Why is my delimiter not appearing in the final output? It's initialized to be a comma, but I only get ~5 white spaces between each attribute using:
SELECT [article_id]
, dbo.GROUP_CONCAT(0, t.tag_name, ',') AS col
FROM [AdventureWorks].[dbo].[ARTICLE_TAG_XREF] atx
JOIN [AdventureWorks].[dbo].[TAGS] t ON t.tag_id = atx.tag_id
GROUP BY article_id
The bit for DISTINCT works fine, but it operates within the Accumulate scope...
Output:
article_id | col
-------------------------------------------------
1 | a a b c
Update: The excess space between values is because the column as defined as NCHAR(10), so 10 characters would appear in the output. Silly mistake on my part...
Solution
With Martin Smith's help about working with the Write(BinaryWriter w) method, this update works for me:
public void Write(BinaryWriter w)
{
w.Write(list.Count);
for (int i = 0; i < list.Count; i++ )
{
if (i < list.Count - 1)
{
w.Write(list[i].ToString() + delimiter);
}
else
{
w.Write(list[i].ToString());
}
}
}
The Question:
Why does the above solve my problem? And why wouldn't it let me use more than one w.write call inside the FOR loop?
C# Code:
using System;
using System.Data;
using System.Data.SqlClient;
using System.Data.SqlTypes;
using Microsoft.SqlServer.Server;
using System.Xml.Serialization;
using System.Xml;
using System.IO;
using System.Collections;
using System.Text;
[Serializable]
[SqlUserDefinedAggregate(Format.UserDefined, MaxByteSize = 8000)]
public struct GROUP_CONCAT : IBinarySerialize
{
ArrayList list;
string delimiter;
public void Init()
{
list = new ArrayList();
delimiter = ",";
}
public void Accumulate(SqlBoolean isDistinct, SqlString Value, SqlString separator)
{
delimiter = (separator.IsNull) ? "," : separator.Value ;
if (!Value.IsNull)
{
if (isDistinct)
{
if (!list.Contains(Value.Value))
{
list.Add(Value.Value);
}
}
else
{
list.Add(Value.Value);
}
}
}
public void Merge(GROUP_CONCAT Group)
{
list.AddRange(Group.list);
}
public SqlString Terminate()
{
string[] strings = new string[list.Count];
for (int i = 0; i < list.Count; i++)
{
strings[i] = list[i].ToString();
}
return new SqlString(string.Join(delimiter, strings));
}
#region IBinarySerialize Members
public void Read(BinaryReader r)
{
int itemCount = r.ReadInt32();
list = new ArrayList(itemCount);
for (int i = 0; i < itemCount; i++)
{
this.list.Add(r.ReadString());
}
}
public void Write(BinaryWriter w)
{
w.Write(list.Count);
foreach (string s in list)
{
w.Write(s);
}
}
#endregion
}
The problem here is that you do not serialize delimiter. Add:
w.Write(delimiter)
as a first line in your Write method and
delimiter = r.ReadString();
as a first line in your Read method.
Regarding your questions to suggested work-around:
Why does the above solve my problem?
It does not. It merely worked with your test scenario.
And why wouldn't it let me use more than one w.write call inside the FOR loop?
Write method needs to be compatible with Read method. If you write two strings and read only one then it is not going to work. The idea here is that your object may be removed from the memory and then loaded. This is what Write and Read are supposed to do. In your case - this indeed was happening and you were not able to keep the object value.
The answer given by #agsamek is correct but not complete. The query processor may instantiate multiple aggregators, e.g. for parallel computations, and the one that will eventually hold all data after successive calls of Merge() may be assigned an empty recordset, i.e. its Accumulate() method may be never called:
var concat1 = new GROUP_CONCAT();
concat1.Init();
results = getPartialResults(1); // no records returned
foreach (var result in results)
concat1.Accumulate(result[0], delimiter); // never called
...
var concat2 = new GROUP_CONCAT();
concat2.Init();
results = getPartialResults(2);
foreach (var result in results)
concat2.Accumulate(result[0], delimiter);
...
concat1.Merge(concat2);
...
result = concat1.Terminate();
In this scenario, concat1's private field delimiter used in Terminate() remains what it is by default in Init() but not what you pass in SQL. Luckily or not, your test SQL uses the same delimiter value as in Init(), so you can't reveal the difference.
I'm not sure if this is a bug or if it has been fixed in later versions (I stumbled on it in SQL Server 2008 R2). My workaround was to make use of the other group that is passed in Merge():
public void Merge(GROUP_CONCAT Group)
{
if (Group.list.Count != 0) // Group's Accumulate() has been called at least once
{
if (list.Count == 0) // this Accumulate() has not been called
delimiter = Group.delimiter;
list.AddRange(Group.list);
}
}
P.S. I would use StringBuilder instead of ArrayList.
Related
I have this permutation code working perfectly but it does not generate the code fast enough, I need help with optimizing the code to run faster, please it is important that the result remains the same, I have seen other algorithms but they don't into consideration the output length and same character reputation which are all valid output. if I can have this converted into a for loop with 28 characters of alphanumeric, that would be awesome. below is the current code I am looking to optimize.
namespace CSharpPermutations
{
public interface IPermutable<T>
{
ISet<T> GetRange();
}
public class Digits : IPermutable<int>
{
public ISet<int> GetRange()
{
ISet<int> set = new HashSet<int>();
for (int i = 0; i < 10; ++i)
set.Add(i);
return set;
}
}
public class AlphaNumeric : IPermutable<char>
{
public ISet<char> GetRange()
{
ISet<char> set = new HashSet<char>();
set.Add('0');
set.Add('1');
set.Add('2');
set.Add('3');
set.Add('4');
set.Add('5');
set.Add('6');
set.Add('7');
set.Add('8');
set.Add('9');
set.Add('a');
set.Add('b');
return set;
}
}
public class PermutationGenerator<T,P> : IEnumerable<string>
where P : IPermutable<T>, new()
{
public PermutationGenerator(int number)
{
this.number = number;
this.range = new P().GetRange();
}
public IEnumerator<string> GetEnumerator()
{
foreach (var item in Permutations(0,0))
{
yield return item.ToString();
}
}
IEnumerator IEnumerable.GetEnumerator()
{
foreach (var item in Permutations(0,0))
{
yield return item;
}
}
private IEnumerable<StringBuilder> Permutations(int n, int k)
{
if (n == number)
yield return new StringBuilder();
foreach (var element in range.Skip(k))
{
foreach (var result in Permutations(n + 1, k + 1))
{
yield return new StringBuilder().Append(element).Append(result);
}
}
}
private int number;
private ISet<T> range;
}
class MainClass
{
public static void Main(string[] args)
{
foreach (var element in new PermutationGenerator<char, AlphaNumeric>(2))
{
Console.WriteLine(element);
}
}
}
}
Thanks for your effort in advance.
What you're outputting there is the cartesian product of two sets; the first set is the characters "0123456789ab" and the second set is the characters "123456789ab".
Eric Lippert wrote a well-known article demonstrating how to use Linq to solve this.
We can apply this to your problem like so:
using System;
using System.Collections.Generic;
using System.Linq;
namespace Demo;
static class Program
{
static void Main(string[] args)
{
char[][] source = new char[2][];
source[0] = "0123456789ab".ToCharArray();
source[1] = "0123456789ab".ToCharArray();
foreach (var perm in Combine(source))
{
Console.WriteLine(string.Concat(perm));
}
}
public static IEnumerable<IEnumerable<T>> Combine<T>(IEnumerable<IEnumerable<T>> sequences)
{
IEnumerable<IEnumerable<T>> emptyProduct = new[] { Enumerable.Empty<T>() };
return sequences.Aggregate(
emptyProduct,
(accumulator, sequence) =>
from accseq in accumulator
from item in sequence
select accseq.Concat(new[] { item }));
}
}
You can extend this to 28 characters by modifying the source data:
source[0] = "0123456789abcdefghijklmnopqr".ToCharArray();
source[1] = "0123456789abcdefghijklmnopqr".ToCharArray();
If you want to know how this works, read Eric Lipper's excellent article, which I linked above.
Consider
foreach (var result in Permutations(n + 1, k + 1))
{
yield return new StringBuilder().Append(element).Append(result);
}
Permutations is a recursive function that implements an iterator. So each time the .MoveNext() method is will advance one step of the loop, that will call MoveNext() in turn etc, resulting in N calls to MoveNext(), new StringBuilder, Append() etc. This is quite inefficient.
A can also not see that stringBuilder gives any advantage here. It is a benefit if you concatenate many strings, but as far as I can see you only add two strings together.
The first thing you should do is add code to measure the performance, or even better, use a profiler. That way you can tell if any changes actually improves the situation or not.
The second change I would try would be to try rewrite the recursion to an iterative implementation. This probably means that you need to keep track of an explicit stack of the numbers to process. Or if this is to difficult, stop using iterator blocks and let the recursive method take a list that it adds results to.
Whenever I run this code, it returns one character. I've tried various things, and at most it returns 5 or so lines, each containing one character. I'm trying to find each folder in the "Users" folder, and make my code list them, any help would be appreciated.
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;
namespace ConsoleApp3
{
class Program
{
static void Main(string[] args)
{
//Search for directories and foreach, try to start discord
try
{
var Bruhm = new List<string>();
Bruhm.Add(Directory.GetDirectories(#"C:\Users\").ToString());
int y = 0;
foreach (string x in Bruhm) {
Console.WriteLine(x[y]);
y = y+1;
}
}
catch(Exception e)
{
Console.WriteLine(e);
System.Threading.Thread.Sleep(-1);
}
System.Threading.Thread.Sleep(-1);
}
}
}
The first mistake you are making is;
Bruhm.Add(Directory.GetDirectories(#"C:\Users\").ToString());
will add only one string, which is System.String[] to your list.
The second mistake is, x[y] will print only one character, which is the character at y index inside the string x.
Change the Add() to AddRange(), and do not call ToString() on your list.
Try this:
var Bruhm = new List<string>();
Bruhm.AddRange(Directory.GetDirectories(#"C:\Users\"));
foreach (string x in Bruhm)
{
Console.WriteLine(x);
}
It's quite simple. You're doing error with this: Directory.GetDirectories(#"C:\Users\").ToString()
Instead try this:
var Bruhm = Directory.GetDirectories(#"C:\Users\");
foreach(var subdir in Bruhm)
Console.WriteLine(subDir);
You are converting a list into a string and printing an index of it and it makes wrong result. You can extract the folder name using this code. "C:\Users\" has removed from the folder's path to provide folders' name not path.
var path = #"C:\Users\";
var Bruhm = Directory.GetDirectories(path).Select(x => x.Substring(path.Length));
foreach (string x in Bruhm)
{
Console.WriteLine(x);
}
I'm new to Roslyn. I'm writing a code fix provider that transforms foreach blocks that iterate through the results of a Select, e.g.
foreach (var item in new int[0].Select(i => i.ToString()))
{
...
}
to
foreach (int i in new int[0])
{
var item = i.ToString();
...
}
To do this, I need to insert a statement at the beginning of the BlockSyntax inside the ForEachStatementSyntax that represents the foreach block. Here is my code for that:
var blockStatement = forEach.Statement as BlockSyntax;
if (blockStatement == null)
{
return document;
}
forEach = forEach.WithStatement(
blockStatment.WithStatements(
blockStatement.Statements.Insert(0, selectorStatement));
Unfortunately, doing that results in the whitespace being off:
foreach (int i in new int[0])
{
var item = i.ToString();
...
}
I Googled solutions for this. I came across this answer, which recommended using either Formatter.Format or SyntaxNode.NormalizeWhitespace.
I can't use Formatter.Format because that takes a Workspace parameter, and it looks I don't have access to a Workspace per Roslyn: Current Workspace in Diagnostic with code fix project.
I tried using NormalizeWhitespace() on the syntax root of the document, but that invasively formatted other code not related to the fix. I tried using it on just the ForEachStatementSyntax associated with the foreach block, and then calling syntaxRoot = syntaxRoot.ReplaceNode(oldForEach, newForEach), but that results in the entire foreach block not being properly indented.
namespace ConsoleApp1
{
class Program
{
static void Main(string[] args)
{
var array = new int[0];
int length = array.Length;
foreach (int i in array)
{
string item = i.ToString();
} }
}
}
So is it possible to simply insert the statement with the correct indentation in the first place, without having to format other code?
Thanks.
You can add the Formatter Annotation to the nodes that you want the formatter to run on using WithAdditionalAnnotations
blockStatement.Statements.Insert(0, selectorStatement.WithAdditionalAnnotations(Formatter.Annotation))
I've got a work around for this issue, but I'm trying to figure out why it works . Basically, I'm looping through a list of structs using foreach. If I include a LINQ statement that references the current struct before I call a method of the struct, the method is unable to modify the members of the struct. This happens regardless of whether the LINQ statement is even called. I was able to work around this by assigning the value I was looking for to a variable and using that in the LINQ, but I would like to know what is causing this. Here's an example I created.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace WeirdnessExample
{
public struct RawData
{
private int id;
public int ID
{
get{ return id;}
set { id = value; }
}
public void AssignID(int newID)
{
id = newID;
}
}
public class ProcessedData
{
public int ID { get; set; }
}
class Program
{
static void Main(string[] args)
{
List<ProcessedData> processedRecords = new List<ProcessedData>();
processedRecords.Add(new ProcessedData()
{
ID = 1
});
List<RawData> rawRecords = new List<RawData>();
rawRecords.Add(new RawData()
{
ID = 2
});
int i = 0;
foreach (RawData rawRec in rawRecords)
{
int id = rawRec.ID;
if (i < 0 || i > 20)
{
List<ProcessedData> matchingRecs = processedRecords.FindAll(mr => mr.ID == rawRec.ID);
}
Console.Write(String.Format("With LINQ: ID Before Assignment = {0}, ", rawRec.ID)); //2
rawRec.AssignID(id + 8);
Console.WriteLine(String.Format("ID After Assignment = {0}", rawRec.ID)); //2
i++;
}
rawRecords = new List<RawData>();
rawRecords.Add(new RawData()
{
ID = 2
});
i = 0;
foreach (RawData rawRec in rawRecords)
{
int id = rawRec.ID;
if (i < 0)
{
List<ProcessedData> matchingRecs = processedRecords.FindAll(mr => mr.ID == id);
}
Console.Write(String.Format("With LINQ: ID Before Assignment = {0}, ", rawRec.ID)); //2
rawRec.AssignID(id + 8);
Console.WriteLine(String.Format("ID After Assignment = {0}", rawRec.ID)); //10
i++;
}
Console.ReadLine();
}
}
}
Okay, I've managed to reproduce this with a rather simpler test program, as shown below, and I now understand it. Admittedly understanding it doesn't make me feel any less nauseous, but hey... Explanation after code.
using System;
using System.Collections.Generic;
struct MutableStruct
{
public int Value { get; set; }
public void AssignValue(int newValue)
{
Value = newValue;
}
}
class Test
{
static void Main()
{
var list = new List<MutableStruct>()
{
new MutableStruct { Value = 10 }
};
Console.WriteLine("Without loop variable capture");
foreach (MutableStruct item in list)
{
Console.WriteLine("Before: {0}", item.Value); // 10
item.AssignValue(30);
Console.WriteLine("After: {0}", item.Value); // 30
}
// Reset...
list[0] = new MutableStruct { Value = 10 };
Console.WriteLine("With loop variable capture");
foreach (MutableStruct item in list)
{
Action capture = () => Console.WriteLine(item.Value);
Console.WriteLine("Before: {0}", item.Value); // 10
item.AssignValue(30);
Console.WriteLine("After: {0}", item.Value); // Still 10!
}
}
}
The difference between the two loops is that in the second one, the loop variable is captured by a lambda expression. The second loop is effectively turned into something like this:
// Nested class, would actually have an unspeakable name
class CaptureHelper
{
public MutableStruct item;
public void Execute()
{
Console.WriteLine(item.Value);
}
}
...
// Second loop in main method
foreach (MutableStruct item in list)
{
CaptureHelper helper = new CaptureHelper();
helper.item = item;
Action capture = helper.Execute;
MutableStruct tmp = helper.item;
Console.WriteLine("Before: {0}", tmp.Value);
tmp = helper.item;
tmp.AssignValue(30);
tmp = helper.item;
Console.WriteLine("After: {0}", tmp.Value);
}
Now of course each time we copy the variable out of helper we get a fresh copy of the struct. This should normally be fine - the iteration variable is read-only, so we'd expect it not to change. However, you have a method which changes the contents of the struct, causing the unexpected behaviour.
Note that if you tried to change the property, you'd get a compile-time error:
Test.cs(37,13): error CS1654: Cannot modify members of 'item' because it is a
'foreach iteration variable'
Lessons:
Mutable structs are evil
Structs which are mutated by methods are doubly evil
Mutating a struct via a method call on an iteration variable which has been captured is triply evil to the extent of breakage
It's not 100% clear to me whether the C# compiler is behaving as per the spec here. I suspect it is. Even if it's not, I wouldn't want to suggest the team should put any effort into fixing it. Code like this is just begging to be broken in subtle ways.
Ok. We definitely have an issues here but I suspect that this issue not with closures per se but with foreach implementation instead.
C# 4.0 specification stated (8.8.4 The foreach statement) that "the iteration variable corresponds to a read-only local variable with a scope that extends over the embedded statement". That's why we can't change loop variable or increment it's property (as Jon already stated):
struct Mutable
{
public int X {get; set;}
public void ChangeX(int x) { X = x; }
}
var mutables = new List<Mutable>{new Mutable{ X = 1 }};
foreach(var item in mutables)
{
// Illegal!
item = new Mutable();
// Illegal as well!
item.X++;
}
In this regard read-only loop variables behave almost exactly the same as any readonly field (in terms of accessing this variable outside of the constructor):
We can't change readonly field outside of the constructor
We can't change property of the read-only field of value type
We're treating readonly fields as values that leads to using a temporary copy every time we accessing readonly field of value type.
.
class MutableReadonly
{
public readonly Mutable M = new Mutable {X = 1};
}
// Somewhere in the code
var mr = new MutableReadonly();
// Illegal!
mr.M = new Mutable();
// Illegal as well!
mr.M.X++;
// Legal but lead to undesired behavior
// becaues mr.M.X remains unchanged!
mr.M.ChangeX(10);
There is a plenty of issues related to mutable value types and one of them related to the last behavior: changing readonly struct via mutator method (like ChangeX) lead to obscure behavior because we'll modify a copy but not an readonly object itself:
mr.M.ChangeX(10);
Is equivalent to:
var tmp = mr.M;
tmp.ChangeX(10);
If loop variable treated by the C# compiler as a read-only local variable, than its seems reasonable to expect the same behavior for them as for read-only fields.
Right now loop variable in the simple loop (without any closures) behaves almost the same as a read-only field except copying it for every access. But if code changes and closure comes to play, loop variable starts behaving like pure read-only variable:
var mutables = new List<Mutable> { new Mutable { X = 1 } };
foreach (var m in mutables)
{
Console.WriteLine("Before change: {0}", m.X); // X = 1
// We'll change loop variable directly without temporary variable
m.ChangeX(10);
Console.WriteLine("After change: {0}", m.X); // X = 10
}
foreach (var m in mutables)
{
// We start treating m as a pure read-only variable!
Action a = () => Console.WriteLine(m.X));
Console.WriteLine("Before change: {0}", m.X); // X = 1
// We'll change a COPY instead of a m variable!
m.ChangeX(10);
Console.WriteLine("After change: {0}", m.X); // X = 1
}
Unfortunately I can't find strict rules how read-only local variables should behave but its clear that this behavior is different based on loop body: we're not copying to locals for every access in simple loop, but we DO this if the loop body closes over loop variable.
We all know that Closing over loop variable considered harmful and that loop implementation was changed in the C# 5.0. Simple way to fix that old issue in pre C# 5.0 era was introducing local variable, but interesting that introducing local variable in this our case will change behavior as well:
foreach (var mLoop in mutables)
{
// Introducing local variable!
var m = mLoop;
// We're capturing local variable instead of loop variable
Action a = () => Console.WriteLine(m.X));
Console.WriteLine("Before change: {0}", m.X); // X = 1
// We'll roll back this behavior and will change
// value type directly in the closure without making a copy!
m.ChangeX(10); // X = 10 !!
Console.WriteLine("After change: {0}", m.X); // X = 1
}
Actually this means that C# 5.0 has very subtle breaking change because no one will introduce a local variable any more (and even tools like ReSharper stops warning about it in VS2012 because its not an issue).
I'm OK with both behaviors but inconsistency seems strange.
I suspect this has to do with how lambda expressions are evaluated. See this question and its answer for more details.
Question:
When using lambda expressions or anonymous methods in C#, we have to be wary of the access to modified closure pitfall. For example:
foreach (var s in strings)
{
query = query.Where(i => i.Prop == s); // access to modified closure
Due to the modified closure, the above code will cause all of the Where clauses on the query to be based on the final value of s.
Answer:
This is one of the worst "gotchas" in C#, and we are going to take the breaking change to fix it. In C# 5 the foreach loop variable will be logically inside the body of the loop, and therefore closures will get a fresh copy every time.
Just to accomplish Sergey's post, I wanna to add following example with manual closure, that demonstrates compiler's behavior. Of course compiler might have any other implementation that satisfies readonly requirement of captured within foreach statement variable.
static void Main()
{
var list = new List<MutableStruct>()
{
new MutableStruct { Value = 10 }
};
foreach (MutableStruct item in list)
{
var c = new Closure(item);
Console.WriteLine(c.Item.Value);
Console.WriteLine("Before: {0}", c.Item.Value); // 10
c.Item.AssignValue(30);
Console.WriteLine("After: {0}", c.Item.Value); // Still 10!
}
}
class Closure
{
public Closure(MutableStruct item){
Item = item;
}
//readonly modifier is mandatory
public readonly MutableStruct Item;
public void Foo()
{
Console.WriteLine(Item.Value);
}
}
This might solve your issue. It swaps out foreach for a for and makes the struct immutable.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace WeirdnessExample
{
public struct RawData
{
private readonly int id;
public int ID
{
get{ return id;}
}
public RawData(int newID)
{
id = newID;
}
}
public class ProcessedData
{
private readonly int id;
public int ID
{
get{ return id;}
}
public ProcessedData(int newID)
{
id = newID;
}
}
class Program
{
static void Main(string[] args)
{
List<ProcessedData> processedRecords = new List<ProcessedData>();
processedRecords.Add(new ProcessedData(1));
List<RawData> rawRecords = new List<RawData>();
rawRecords.Add(new RawData(2));
for (int i = 0; i < rawRecords.Count; i++)
{
RawData rawRec = rawRecords[i];
int id = rawRec.ID;
if (i < 0 || i > 20)
{
RawData rawRec2 = rawRec;
List<ProcessedData> matchingRecs = processedRecords.FindAll(mr => mr.ID == rawRec2.ID);
}
Console.Write(String.Format("With LINQ: ID Before Assignment = {0}, ", rawRec.ID)); //2
rawRec = new RawData(rawRec.ID + 8);
Console.WriteLine(String.Format("ID After Assignment = {0}", rawRec.ID)); //2
i++;
}
rawRecords = new List<RawData>();
rawRecords.Add(new RawData(2));
for (int i = 0; i < rawRecords.Count; i++)
{
RawData rawRec = rawRecords[i];
int id = rawRec.ID;
if (i < 0)
{
List<ProcessedData> matchingRecs = processedRecords.FindAll(mr => mr.ID == id);
}
Console.Write(String.Format("With LINQ: ID Before Assignment = {0}, ", rawRec.ID)); //2
rawRec = new RawData(rawRec.ID + 8);
Console.WriteLine(String.Format("ID After Assignment = {0}", rawRec.ID)); //10
i++;
}
Console.ReadLine();
}
}
}
I currently have a log object I'd like to remove objects from, based on a LINQ query. I would like to remove all records in the log if the sum of the versions within a program are greater than 60. Currently I'm pretty confident that this'll work, but it seems kludgy:
for (int index = 0; index < 4; index++)
{
Log.RemoveAll(log =>
(log.Program[index].Version[0].Value +
log.Program[index].Version[1].Value +
log.Program[index].Version[2].Value ) > 60);
}
The Program is an array of 4 values and version has an array of 3 values. Is there a more simple way to do this RemoveAll in LINQ without using the for loop?
Thanks for any help in advance!
EDIT:
Unfortunately the type of variable that Program and Version are based off of (which is a constraint of the framework I'm working in) restricts us such that I cannot access the "Any" member. I however confirmed that tzaman's solution works if you have lists by creating some sample code. I'm restricted to array-like variables (see the commented out areas)
// I'm restricted to Arrays, but if I had lists, this would work.
internal class MyLogCollection
{
List<MyLog> MyListOfZones = new List<MyLog>();
public void TestRemove()
{
// Original Implementation
for (int i = 0; i < 4; i++)
{
MyListOfZones.RemoveAll(log => (log.MyZoneArray[0].MyVersionArray[0].Value +
log.MyZoneArray[0].MyVersionArray[1].Value +
log.MyZoneArray[0].MyVersionArray[2].Value) > 60);
//"Any" method is not available off of intellisense scope on MyZoneArray
}
// Better Implementation (thanks tzaman!)
MyListOfZones.RemoveAll(log => (log.MyZoneArray.Any(prog =>
prog.MyVersionArray.Sum(ver => ver.Value) > 60)));
}
}
internal class MyLog
{
//public MyZone[] MyZoneArray = new MyZone[4];
public List<MyZone> MyZoneArray = new List<MyZone>(4);
}
internal class MyZone
{
//public MyVersion[] MyVersionArray = new MyVersion[3];
public List<MyVersion> MyVersionArray = new List<MyVersion>(3);
}
internal class MyVersion
{
public byte Value { get; set;}
}
Thanks tzaman!
This should do it, I think:
Log.RemoveAll(log =>
log.Program.Any(prog =>
prog.Version.Sum(ver => ver.Value) > 60));
EDIT: Okay, so here's how to add extension methods to get IEnumerables from your indexable "array-like" objects, so that you can use LINQ on them:
static class MyExtensions
{
public static IEnumerable<MyZone> Enumerate(this MyZoneArray zone)
{
for (int i = 0; i < zone.Length; i++)
yield return zone[i];
}
public static IEnumerable<MyVersion> Enumerate(this MyVersionArray version)
{
for (int i = 0; i < version.Length; i++)
yield return version[i]
}
}
I'm assuming the MyZoneArray and MyVersionArray types have a Length field, but if not you could just put in 4 and 3 over there. With these in place, you can now call the Enumerate() function on the collection object to get an IEnumerable version of the collection, with all the associated LINQy goodness attached: log.MyZoneArray.Enumerate().Any( ... )