I have a list of files say prg_3.txt , prg_2.txt , prg_1.txt .
I need to loop over the files and merge the files in order 1,2,3 .
The query i am using is as follows:
var Groups = shortfilenames.GroupBy(s => s.Substring(0, s.IndexOf('_'))).ToList();
The above query would create a group names prg and it will have 3 files.
Now,i need to sort them in the order 1,2,3 i.e fromm their file names.
Here, I am getting grouped results, but i am not sure how to order the elements in each group
Please help..let me know incase of any questions..
Edited :
Will it be good enough ?
var userGroups = shortfilenames.GroupBy(s => s.Substring(0, s.IndexOf('_'))).Select(g=>g.OrderBy(x=>x.Substring(x.IndexOf('_',x.Length-x.IndexOf('_')))));
This should work but probably won't be so efficient:
shortfilenames
.GroupBy(s => s.Substring(0, s.IndexOf('_')))
.Select(
g => g.OrderBy(x => int.Parse(new String(x.Where(char.IsDigit).ToArray()))));
This will not work if your file contains additional digits, here is another solution to fix that, according to your comment this should work with the format you specified:
shortfilenames
.GroupBy(s => s.Substring(0, s.IndexOf('_')))
.Select(g => g.OrderBy(
x =>
{
var index = x.IndexOf('_');
return int.Parse(x.Substring(index + 1, x.LastIndexOf('.') - index));
}));
Since the names kinda match, what's the problem with simply using the OrderBy and giving it the names ?
var v = new string[] {"prg_3.txt","prg_2.txt", "prg_1.txt"};
var sorted = v.OrderBy(name => name);
you get :
prg_1.txt
prg_2.txt
prg_3.txt
If you want to sort inner groupings by file name this should do the trick:
shortfilenames.GroupBy(s => s.Substring(0, s.IndexOf('_'))).Select(g => g.OrderBy(e => e)).ToList();
Related
A sequence of non-empty strings stringList is given, containing only uppercase letters of the Latin alphabet. For all strings starting with the same letter, determine their total length and obtain a sequence of strings of the form "S-C", where S is the total length of all strings from stringList that begin with the character C. Order the resulting sequence in descending order of the numerical values of the sums, and for equal values of the sums, in ascending order of the C character codes.
This question is related to one of my previous questions.
One solution that works is this one:
stringList.GroupBy(x => x[0]).Select(g => $"{g.Sum(x => x.Length)}-{g.Key}");
The problem is that with this given example I don't know where to add the OrderByDescending()/ThenBy() clauses in order to get the correctly sorted list.
Create an intermediate data structure to store needed info and use it for sorting and then building the output:
stringList
.GroupBy(x => x[0])
.Select(g => (Length: g.Sum(x => x.Length), Char: g.Key))
.OrderByDescending(t => t.Length)
.ThenBy(t => t.Char)
.Select(t => $"{t.Length}-{t.Char}");
You're almost there. The cleanest way of doing it would be to make a more complex object with the properties you care about, use those to sort, then keep only what you want in the output. Like:
stringList
.GroupBy(x => x[0])
.Select(g => new {
Len = g.Sum(x => x.Length),
Char = g.Key,
Val = $"{g.Sum(x => x.Length)}-{g.Key}"
})
.OrderByDescending(x => Len)
.ThenBy(x => x.Char)
.Select(x => x.Val);
You can add a Select after the GroupBy to transform the groups into an anonymous object containing the things you want to sort by. Then you can use OrderByDescending and ThenBy to sort. After that, Select the formatted string you want:
stringList.GroupBy(x => x[0]) // assuming all strings are non-empty
.Select(g => new {
LengthSum = g.Sum(x => x.Length),
FirstChar = g.Key
})
.OrderByDescending(x => x.LengthSum)
.ThenBy(x => x.FirstChar)
.Select(x => $"{x.LengthSum}-{x.FirstChar}");
Alternatively, do it in the query syntax with let clauses, which I find more readable:
var query = from str in stringList
group str by str[0] into g
let lengthSum = g.Sum(x => x.Length)
let firstChar = g.Key
orderby lengthSum descending, firstChar
select $"{lengthSum}-{firstChar}";
I have a basic class for an Account (other properties removed for brevity):
public class Account
{
public string Email { get; set; }
}
I have a List<T> of these accounts.
I can remove duplicates based on the e-mail address easily:
var uniques = list.GroupBy(x => x.Email).Select(x => x.First()).ToList();
The list named 'uniques' now contains only one of each account based on e-mail address, any that were duplicates were discarded.
I want to do something a little different and split the list into two.
One list will contain only 'true' unique values, the other list will contain all duplicates.
For example the following list of Account e-mails:
unique#email.com
dupe#email.com
dupe#email.com
Would be split into two lists:
Unique
unique#email.com
Duplicates
dupe#email.com
dupe#email.com
I have been able to achieve this already by creating a list of unique values using the example at the top. I then use .Except() on the original list to get the differences which are the duplicates. Lastly I can loop over each duplicate to 'pop' it out of the unique list and move it to the duplicate list.
Here is a working example on .NET Fiddle
Can I split the list in a more efficient or syntactically sugary way?
I'd be happy to use a third party library if necessary but I'd rather just stick to pure LINQ.
I'm aware of CodeReview but feel the question also fits here.
var groups = list.GroupBy(x => x.Email)
.GroupBy(g => g.Count() == 1 ? 0 : 1)
.OrderBy(g => g.Key)
.Select(g => g.SelectMany(x => x))
.ToList();
groups[0] will be the unique ones and group[1] will be the non-unique ones.
var duplicates = list.GroupBy(x => x) // or x.Property if you are grouping by some property.
.Where(g => g.Count() > 1)
.SelectMany(g => g);
var uniques = list.GroupBy(x => x) // or x.Property if you are grouping by some property.
.Where(g => g.Count() == 1)
.SelectMany(g => g);
Alternatively, once you get one list, you can get the other one using Except:
var uniques = list.Except(duplicates);
// or
var duplicates = list.Except(uniques);
Another way to do it would be to get uniques, and then for duplicates simply get the elements in the original list that aren't in uniques.
IEnumerable<Account> uniques;
IEnumerable<Account> dupes;
dupes = list.Where(d =>
!(uniques = list.GroupBy(x => x.Email)
.Where(g => g.Count() == 1)
.SelectMany(u => u))
.Contains(d));
How can I turn the following statement back to List<DocumentData>
IEnumerable<IGrouping<string, DocumentData>> documents =
documentCollection.Select(d => d).GroupBy(g => g.FileName);
the goal is to get List that should be smaller than documentCollection.
FileName contains duplicates so I want to make sure I don't have duplicate names.
I have also tried the following but it's still providing me with duplicate file names
documentCollection =
documentCollection.GroupBy(g => g.FileName).SelectMany(d => d).ToList();
Each IGrouping<string, DocumentData> is an IEnumerable<DocumentData>, so you could simply call SelectMany to flatten the sequences:
var list = documents.SelectMany(d => d).ToList();
Edit: Per the updated question, it seems like the OP wants to select just the first document for any given filename. This can be achieved by calling First() on each IGrouping<string, DocumentData> instance:
IEnumerable<DocumentData> documents =
documentCollection.GroupBy(g => g.FileName, StringComparer.OrdinalIgnoreCase)
.Select(g => g.First())
.ToList();
You haven't said what T should stand for in List<T> you're looking for, so here are couple the most likely to be desired:
List<DocumentData> - rather pointless as you already have that on documentCollection
var results = documents.SelectMany(g => g).ToList();
List<KeyValuePair<string, List<DocumentData>>
var results =
documents.Select(g => new KeyValuePair(g.Key, g.ToList())).ToList();
List<string> - just the names
var results = documents.Select(g => g.Key).ToList();
List<IGrouping<string, DocumentData>>
var results = documents.ToList();
I've a problem in my C# application... I've some school classes in database for example 8-B, 9-A, 10-C, 11-C and so on .... when I use order by clause to sort them, the string comparison gives results as
10-C
11-C
8-B
9-A
but I want integer sorting on the basis of first integer present in string...
i.e.
8-B
9-A
10-C
11-C
hope you'll understand...
I've tried this but it throws exception
var query = cx.Classes.Select(x=>x.Name)
.OrderBy( x=> new string(x.TakeWhile(char.IsDigit).ToArray()));
Please help me... want ordering on the basis of classes ....
Maybe Split will do?
.OrderBy(x => Convert.ToInt32(x.Split('-')[0]))
.ThenBy(x => x.Split('-')[1])
If the input is well-formed enough, this would do:
var maxLen = cx.Classes.Max(x => x.Name.Length);
var query = cx.Classes.Select(x => x.Name).OrderBy(x => x.PadLeft(maxLen));
You can add 0 as left padding for a specified length as your data for example 6
.OrderBy(x => x.PadLeft(6, '0'))
This is fundamentally the same approach as Andrius's answer, written out more explicitly:
var names = new[] { "10-C", "8-B", "9-A", "11-C" };
var sortedNames =
(from name in names
let parts = name.Split('-')
select new {
fullName = name,
number = Convert.ToInt32(parts[0]),
letter = parts[1]
})
.OrderBy(x => x.number)
.ThenBy(x => x.letter)
.Select(x => x.fullName);
It's my naive assumption that this would be more efficient because the Split is only processed once in the initial select rather than in both OrderBy and ThenBy, but for all I know the extra "layers" of LINQ may outweigh any gains from that.
Here's the scenario:
Given a List of Outputs each associated with an integer based GroupNumber. For each distinct GroupNumber within the List of Outputs starting with the lowest GroupNumber (1). Cycle through that distinct group number set and execute a validation method.
Basically, starting from the lowest to highest group number, validate a set of outputs first before validating a higher groupnumber set.
Thanks,
Matt
There's almost too many ways to solve this:
Here's one for a void Validate method.
source
.GroupBy(x => x.GroupNumber)
.OrderBy(g => g.Key)
.ToList()
.ForEach(g => Validate(g));
Here's one for a bool Validate method.
var results = source
.GroupBy(x => x.GroupNumber)
.OrderBy(g => g.Key)
.Select(g => new
{
GroupNumber = g.Key,
Result = Validate(g),
Items = g.ToList()
})
.ToList();
If you need them as groups:
var qry = source.GroupBy(x=>x.GroupNumber).OrderBy(grp => grp.Key);
foreach(var grp in qry) {
Console.WriteLine(grp.Key);
foreach(var item in grp) {...}
}
If you just need them ordered as though they are grouped:
var qry = source.OrderBy(x=>x.GroupNumber);