I have following code, In which there are list of students , and I want to sort the students first by value column which contains decimal values and after that I want to sort the already sorted list with same column but with different values . Just for understanding , I changed values using foreach loop in the below example.
namespace ConsoleApp1
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Hello World!");
var students = new List<Student>()
{
new Student() { StudentId=1,Name = "Alice", Appd = 10, Value = 3.5 },
new Student() { StudentId=2,Name = "Bob", Appd = 10, Value = 3.7 },
new Student() { StudentId=3,Name = "Raul", Appd = 10, Value = 0.1 },
new Student() { StudentId=4,Name = "Charlie", Appd = 0, Value = 3.6 },
new Student() { StudentId=5,Name = "Dave", Appd = 0, Value = 3.9 },
new Student() { StudentId=6,Name = "Emma", Appd = 0, Value = 3.8 }
};
var orderedFields = students.OrderByDescending(x => x.Value);//5,6,2,4,1,3
foreach ( Student s in orderedFields )
{
s.Value = 120;
}
orderedFields = orderedFields.ThenByDescending(x => x.Value);
var newlist1 = orderedFields.Select(X => X.StudentId).ToList();
}
}
public class Student
{
public int StudentId { get; set; }
public string Name { get; set; }
public int Appd { get; set; }
public double Value { get; set; }
}
}
but as soon I change the Value column values it start to change the order of items in list , and if I take this in another list then I will be not able to use the ThenByDescending feature results.
This is sample code to simplify the problem , in real example these columns name come from Database and based on those columns I want to sort the list, first by first column and then by another columns mentioned. For example in MySQL it will be something like this order by col1 desc, col2 desc.
As everybody is comments is discussing the clone and then sort again the list . so here is issue with that approach.
#1. First Set sorting values in Value column for each student :
Value column first contains for each student either 1 or 0 depending on its enrollment date from the cut off date.
#2 Then on same Value column there is CGPA for each student so student should be sorted based on that.
In short all students who apply before cut off date should appear
first and then sort by descending CGPA and then students who apply
after cut off date but those also should come in descending order of
CGPA.
problem is I have only one column here for values, on which need to be sort.
Second edit :
if (_trackConfigManager.RankDependentOnFields.Any())
{
infoFields.ForEach(x => x.PropertyToCompare = _trackConfigManager.RankDependentOnFields.FirstOrDefault().FieldId);
//Order the table withrespect to the firstfield
var orderedFields = infoFields.OrderByDescending(x => x.Value);
//Then skip the first element and order the rest of the fields by descending.
foreach (var field in __trackConfigManager.RankDependentOnFields.RemoveFirst())
{
infoFields.ForEach(x => x.PropertyToCompare = field.FieldId);
orderedFields = orderedFields.ThenByDescending(x => x.Value);
}
//Format a studentId, Rank dictionary from the above orderded table
int rank = 1 + GetMaxRank(programId, statusId);
}
and RankAggregate class as follow :
public class RankAggregate
{
public student_highschool_info HsInfoObj { get; set; }
public student_interview_info IntInfoObj { get; set; }
public student StuObj { get; set; }
private student_program SpObj { get; set; }
public string PropertyToCompare { get; set; }
public bool IsDateTimeField { get; set; }
public long StudentId { get; set; }
public int Choice { get; set; }
public double Value
{
get
{
var tokens = PropertyToCompare.Split(new char[] {':'});
if (tokens.Count() > 1)
{
PropertyToCompare = (Choice == 1)
? "student_interview_FirstPrgTotalScore"
: (Choice == 2) ? "student_interview_SecondPrgTotalScore" : "dummy";
}
var fldInfo = ReflectionUtility.GetPublicPropertyName(typeof(student_highschool_info), PropertyToCompare);
if (fldInfo != null)
{
if (HsInfoObj == null)
return 0;
IsDateTimeField = (fldInfo.PropertyType == typeof(DateTime?));
if (IsDateTimeField)
{
var val1 = ReflectionUtility.GetValueOfPublicProperty(typeof(student_highschool_info),
PropertyToCompare, HsInfoObj) ?? 0;
var dt = DateTime.Parse(val1.ToString());
return -Convert.ToDouble(dt.Ticks);
}
else
{
var val1 = ReflectionUtility.GetValueOfPublicProperty(typeof(student_highschool_info),
PropertyToCompare, HsInfoObj) ?? 0;
return Convert.ToDouble(val1);
}
}
fldInfo = ReflectionUtility.GetPublicPropertyName(typeof(student_interview_info), PropertyToCompare);
if (fldInfo != null)
{
if (IntInfoObj == null)
return 0;
IsDateTimeField = (fldInfo.PropertyType == typeof(DateTime?));
if (IsDateTimeField)
{
var val1 = ReflectionUtility.GetValueOfPublicProperty(typeof(student_interview_info),
PropertyToCompare, IntInfoObj) ?? 0;
var dt = DateTime.Parse(val1.ToString());
return -Convert.ToDouble(dt.Ticks);
}
else
{
var val1 = ReflectionUtility.GetValueOfPublicProperty(typeof(student_interview_info),
PropertyToCompare, this.IntInfoObj) ?? 0;
return Convert.ToDouble(val1);
}
}
fldInfo = ReflectionUtility.GetPublicPropertyName(typeof(student), PropertyToCompare);
if (fldInfo != null)
{
if (StuObj == null)
return 0;
IsDateTimeField = (fldInfo.PropertyType == typeof(DateTime?));
if (IsDateTimeField)
{
var val1 = ReflectionUtility.GetValueOfPublicProperty(typeof(student),
PropertyToCompare, StuObj) ?? 0;
var dt = DateTime.Parse(val1.ToString());
return -Convert.ToDouble(dt.Ticks);
}
else
{
var val1 = ReflectionUtility.GetValueOfPublicProperty(typeof(student),
PropertyToCompare, this.StuObj) ?? 0;
return Convert.ToDouble(val1);
}
}
return 0.0;
}
}
public RankAggregate(long studentId, student_highschool_info _hsInfo, student_interview_info _intInfo, student _profileInfo, student_program _spInfo)
{
StudentId = studentId;
HsInfoObj = _hsInfo;
IntInfoObj = _intInfo;
StuObj = _profileInfo;
SpObj = _spInfo;
if (SpObj != null)
{
Choice = SpObj.choice;
}
}
}
Don't know why can't you add another field to the Student class, anyway since you can't do that, you have to fix these values in some places, for example using a tuple:
var studentsWithValues = students.Select(s => (s, s.Value))
.ToList();
Then after changing the values, you can sort the above array:
var orderedFields = studentsWithValues.OrderByDescending(t => t.Value)
.ThenByDescending(t => t.s.Value)
.Select(t => t.s)
Update for uncertain columns
Bind each student object with a list of values:
var studentsWithValues = students.Select(s => new
{
Student = s,
Values = new List<double> { s.Value }
})
.ToList();
After the values are updated, append each value to the binded list:
UpdateValues();
studentsWithValues.ForEach(t => t.Values.Add(t.Student.Value));
Then you can sort these values:
var e = studentsWithValues.OrderByDescending(t => t.Values[0]);
var valueCount = studentsWithValues.First().Values.Count;
for (int i = 1; i < valueCount; i++)
{
int j = i;
e = e.ThenByDescending(t => t.Values[j]);
}
var orderedFields = e.Select(t => t.Student);
Short answer
Use:
var orderedStudents = students
.OrderByDescending(student => student.Value)
.ToList();
foreach (Student student in orderedStudents) etc.
Longer answer
Your orderedFields is not a list, nor a sequence. It is an object that can be enumerated. It has not been enumerated yet. In other words: it is not a Collection<T>, it is an IEnumerable<T>. Usually in descriptions you'll find the phrases: delayed execution or deferred execution.
When you execute foreach (Student s in orderedFields), you start to enumerate the items in students. You don't enumerate the items in the original order, you enumerate them ordered by .Value.
but as soon I change the Value column values it start to change the order of items in list
So, the next time you enumerate orderedFields, the items in students are enumerated again, and ordered again by the changed value of .Value.
If you want to change the source of the items in your LINQ statement, you have to execute the delayed execution by calling one of the LINQ methods that doesn't return IEnumerable<T>, like ToList(), ToArray(), ToDictionary(), but also FirstOrDefault(), Sum(), Count(), Any()
By calling one of the non-delayed methods, the source is enumerated and the result is put in a new object. If you change the items in the new object, and use this new object as source for your next LINQ-statement, then the order of the new object is used, not the order in the original object.
Careful: if you put the references of the original items in the new List, and you change the values, you change the original items. If you don't want that, use a Select(student => new {...}) to put the values in a new object. If you change those values, the original students are not affected.
Related
I would like to extract from a list a data of an element who respect different criteria like below :
My list contains :
1, name1, Time, quantity
2, name2, Time, quantity
3, name1, Time+1, quantity+1
4, name2, Time+1, quantity+1
....
My goal :
if (MyList.Contains(name1 && name2))
{
if (name1(quantity) == name2(quantity) && name1(Time) == name2(Time))
{
return quantity;
}
}
How i create my List :
public class OCO1 : IEquatable<OCO1>
{
public DateTime OrderCreatedTime {get; set;}
public int ID {get; set;}
public decimal Quantity {get; set;}
public string Tag {get; set;}
public override string ToString()
{
return "ID: " + ID + " Name: " + Tag;
}
public override bool Equals(object obj)
{
if (obj == null) return false;
OCO1 objAsOCO1 = obj as OCO1;
if (objAsOCO1 == null) return false;
else return Equals(objAsOCO1);
}
public override int GetHashCode()
{
return ID;
}
public bool Equals(OCO1 other)
{
if (other == null) return false;
return (this.ID.Equals(other.ID));
}
// Should also override == and != operators.
}
public partial class Base
{
List<OCO1> CreatedTimeOrder = new List<OCO1>();
if (order.Tag.Equals("name1"))
{
CreatedTimeOrder.Add( new OCO1() {OrderCreatedTime = order.CreatedTime, ID = order.Id, Quantity = order.Quantity, Tag = "name1"});
}
if (order.Tag.Equals("name2"))
{
CreatedTimeOrder.Add( new OCO1() {OrderCreatedTime = order.CreatedTime, ID = order.Id, Quantity = order.Quantity, Tag = "name2"});
}
I don't see how to do that. Any help appreciate !
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If I'm understanding the question, you want to find all the records that have the same Quantity and Time values, and which contain both "name1" and "name2", and for each of these you want to select the Quantity property.
If that's correct, we can use a little System.Linq to group the items by their OrderCreatedTime and Quantity properties, filter to only the groups that have at least one item with each desired name, and then select the Quantity property from the group:
List<decimal> relevantQuantities = CreatedTimeOrder
.GroupBy(item => new {item.OrderCreatedTime, item.Quantity})
.Where(group => group.Any(item => item.Tag == "name1") &&
group.Any(item => item.Tag == "name2"))
.Select(g => g.Key.Quantity)
.ToList();
If that's not correct, please clarify exactly what you expect to be returned.
Based on the author's comment:
I want to get the quantity if the Time is the same for name1 and name2. I don't see how to explain it otherwise.
Imagine this class, abbreviated for the simplicity of this answer.
public class Data
{
public string Name { get; set; }
public int Time { get; set; }
}
And this collection
List<Data> list = new List<Data>() {
new Data() { Name = "Name1", Time = 1 },
new Data() { Name = "Name2", Time = 2 },
new Data() { Name = "Name3", Time = 3 },
new Data() { Name = "Name4", Time = 4 },
};
You can do it with LINQ
string searchArray = new string[] { "Name1", "Name2" };
// Filtering only elements with Name equals name1 or name2
var filtered = list.Where(d => searchArray.Contains(d.Name));
if(filtered.GroupBy(d => d.Time).Count() == 1) // If there is only one group of Time
return filtered.Sum(d => d.Time); // it will return 3 (1 + 2)
else
// do another thing
I have a list with two elements
element 1:
no:1,
vendor: a,
Description: Nice,
price :10
element 2:
no:1
vendor:a,
Description: Nice,
price:20
i have lot more fields in list elements so i cannot use new to sum the price
if everything is same except price i need to combine two elements into a single element by summing price.
o/p element 1:
no:1,
vendor:a,
Description:Nice,
price:30
Tried below one but not sure how to sum the price and return the entire fields with out using new
list.GroupBy(y => new { y.Description,y.vendor, y.no})
.Select(x => x.ToList().OrderBy(t => t.Price)).FirstOrDefault()
If you prefer LINQ query expressions:
var groupedElements = from element in elements
group element by new
{
element.no,
element.Description,
element.vendor
}
into grouped
select new {grouped, TotalPrice = grouped.Sum(x => x.price)};
The total price is calculated with the final .Sum method call on the grouped elements.
Try following :
class Program
{
static void Main(string[] args)
{
List<Element> elements = new List<Element>() {
new Element() { no = 1, vendor = "a", Description = "Nice", price = 10},
new Element() { no = 1, vendor = "a", Description = "Nice", price = 20}
};
List<Element> totals = elements.GroupBy(x => x.no).Select(x => new Element()
{
no = x.Key,
vendor = x.FirstOrDefault().vendor,
Description = x.FirstOrDefault().Description,
price = x.Sum(y => y.price)
}).ToList();
}
}
public class Element
{
public int no { get;set; }
public string vendor { get;set; }
public string Description { get;set; }
public decimal price { get;set; }
}
Try following using Clone
using System;
using System.Collections.Generic;
using System.Collections;
using System.Linq;
using System.Text;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
List<Element> elements = new List<Element>() {
new Element() { no = 1, vendor = "a", Description = "Nice", price = 10},
new Element() { no = 1, vendor = "a", Description = "Nice", price = 20}
};
var groups = elements.GroupBy(x => x.no).ToList();
List<Element> totals = new List<Element>();
foreach (var group in groups)
{
Element newElement = (Element)group.FirstOrDefault().Clone();
newElement.price = group.Sum(x => x.price);
totals.Add(newElement);
}
}
}
public class Element : ICloneable
{
public int no { get;set; }
public string vendor { get;set; }
public string Description { get;set; }
public decimal price { get;set; }
public object Clone()
{
return this;
}
}
}
Willy-nilly you have to create Key which has 3 properties;
If you don't like the current solution with anonymous class
list
.GroupBy(y => new {
y.Description,
y.vendor,
y.no}
)
...
You can do it in different way, e.g. with a help of unnamed tuple:
list
.GroupBy(y => Tuple.Create(
y.Description,
y.vendor,
y.no)
)
...
Or named tuple (see https://learn.microsoft.com/en-us/dotnet/csharp/tuples for details):
list
.GroupBy(y => (
Description : y.Description,
vendor : y.vendor,
no : y.no)
)
...
Or even tailored class. What's matter the most, however, is that you can't just get First item from the group
but should create a new instance. Another issue is premature materialization: .ToList() when you then get rid of this new born list and keep on querying with .OrderBy(...)
var result = result
.GroupBy(y => new {
y.Description,
y.vendor,
y.no}
)
.Select(group => MyObject() { //TODO: put the right syntax here
Description = group.Key.Description,
vendor = group.Key.vendor,
no = group.Key.no,
price = group.Sum(item => item.price) // you want to sum prices, right?
});
You need to create a custom IEqualityComparer, which when passed into the GroupBy clause, will group the items according to your needs.
Asuming the following sample class:
public class Element
{
public int no { get; set; }
public string vendor { get; set; }
public string Description { get; set; }
public decimal price { get; set; }
}
You can implement the following IEqualityComparer which using Reflection will compare every Propertypresent in the Element class except the ones defined in the Linq Where clause, in this case "price". Bear in mind further customizations could be required.
public class ElementComparer : IEqualityComparer<Element>
{
public bool Equals(Element a, Element b) => typeof(Element).GetProperties()
.Where(p => p.Name != "price")
.All(p => p.GetValue(a).Equals(p.GetValue(b)));
public int GetHashCode(Element obj) => obj.no.GetHashCode();
}
Then simply group them this way
list.GroupBy(x => x, new ElementComparer()).Select(g =>
{
// Here you need to either clone the first element of the group like
// #jdweng did, or create a new instance of Element like I'm doing below
Element element = new Element();
foreach (var prop in element.GetType().GetProperties())
{
if (prop.Name == "price")
{
prop.SetValue(element, g.Sum(y => y.price));
}
else
{
prop.SetValue(element, prop.GetValue(g.First()));
}
}
return element;
});
I think what you're trying to do is write dynamic code that groups by all properties except for the property you want to sum. This solution should work, though I loath to use reflection. A more performant method would be to use expression trees to generate an aggregation delegate that you reuse, but that is very involved. This should do the trick:
Edit: There's another answer that also seems to work. Mine assumes you will want to do this with any collection regardless of type. Doesn't require ICloneable or a type-specific IEqualityComparer<T>, though, as a slight trade-off, the other one will likely perform better in very large datasets.
static T[] GetGroupSums<T>(IEnumerable<T> collection, string sumPropertyName) where T : new()
{
//get the PropertyInfo you want to sum
//var sumProp = (PropertyInfo)((MemberExpression)((UnaryExpression)memberExpression.Body).Operand).Member;
var sumProp = typeof(T).GetProperty(sumPropertyName);
//get all PropertyInfos that are not the property to sum
var groupProps = typeof(T).GetProperties().Where(x => x != sumProp).ToArray();
//group them by a hash of non-summed properties (I got this hash method off StackExchange many years back)
var groups = collection
.GroupBy(x => GetHash(groupProps.Select(pi => pi.GetValue(x)).ToArray()))
.Select(items =>
{
var item = new T();
var firstItem = items.First();
//clone the first item
foreach (var gp in groupProps)
{
gp.SetValue(item, gp.GetValue(firstItem));
}
//Get a decimal sum and then convert back to the sum property type
var sum = items.Sum(_item => (decimal)Convert.ChangeType(sumProp.GetValue(_item), typeof(decimal)));
sumProp.SetValue(item, Convert.ChangeType(sum, sumProp.PropertyType));
//If it will always be int, just do this
//var sum = items.Sum(_item => (int)sumProp.GetValue(_item));
//sumProp.SetValue(item, sum);
return item;
});
return groups.ToArray();
}
//I got this hash method off StackExchange many years back
public static int GetHash(params object[] args)
{
unchecked
{
int hash = 17;
foreach (object arg in args)
{
hash = hash * 23 + arg.GetHashCode();
}
return hash;
}
}
Use it like this:
List<Element> elements = new List<Element>() {
new Element() { no = 1, vendor = "a", Description = "Nice", price = 10},
new Element() { no = 2, vendor = "a", Description = "Nice", price = 15},
new Element() { no = 2, vendor = "b", Description = "Nice", price = 10},
new Element() { no = 1, vendor = "a", Description = "Nice", price = 20}
};
var groups = GetGroupSums(elements, nameof(Element.price));
I have two lists of users.
In the first the users have the following fields - fname,lname, UserDetailsId,FocusStart,FocusEnd,isActive
In the second list the users have - fname, lname, UserDetailsId,totalTime, FocusStart, FocusEnd.
What I am aiming to do is : when the value isActive from the first list equals to 'true' and the userDetailsId equeals UserDetailsId from the second list I want the FocusStart and FocusEnd in the second list to be equals to the values of the matched element in the first list.
Any tips on how to achieve this?
Here is how I get the first list :
var list = listWRUD.
Join(db.UsersDetails,
o => o.UserDetailsId, od => od.identtyUserId,
(o, od) => new
{
fname = od.FirstName,
lname = od.LastName,
UserDetailsId = o.UserDetailsId,
FocusStart = o.FocusStart,
FocusEnd = o.FocusEnd,
isActive = o.isActive
}).ToList();
var a = from x in list
group x by new { x.fname, x.lname, x.UserDetailsId } into g
select new RolesUsersViewModel(g.Key.UserDetailsId, g.Key.fname, g.Key.lname, TimeSpan.FromMilliseconds(g.Sum(x => (x.FocusEnd - x.FocusStart).TotalMilliseconds)));
And here is the second one :
List<RolesUsersViewModel> list_users = a.ToList<RolesUsersViewModel>();
What i've got so far is :
var allActive = list.Where(item => item.isActive == true);
foreach (var p in list_users.Join(allActive, item => item.userId, item => item.UserDetailsId, (x, y) => new { L2 = x, L1 = y }))
{
p.L2.FocusStart = p.L1.FocusStart;
p.L2.FocusEnd = p.L1.FocusEnd;
}
Sadly, this code seems to give me some random results. A date is set to the records in the second list even if there are no records with isActive==true in the first.
The ViewModel :
public class RolesUsersViewModel
{
public RolesUsersViewModel(string userDetailsId, string FirstName, string LastName, TimeSpan totalex)
{
userId = userDetailsId;
fname = FirstName;
lname = LastName;
total = totalex;
}
public RolesUsersViewModel(DateTime focusStart, DateTime focusEnd)//
{
FocusStart = focusStart;
FocusEnd = focusEnd;
}
public string userId { get; set; }
public string fname { get; set; }
public string lname { get; set; }
public TimeSpan total { get; set; }
public DateTime FocusStart { get; set; }//
public DateTime FocusEnd { get; set; }//
}
foreach (var p in list_users)
{
// Get all the items that have matching UserDetailsId
var targets = allActive.Where(x => x.UserDetailsId == p.UserDetailsId);
// Now assign the properties
// my assumption is that the above query should return
// a single record. If my assumption is true then use
// Single or SingleOrDefault and then you do not need
// the loop below but just a simple assignment
foreach(var thisTarget in targets)
{
p.FocusStart = thisTarget.FocusStart;
p.Focused = thisTarget.FocusEnd;
}
}
I have a situation, where I get data from the database in such a way, that everything is stored in one-dimensional array.
For example:
User table: UserId, Name
Group table: GroupId, Name
UserGroup table: UserId, GroupId
As a result of joining these tables I obtain array of the following form:
result[0] = "1" // user id
result[1] = "John Doe" // user name
result[2] = "121" // group id
result[3] = "SomeGroup" // group name
result[4] = "1" // user id
result[5] = "John Doe" // user name
result[6] = "2135" // group id
result[7] = "SomeOtherGroup" // group name
I know it's not a good solution of keeping data, but these data are coming to me from some other piece of code which I am not allowed to change, so I have to deal with it.
My questions are:
Is this possible to use LINQ in order to parse this array and place data in my own objects (User class with Groups collection in it).
What is other best way to handle it if not by LINQ?
Pure linq Expression :
int i = 0;
var objects = result.GroupBy(x => Math.Floor(i++ / 4.0))
.Select(g => new { id =g.ElementAt(0), name = g.ElementAt(1), gId= g.ElementAt(2), group = g.ElementAt(3)})
.GroupBy(x=>new {x.id, x.name}, x=>new {x.gId, x.group})
.Select(y=>new {y.Key, groups = y.ToList()});
In the first GroupBy I group results in 4 elements subsets using a floor and a temporary variable.
Then The next Select put the resulting arrays in an anonymous type for better usability in the next steps.
The next GroupBy is used to group the entries by Employee. The Key will be the employee and the values will be the corresponding Groups.
Finaly the lase Selectis used to put the GroupByresult in a better shape. I choose to put the result in an other anonymous type but You could instantiate you custom objects here and put the values in the right fields using curly brace constructor.
If your logic depends on indexes LINQ is is rarely the right tool. It results in less readable, maintainable, efficient and robust code than with plain loops.
I would use something like following to create two dictionaries representing the many to many relation. Note the for-loop which increments by 4 on every iteration since that seems to be the user-group-"package":
var userIdGroups = new Dictionary<int, HashSet<Group>>();
var groupIdUsers = new Dictionary<int, HashSet<User>>();
for(int i = 0; i < result.Length; i += 4)
{
int id;
if(int.TryParse(result[i], out id))
{
string name = result.ElementAtOrDefault(i + 1);
if(name == null)
continue; // end, invalid data
User user = new User{ UserId = id, Name = name };
string groupID = result.ElementAtOrDefault(i + 2);
if(!int.TryParse(groupID, out id))
continue; // end, invalid data
name = result.ElementAtOrDefault(i + 3);
if(name == null)
continue; // end, invalid data
Group group = new Group{ GroupId = id, Name = name };
HashSet<Group> userGroups;
HashSet<User> groupUsers;
if (userIdGroups.TryGetValue(user.UserId, out userGroups))
userGroups.Add(group);
else
userIdGroups.Add(user.UserId, new HashSet<Group>{ group });
if (groupIdUsers.TryGetValue(group.GroupId, out groupUsers))
groupUsers.Add(user);
else
groupIdUsers.Add(group.GroupId, new HashSet<User> { user });
}
}
The result is:
the user-dictionary contains one user with two groups
the group-dictionary contains two groups which map to the same user
You have to override Equals and GetHashCode to compare the ID's:
class User
{
public int UserId { get; set; }
public string Name { get; set; }
public override bool Equals(object obj)
{
User u2 = obj as User;
if (u2 == null) return false;
return UserId == u2.UserId;
}
public override int GetHashCode()
{
return UserId;
}
}
class Group
{
public int GroupId { get; set; }
public string Name { get; set; }
public override bool Equals(object obj)
{
Group g2 = obj as Group;
if (g2 == null) return false;
return GroupId == g2.GroupId;
}
public override int GetHashCode()
{
return GroupId;
}
}
You can do it with the basic structures like loops:
void Main()
{
var result = new string[] {"1","John Doe","2","Joes Group","3","Jack Daniel","4","Jacks Group","5","Foo Bar","6","FooBar Group",};
List<Person> personList = new List<Person>();
List<Group> groupList = new List<Group>();
for(int i = 0; i < result.Length; i+=2)
{
i = i + 2;
//check if group does not already exist
groupList.Add(new Group() {Name = result[i+1]});
}
for(int i = 0; i < result.Length; i+=2)
{
//check if person exists.
//if person only add group to person personList.Where(x => x.Name ==result[i+1])....
personList.Add(new Person() { Id = int.Parse(result[i]),
Name = result[i+1],
Groups = new List<Group>()
{
groupList.FirstOrDefault (l => l.Name == result[i+3])
}
});
i = i+2;
}
personList.Dump();
}
public class Person
{
public Person()
{
Groups = new List<Group>();
}
public int Id { get; set; }
public string Name { get; set; }
public List<Group> Groups { get; set; }
}
public class Group
{
public string Name { get; set; }
}
// Define other methods and classes here
Output:
Please take advise: this code does not contain any validation logic, or duplicate checks. You'll have to imlpement this by yourself.
But before you implement something like this, I'd rather change the way you get your data delivered. this way you would deal with the root of your peroblems not with the symptoms.
i think no need to linq
//some class
public class Result
{
public string UserId {get;set;}
public string UserName {get;set;}
public string GroupId {get;set;}
public string GroupName {get;set;}
public string UserGroupUserId {get;set;}
public string UserGroupUserName {get;set;}
public string UserGroupId {get;set;}
public string UserGroupGroupId {get;set;}
}
// your array
private void Form1_Load(object sender, EventArgs e)
{
string[] result = new string[8];
result[0] = "1";
result[1] = "John Doe";
result[2] = "121";
result[3] = "SomeGroup";
result[4] = "1";
result[5] = "John Doe";
result[6] = "2135";
result[7] = "SomeOtherGroup";
Result r = CastResult(result);
}
// simple cast array to some type
public Result CastResult(string[] array)
{
return new Result() { UserId=array[0], UserName=array[1], GroupId=array[2], GroupName=array[3], UserGroupUserId=array[4], UserGroupUserName=array[5] , UserGroupId=array[6], UserGroupGroupId=array[7] };
}
I have 3 classes:
public class HoteAvail
{
public int HotelID { get; set; }
public string Name { get; set; }
public List<Room> Rooms { get; set; }
}
public class Room
{
public int RoomID { get; set; }
public string RoomName { get; set; }
}
public class DAL
{
public static List<HoteAvail> GetAll()
{
return new List<HoteAvail>()
{
new HoteAvail{HotelID=1,Name="Taj",Rooms=new List<Room>(){new Room{RoomID=1,RoomName="Deliux"}}},
new HoteAvail{HotelID=2,Name="x",Rooms=new List<Room>(){new Room{RoomID=2,RoomName="dd"},new Room{RoomID=1,RoomName="qq"}}},
new HoteAvail{HotelID=3,Name="y",Rooms=new List<Room>(){new Room{RoomID=3,RoomName="yy"},new Room{RoomID=1,RoomName="rr"}}},
};
}
public static List<HoteAvail> GetAllII()
{
return new List<HoteAvail>()
{
new HoteAvail{HotelID=1,Name="Taj",Rooms=new List<Room>(){new Room{RoomID=1,RoomName="Deliux"},new Room{RoomID=1,RoomName="pp"}}},
new HoteAvail{HotelID=4,Name="x",Rooms=new List<Room>(){new Room{RoomID=2,RoomName="dd"},new Room{RoomID=1,RoomName="qq"}}},
new HoteAvail{HotelID=5,Name="y",Rooms=new List<Room>(){new Room{RoomID=3,RoomName="yy"},new Room{RoomID=1,RoomName="rr"}}},
};
}
}
I want to join the values of DAL.GetAll() and DAL.GetAllII() and result should contain only those values whose HotelID doesnot matches.
The final result set should be like :
new HoteAvail{HotelID=2,Name="x",Rooms=new List<Room>(){new Room{RoomID=2,RoomName="dd"},new Room{RoomID=1,RoomName="qq"}}},
new HoteAvail{HotelID=3,Name="y",Rooms=new List<Room>(){new Room{RoomID=3,RoomName="yy"},new Room{RoomID=1,RoomName="rr"}}},
new HoteAvail{HotelID=4,Name="x",Rooms=new List<Room>(){new Room{RoomID=2,RoomName="dd"},new Room{RoomID=1,RoomName="qq"}}},
new HoteAvail{HotelID=5,Name="y",Rooms=new List<Room>(){new Room{RoomID=3,RoomName="yy"},new Room{RoomID=1,RoomName="rr"}}}
I tried:
var groupBNames = new HashSet<string>(DAL.GetAll().Select(x => x.HotelID.ToString()));
var filteredEmployees = DAL.GetAllII().Where(x => !groupBNames.Contains(x.HotelID.ToString()));
var resultList = from a in DAL.GetAll()
where !(DAL.GetAllII().Any(HotelID => HotelID == a))
select a;
But I am not getting any success. Thanks in advance.
I'd recommend doing 2 excepts using a custom IEqualityComparer. You can use this method to create the comparer:
// create a comparer to compare HotelAvail objects by hotelId
// see http://www.codeducky.org/10-utilities-c-developers-should-know-part-two/
// for the implementation of EqualityComparers.Create, which is a nice shortcut
var comparer = EqualityComparers.Create<HoteAvail>(ha => ha.HotelId); // compare by hotelId
var results =
// first take all entries in GetAll() NOT IN GetAllII()
DAL.GetAll().Except(DAL.GetAllII(), comparer)
// then add all entries in GetAllII() NOT IN GetAll()
.Concat(DAL.GetAllII()).Except(DAL.GetAll(), comparer);
You could implement a custom IEqualityComparer<HoteAvail>:
public class HoteAvailComparer: IEqualityComparer<HoteAvail>
{
public bool Equals(HoteAvail x, HoteAvail y)
{
return x != null && y != null && x.HotelID == y.HotelID;
}
public int GetHashCode(HoteAvail obj)
{
return obj.HotelID;
}
}
that you can use for Enumerable.Except which is efficient since it's using a set:
var resultList = DAL.GetAll().Except(DAL.GetAllII(), new HoteAvailComparer());
Console.WriteLine(String.Join(",", resultList.Select(h => h.HotelID))); // 2,3
Update
It is giving me HotelId 2, 3 where as I want to join the values of
DAL.GetAll() and DAL.GetAllII() and result should contain only those
values whose HotelID doesnot matchesi.e. The result should have
HotelId 2,3,4,5
Then you need to use Except from both perspectives:
var hotelComparer = new HoteAvailComparer();
var all1 = DAL.GetAll();
var all2 = DAL.GetAllII();
var resultList = all1.Except(all2, hotelComparer).Concat(all2.Except(all1, hotelComparer));
The desired result 2,3,4,5:
Console.WriteLine(String.Join(",", resultList.Select(h => h.HotelID)));
Of course you could also use Concat and GroupBy, but it's less efficient and maintainable:
resultList = all1.Concat(all2).GroupBy(h => h.HotelID)
.Where(g => g.Count() == 1)
.SelectMany(g => g);
You can use the IEqualityComparer<HoteAvail> for many other LINQ methods like GroupBy+Distinct,Join,Intersect etc.