How can I get the Nth row using Linq? both columns are text so I cant use min/max
var nthItem = items.Skip(n).First();
An alternative (.Net 3.5 and later) is to use ElementAtOrDefault.
var nthItem = items.ElementAtOrDefault(n-1);
The method's index is zero-based, so if you want the third element, you pass 2 for the index.
You can use skip and take.
var result = myData.OrderBy(<your order by>).Skip(5).Take(1);
var nthItem = items.Skip(n-1).FirstOrDefault();
you can use order by with skip
var nthItem = items.OrderByDescending(<your order by>).skip(n-1).FirstOrDefault();
Related
I have an array of string
var searchString = new string[] {"1:PS", "2:PS"};
and a large result string eg;
var largeString = "D9876646|10|1:PS^CD9876647100|11|2:PS"
how do I check if any of the options in searchString exist in the largeString?
I know it can be done via loop quite easily but I am looking for an other way around since I need to append the following as search clause in linq query.
You can use LINQ for it with a simple Any() call, like this:
var hasAny = searchString.Any(sub => largeString.Contains(sub));
However, this is as slow as a foreach loop. You can find the answer faster with a regex constructed from searchString:
var regex = string.Join("|", searchString.Select(Regex.Escape));
var hasAny = Regex.IsMatch(largeString, regex);
Depending on the nature of your LINQ provider (assuming it isn't LINQ to Objects), you may want to add individual tests for each member of searchString. The best way to do this is probably using PredicateBuilder
var sq = PredicateBuilder.New<dbType>();
foreach (var s in searchString)
sq = sq.Or(r => r.largeString.Contains(s));
q = q.Where(sq);
I'm trying to add the property
var range = sheet.Cells ["A6: R6"];
range.AutoFilter = true;
It does not work, apply the filter to all columns of the merge. How to solve? thanks
Remove the space in your cell range string. In other words:
var range = sheet.Cells ["A6: R6"];
Should be:
var range = sheet.Cells ["A6:R6"];
That will definitely trip it up. If that doesnt fix it post more of your code.
I'm using the LinqToExcel library. Working great so far, except that I need to start the query at a specific row. This is because the excel spreadsheet from the client uses some images and "header" information at the top of the excel file before the data actually starts.
The data itself will be simple to read and is fairly generic, I just need to know how to tell the ExcelQueryFactory to start at a specific row.
I am aware of the WorksheetRange<Company>("B3", "G10") option, but I don't want to specify an ending row, just where to start reading the file.
Using the latest v. of LinqToExcel with C#
I just tried this code and it seemed to work just fine:
var book = new LinqToExcel.ExcelQueryFactory(#"E:\Temporary\Book1.xlsx");
var query =
from row in book.WorksheetRange("A4", "B16384")
select new
{
Name = row["Name"].Cast<string>(),
Age = row["Age"].Cast<int>(),
};
I only got back the rows with data.
I suppose that you already solved this, but maybe for others - looks like you can use
var excel = new ExcelQueryFactory(path);
var allRows = excel.WorksheetNoHeader();
//start from 3rd row (zero-based indexing), length = allRows.Count() or computed range of rows you want
for (int i = 2; i < length; i++)
{
RowNoHeader row = allRows.ElementAtOrDefault(i);
//process the row - access columns as you want - also zero-based indexing
}
Not as simple as specifying some Range("B3", ...), but also the way.
Hope this helps at least somebody ;)
I had tried this, works fine for my scenario.
//get the sheets info
var faceWrksheet = excel.Worksheet(facemechSheetName);
// get the total rows count.
int _faceMechRows = faceWrksheet.Count();
// append with End Range.
var faceMechResult = excel.WorksheetRange<ExcelFaceMech>("A5", "AS" + _faceMechRows.ToString(), SheetName).
Where(i => i.WorkOrder != null).Select(x => x).ToList();
Have you tried WorksheetRange<Company>("B3", "G")
Unforunatly, at this moment and iteration in the LinqToExcel framework, there does not appear to be any way to do this.
To get around this we are requiring the client to have the data to be uploaded in it's own "sheet" within the excel document. The header row at the first row and the data under it. If they want any "meta data" they will need to include this in another sheet. Below is an example from the LinqToExcel documentation on how to query off a specific sheet.
var excel = new ExcelQueryFactory("excelFileName");
var oldCompanies = from c in repo.Worksheet<Company>("US Companies") //worksheet name = 'US Companies'
where c.LaunchDate < new DateTime(1900, 0, 0)
select c;
I want to extract part of a collection to another collection.
I can easily do the same using a for loop, but my linq query is not working for the same.
I am a neophyte in Linq, so please help me correcting the query (if possible with explanation / beginners tutorial link)
Legacy way of doing :
Collection<string> testColl1 = new Collection<string> {"t1", "t2", "t3", "t4"};
Collection<string> testColl2 = new Collection<string>();
for (int i = 0; i < newLength; i++)
{
testColl2.Add(testColl1[i]);
}
Where testColl1 is the source & testColl2 is the desired truncated collection of count = newLength.
I have used the following linq queries, but none of them are working ...
var result = from t in testColl1 where t.Count() <= newLength select t;
var res = testColl1.Where(t => t.Count() <= newLength);
Use Enumerable.Take:
var testColl2 = testColl1.Take(newLength).ToList();
Note that there's a semantic difference between your for loop and the version using Take. The for loop will throw with IndexOutOfRangeException exception if there are less than newLength items in testColl1, whereas the Take version will silently ignore this fact and just return as many items up to newLength items.
The correct way is by using Take:
var result = testColl1.Take(newLength);
An equivalent way using Where is:
var result = testColl1.Where((i, item) => i < newLength);
These expressions will produce an IEnumerable, so you might also want to attach a .ToList() or .ToArray() at the end.
Both ways return one less item than your original implementation does because it is more natural (e.g. if newLength == 0 no items should be returned).
You could convert to for loop to something like this:
testColl1.Take(newLength)
Use Take:
var result = testColl1.Take(newLength);
This extension method returns the first N elements from the collection where N is the parameter you pass, in this case newLength.
Can anybody tell me how I would get the records in the first statement that are not in the second statement (see below)?
from or in TblOrganisations
where or.OrgType == 2
select or.PkOrgID
Second query:
from o in TblOrganisations
join m in LuMetricSites
on o.PkOrgID equals m.FkSiteID
orderby m.SiteOrder
select o.PkOrgID
If you only need the IDs then Except should do the trick:
var inFirstButNotInSecond = first.Except(second);
Note that Except treats the two sequences as sets. This means that any duplicate elements in first won't be included in the results. I suspect that this won't be a problem since the name PkOrgID suggests a unique ID of some kind.
(See the documentation for Enumerable.Except and Queryable.Except for more info.)
Do you need the whole records, or just the IDs? The IDs are easy...
var ids = firstQuery.Except(secondQuery);
EDIT: Okay, if you can't do that, you'll need something like:
var secondQuery = ...; // As you've already got it
var query = from or in TblOrganisations
where or.OrgType == 2
where !secondQuery.Contains(or.PkOrgID)
select ...;
Check the SQL it produces, but I think it should do the right thing. Note that there's no point in performing any ordering in the second query - or even the join against TblOrganisations. In other words, you could use:
var query = from or in TblOrganisations
where or.OrgType == 2
where !LuMetricSites.Select(m => m.FkSiteID).Contains(or.PkOrgID)
select ...;
Use Except:
var filtered = first.Except(second);