C List Sort by x then y

Question

Similar to List lt  gt  OrderBy Alphabetical Order  we want to sort by one element  then another   we want to achieve the functional equivalent of   SELECT   from Table ORDER BY x  y     We have a class that contains a number of sorting functions  and we have no issues sorting by one element  For example     public class MyClass       public int x      public int y       List lt MyClass gt  MyList   public void SortList         MyList Sort  MySortingFunction        And we have the following in the list     Unsorted     Sorted x      Desired ---------    ---------    --------- ID   x  y    ID   x  y    ID   x  y  0   0  1     2   0  2     0   0  1  1   1  1     0   0  1     2   0  2  2   0  2     1   1  1     1   1  1  3   1  2     3   1  2     3   1  2   Stable sort would be preferable  but not required  Solution that works for  Net 2 0 is welcome

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For versions of  Net where you can use LINQ OrderBy and ThenBy  or ThenByDescending if needed    using System Linq       List lt SomeClass gt    a  List lt SomeClass gt  b   a OrderBy x   gt  x x  ThenBy x   gt  x y  ToList        Note  for  Net 2 0  or if you can t use LINQ  see Hans Passant answer to this question

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For versions of  Net where you can use LINQ OrderBy and ThenBy  or ThenByDescending if needed    using System Linq       List lt SomeClass gt    a  List lt SomeClass gt  b   a OrderBy x   gt  x x  ThenBy x   gt  x y  ToList        Note  for  Net 2 0  or if you can t use LINQ  see Hans Passant answer to this question

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This may help you  How to Sort C  Generic List

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I had an issue where OrderBy and ThenBy did not give me the desired result  or I just didn t know how to use them correctly     I went with a list Sort solution something like this       var data    from o in database Orders Where o ClientId Equals clientId  select new       OrderId   o id      OrderDate   o orderDate      OrderBoolean    SomeClass SomeFunction o orderBoolean    1   0               data Sort  o1  o2    gt   o2 OrderBoolean CompareTo o1 OrderBoolean     0     o2 OrderBoolean CompareTo o1 OrderBoolean    o1 OrderDate Value CompareTo o2 OrderDate Value

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The trick is to implement a stable sort  I ve created a Widget class that can contain your test data   public class Widget   IComparable       int x      int y      public int X               get   return x            set   x   value               public int Y               get   return y            set   y   value               public Widget int argx  int argy                x   argx          y   argy             public int CompareTo object obj                int result   1          if  obj    null  amp  amp  obj is Widget                        Widget w   obj as Widget              result   this X CompareTo w X                     return result             static public int Compare Widget x  Widget y                int result   1          if  x    null  amp  amp  y    null                                                        result   x CompareTo y                     return result            I implemented IComparable  so it can be unstably sorted by List Sort     However  I also implemented the static method Compare  which can be passed as a delegate to a search method   I borrowed this insertion sort method from C  411    public static void InsertionSort lt T gt  IList lt T gt  list  Comparison lt T gt  comparison                                   int count   list Count              for  int j   1  j  lt  count  j                                  T key   list j                    int i   j - 1                  for    i  gt   0  amp  amp  comparison list i   key   gt  0  i--                                        list i   1    list i                                     list i   1    key                        You would put this in the sort helpers class that you mentioned in your question   Now  to use it       static void Main string   args                List lt Widget gt  widgets   new List lt Widget gt              widgets Add new Widget 0  1            widgets Add new Widget 1  1            widgets Add new Widget 0  2            widgets Add new Widget 1  2             InsertionSort lt Widget gt  widgets  Widget Compare            foreach  Widget w in widgets                        Console WriteLine w X         w Y                     And it outputs   0 1 0 2 1 1 1 2 Press any key to continue         This could probably be cleaned up with some anonymous delegates  but I ll leave that up to you   EDIT  And NoBugz demonstrates the power of anonymous methods   so  consider mine more oldschool  P

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I had an issue where OrderBy and ThenBy did not give me the desired result  or I just didn t know how to use them correctly     I went with a list Sort solution something like this       var data    from o in database Orders Where o ClientId Equals clientId  select new       OrderId   o id      OrderDate   o orderDate      OrderBoolean    SomeClass SomeFunction o orderBoolean    1   0               data Sort  o1  o2    gt   o2 OrderBoolean CompareTo o1 OrderBoolean     0     o2 OrderBoolean CompareTo o1 OrderBoolean    o1 OrderDate Value CompareTo o2 OrderDate Value

User · Answer

The trick is to implement a stable sort  I ve created a Widget class that can contain your test data   public class Widget   IComparable       int x      int y      public int X               get   return x            set   x   value               public int Y               get   return y            set   y   value               public Widget int argx  int argy                x   argx          y   argy             public int CompareTo object obj                int result   1          if  obj    null  amp  amp  obj is Widget                        Widget w   obj as Widget              result   this X CompareTo w X                     return result             static public int Compare Widget x  Widget y                int result   1          if  x    null  amp  amp  y    null                                                        result   x CompareTo y                     return result            I implemented IComparable  so it can be unstably sorted by List Sort     However  I also implemented the static method Compare  which can be passed as a delegate to a search method   I borrowed this insertion sort method from C  411    public static void InsertionSort lt T gt  IList lt T gt  list  Comparison lt T gt  comparison                                   int count   list Count              for  int j   1  j  lt  count  j                                  T key   list j                    int i   j - 1                  for    i  gt   0  amp  amp  comparison list i   key   gt  0  i--                                        list i   1    list i                                     list i   1    key                        You would put this in the sort helpers class that you mentioned in your question   Now  to use it       static void Main string   args                List lt Widget gt  widgets   new List lt Widget gt              widgets Add new Widget 0  1            widgets Add new Widget 1  1            widgets Add new Widget 0  2            widgets Add new Widget 1  2             InsertionSort lt Widget gt  widgets  Widget Compare            foreach  Widget w in widgets                        Console WriteLine w X         w Y                     And it outputs   0 1 0 2 1 1 1 2 Press any key to continue         This could probably be cleaned up with some anonymous delegates  but I ll leave that up to you   EDIT  And NoBugz demonstrates the power of anonymous methods   so  consider mine more oldschool  P

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Do keep in mind that you don t need a stable sort if you compare all members   The 2 0 solution  as requested  can look like this    public void SortList          MyList Sort delegate MyClass a  MyClass b                  int xdiff   a x CompareTo b x            if  xdiff    0  return xdiff           else return a y CompareTo b y                 Do note that this 2 0 solution is still preferable over the popular 3 5 Linq solution  it performs an in-place sort and does not have the O n  storage requirement of the Linq approach   Unless you prefer the original List object to be untouched of course

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This may help you  How to Sort C  Generic List

User · Answer

The trick is to implement a stable sort  I ve created a Widget class that can contain your test data   public class Widget   IComparable       int x      int y      public int X               get   return x            set   x   value               public int Y               get   return y            set   y   value               public Widget int argx  int argy                x   argx          y   argy             public int CompareTo object obj                int result   1          if  obj    null  amp  amp  obj is Widget                        Widget w   obj as Widget              result   this X CompareTo w X                     return result             static public int Compare Widget x  Widget y                int result   1          if  x    null  amp  amp  y    null                                                        result   x CompareTo y                     return result            I implemented IComparable  so it can be unstably sorted by List Sort     However  I also implemented the static method Compare  which can be passed as a delegate to a search method   I borrowed this insertion sort method from C  411    public static void InsertionSort lt T gt  IList lt T gt  list  Comparison lt T gt  comparison                                   int count   list Count              for  int j   1  j  lt  count  j                                  T key   list j                    int i   j - 1                  for    i  gt   0  amp  amp  comparison list i   key   gt  0  i--                                        list i   1    list i                                     list i   1    key                        You would put this in the sort helpers class that you mentioned in your question   Now  to use it       static void Main string   args                List lt Widget gt  widgets   new List lt Widget gt              widgets Add new Widget 0  1            widgets Add new Widget 1  1            widgets Add new Widget 0  2            widgets Add new Widget 1  2             InsertionSort lt Widget gt  widgets  Widget Compare            foreach  Widget w in widgets                        Console WriteLine w X         w Y                     And it outputs   0 1 0 2 1 1 1 2 Press any key to continue         This could probably be cleaned up with some anonymous delegates  but I ll leave that up to you   EDIT  And NoBugz demonstrates the power of anonymous methods   so  consider mine more oldschool  P

User · Answer

Do keep in mind that you don t need a stable sort if you compare all members   The 2 0 solution  as requested  can look like this    public void SortList          MyList Sort delegate MyClass a  MyClass b                  int xdiff   a x CompareTo b x            if  xdiff    0  return xdiff           else return a y CompareTo b y                 Do note that this 2 0 solution is still preferable over the popular 3 5 Linq solution  it performs an in-place sort and does not have the O n  storage requirement of the Linq approach   Unless you prefer the original List object to be untouched of course

User · Answer

Do keep in mind that you don t need a stable sort if you compare all members   The 2 0 solution  as requested  can look like this    public void SortList          MyList Sort delegate MyClass a  MyClass b                  int xdiff   a x CompareTo b x            if  xdiff    0  return xdiff           else return a y CompareTo b y                 Do note that this 2 0 solution is still preferable over the popular 3 5 Linq solution  it performs an in-place sort and does not have the O n  storage requirement of the Linq approach   Unless you prefer the original List object to be untouched of course

User · Answer

The trick is to implement a stable sort  I ve created a Widget class that can contain your test data   public class Widget   IComparable       int x      int y      public int X               get   return x            set   x   value               public int Y               get   return y            set   y   value               public Widget int argx  int argy                x   argx          y   argy             public int CompareTo object obj                int result   1          if  obj    null  amp  amp  obj is Widget                        Widget w   obj as Widget              result   this X CompareTo w X                     return result             static public int Compare Widget x  Widget y                int result   1          if  x    null  amp  amp  y    null                                                        result   x CompareTo y                     return result            I implemented IComparable  so it can be unstably sorted by List Sort     However  I also implemented the static method Compare  which can be passed as a delegate to a search method   I borrowed this insertion sort method from C  411    public static void InsertionSort lt T gt  IList lt T gt  list  Comparison lt T gt  comparison                                   int count   list Count              for  int j   1  j  lt  count  j                                  T key   list j                    int i   j - 1                  for    i  gt   0  amp  amp  comparison list i   key   gt  0  i--                                        list i   1    list i                                     list i   1    key                        You would put this in the sort helpers class that you mentioned in your question   Now  to use it       static void Main string   args                List lt Widget gt  widgets   new List lt Widget gt              widgets Add new Widget 0  1            widgets Add new Widget 1  1            widgets Add new Widget 0  2            widgets Add new Widget 1  2             InsertionSort lt Widget gt  widgets  Widget Compare            foreach  Widget w in widgets                        Console WriteLine w X         w Y                     And it outputs   0 1 0 2 1 1 1 2 Press any key to continue         This could probably be cleaned up with some anonymous delegates  but I ll leave that up to you   EDIT  And NoBugz demonstrates the power of anonymous methods   so  consider mine more oldschool  P

User · Answer

For versions of  Net where you can use LINQ OrderBy and ThenBy  or ThenByDescending if needed    using System Linq       List lt SomeClass gt    a  List lt SomeClass gt  b   a OrderBy x   gt  x x  ThenBy x   gt  x y  ToList        Note  for  Net 2 0  or if you can t use LINQ  see Hans Passant answer to this question

User · Answer

Do keep in mind that you don t need a stable sort if you compare all members   The 2 0 solution  as requested  can look like this    public void SortList          MyList Sort delegate MyClass a  MyClass b                  int xdiff   a x CompareTo b x            if  xdiff    0  return xdiff           else return a y CompareTo b y                 Do note that this 2 0 solution is still preferable over the popular 3 5 Linq solution  it performs an in-place sort and does not have the O n  storage requirement of the Linq approach   Unless you prefer the original List object to be untouched of course

User · Answer

For versions of  Net where you can use LINQ OrderBy and ThenBy  or ThenByDescending if needed    using System Linq       List lt SomeClass gt    a  List lt SomeClass gt  b   a OrderBy x   gt  x x  ThenBy x   gt  x y  ToList        Note  for  Net 2 0  or if you can t use LINQ  see Hans Passant answer to this question

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