I decide how to arrange the order of the groups
.OrderBy(#group => #group.Key.Field1 ?? string.Empty)
.ThenBy(#group => #group.Key.Field3 ?? string.Empty)
.ThenBy(#group => #group.Key.Field4 ?? string.Empty)
// Because linq to entities does not support the following select overloads I'll cast it to an IEnumerable - notice that any data that i don't want was already filtered out before
.AsEnumerable()
// Using this overload of the select I have an index input parameter. Because my scope of work is the groups then it is the ranking of the group. The index starts from 0 so I do the ++ first.
.Select((#group , i) => new
{
Items = #group,
Rank = ++i
})
// I'm seeking the individual items and not the groups so I use select many to retrieve them. This overload gives me both the item and the groups - so I can get the Rank field created above
.SelectMany(v => v.Items, (s, i) => new
{
Item = i,
DenseRank = s.Rank
}).ToList();
Another way is as specified by Manoj's answer in this question - But I prefer it less because of the selecting twice from the table.
So if I understand this correctly, the dense rank is the index of the group it would be when the groups are ordered.
var query = db.SomeTable
.GroupBy(x => new { x.Your, x.Key })
.OrderBy(g => g.Key.Your).ThenBy(g => g.Key.Key)
.AsEnumerable()
.Select((g, i) => new { g, i })
.SelectMany(x =>
x.g.Select(y => new
{
y.Your,
y.Columns,
y.And,
y.Key,
DenseRank = x.i,
}
);
var denseRanks = myDb.tblTestReaderCourseGrades
.GroupBy(x => new { x.Grade })
.OrderByDescending(g => g.Key.Grade)
.AsEnumerable()
.Select((g, i) => new { g, i })
.SelectMany(x =>
x.g.Select(y => new
{
y.Serial,
Rank = x.i + 1,
}
));
var storeIds = repository.Get<Store>()
.Select(s => s.Id)
.ToList();
var storeReceipts = repository.Get<Receipt>()
.Where(r => DbFunctions.TruncateTime(r.LogDate) == today)
.GroupBy(r => r.StoreId)
.Select(g => new { Id = g.Key, Sales = g.Sum(r => r.TotalPrice) })
.GroupJoin(storeIds, x => x.Id, s => s, (x, s) => x ?? new { Id = s, Sales = 0 });
Basically I want the GroupJoin to add an entry to the sequence for any Store that doesn't have Receipt records.
My syntax above with the ?? doesn't compile (even if it did I am not sure its correct).
If you want to join the two tables, you may want to try this.
var storeSales = from s in repository.Get<Store>()
join r in repository.Get<Receipt>() on s.Id equals r.StoreId into g
select new {
StoreId = s.Id,
Sales = g.Sum(x => (decimal?)x.TotalPrice) ?? 0
};
It selects from the Stores first, so that you will get an entry for each store. It will next join the Receipts by matching store id into a group g that joins the two.
That allows the selection of your output shape, one item per store. In this case, the Id of the store as StoreId, and the sum of the TotalPrice values for each receipt as the Sales are selected.
If there were no receipts for a store, this sum will end up being 0.
I need to index the item list with its position after grouping
var result = from i in items
group i by i.name into g
select new { groupname = g.Key,
index = //need to get the index of the item
};
How to get the item index of a list using linq/lambda?
I'm not 100% sure what you're trying to achieve, but I would definitely advice to use methods instead of syntax-based query.
var results = items.GroupBy(x => x.name)
.Select((g, i) => new { product = g.Key, index = i });
Or if you'd like to get indexes from source lift for all items within every group:
var results = items.Select((x, i) => new { x, i })
.GroupBy(x => x.x.name)
.Select(g => new {
product = g.Key,
indexes = g.Select(x => x.i).ToList()
});
var idx = 0;
var result = from i in items
group i by i.name into g
select new { product = g.Key,
index = idx++
};
I want to write this simple query with Linq:
select issuercode,securitycode,dataprocessingflag,COUNT(issuercode) as cnt
from cmr_invhdr
where ProcessedLike <> 'STMNT ONLY'
group by issuercode,securitycode,dataprocessingflag
order by Issuercode
I've tried the following code but I get this error( DbExpressionBinding requires an input expression with a collection ResultType.
Parameter name: input) :
var lstCMRInvHdrNips = (from r in e.CMR_INVHDR
where r.ProcessedLike != "STMNT ONLY"
select new {
r.IssuerCode,
r.SecurityCode,
CountofIssuerCode = r.IssuerCode.Count(),
r.DataProcessingFlag
}
).GroupBy(x =>
new {
x.IssuerCode,
x.SecurityCode,
x.DataProcessingFlag,
x.CountofIssuerCode
}
).OrderBy(x => x.Key.IssuerCode).ToList();
Is there any sense to count issuercode while grouping by this field at once? As when groupped by a field, it's COUNT will always be 1.
Probably you should not group by issuercode and count it after the GroupBy in a separate Select statement:
var result = e.CMR_INVHDR
.Where(r => r.ProcessedLike != "STMNT ONLY")
.GroupBy(r => new { r.SecurityCode, r.DataProcessingFlag })
.Select(r => new
{
Value = r.Key,
IssuerCodesCount = r.GroupBy(g => g.IssuerCode).Count()
})
.ToList();