This one should not be too hard but my mind seems to be having a stack overflow (huehue). I have a series of Lists and I want to find all permutations they can be ordered in. All of the lists have different lengths.
For example:
List 1: 1
List 2: 1, 2
All permutations would be:
1, 1
1, 2
In my case I don't switch the numbers around. (For example 2, 1)
What is the easiest way to write this?
I can't say if the following is the easiest way, but IMO it's the most efficient way. It's basically a generalized version of the my answer to the Looking at each combination in jagged array:
public static class Algorithms
{
public static IEnumerable<T[]> GenerateCombinations<T>(this IReadOnlyList<IReadOnlyList<T>> input)
{
var result = new T[input.Count];
var indices = new int[input.Count];
for (int pos = 0, index = 0; ;)
{
for (; pos < result.Length; pos++, index = 0)
{
indices[pos] = index;
result[pos] = input[pos][index];
}
yield return result;
do
{
if (pos == 0) yield break;
index = indices[--pos] + 1;
}
while (index >= input[pos].Count);
}
}
}
You can see the explanation in the linked answer (shortly it's emulating nested loops). Also since for performace reasons it yields the internal buffer w/o cloning it, you need to clone it if you want store the result for later processing.
Sample usage:
var list1 = new List<int> { 1 };
var list2 = new List<int> { 1, 2 };
var lists = new[] { list1, list2 };
// Non caching usage
foreach (var combination in lists.GenerateCombinations())
{
// do something with the combination
}
// Caching usage
var combinations = lists.GenerateCombinations().Select(c => c.ToList()).ToList();
UPDATE: The GenerateCombinations is a standard C# iterator method, and the implementation basically emulates N nested loops (where N is the input.Count) like this (in pseudo code):
for (int i0 = 0; i0 < input[0].Count; i0++)
for (int i1 = 0; i1 < input[1].Count; i1++)
for (int i2 = 0; i2 < input[2].Count; i2++)
...
for (int iN-1 = 0; iN-1 < input[N-1].Count; iN-1++)
yield { input[0][i0], input[1][i1], input[2][i2], ..., input[N-1][iN-1] }
or showing it differently:
for (indices[0] = 0; indices[0] < input[0].Count; indices[0]++)
{
result[0] = input[0][indices[0]];
for (indices[1] = 0; indices[1] < input[1].Count; indices[1]++)
{
result[1] = input[1][indices[1]];
// ...
for (indices[N-1] = 0; indices[N-1] < input[N-1].Count; indices[N-1]++)
{
result[N-1] = input[N-1][indices[N-1]];
yield return result;
}
}
}
Nested loops:
List<int> listA = (whatever), listB = (whatever);
var answers = new List<Tuple<int,int>>;
for(int a in listA)
for(int b in listB)
answers.add(Tuple.create(a,b));
// do whatever with answers
Try this:
Func<IEnumerable<string>, IEnumerable<string>> combine = null;
combine = xs =>
xs.Skip(1).Any()
? xs.First().SelectMany(x => combine(xs.Skip(1)), (x, y) => String.Format("{0}{1}", x, y))
: xs.First().Select(x => x.ToString());
var strings = new [] { "AB", "12", "$%" };
foreach (var x in combine(strings))
{
Console.WriteLine(x);
}
That gives me:
A1$
A1%
A2$
A2%
B1$
B1%
B2$
B2%
I made the following IEnumerable<IEnumerable<TValue>> class to solve this problem which allows use of generic IEnumerable's and whose enumerator returns all permutations of the values, one from each inner list. It can be conventiently used directly in a foreach loop.
It's a variant of Michael Liu's answer to IEnumerable and Recursion using yield return
I've modified it to return lists with the permutations instead of the single values.
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
namespace Permutation
{
public class ListOfListsPermuter<TValue> : IEnumerable<IEnumerable<TValue>>
{
private int count;
private IEnumerable<TValue>[] listOfLists;
public ListOfListsPermuter(IEnumerable<IEnumerable<TValue>> listOfLists_)
{
if (object.ReferenceEquals(listOfLists_, null))
{
throw new ArgumentNullException(nameof(listOfLists_));
}
listOfLists =listOfLists_.ToArray();
count = listOfLists.Count();
for (int i = 0; i < count; i++)
{
if (object.ReferenceEquals(listOfLists[i], null))
{
throw new NullReferenceException(string.Format("{0}[{1}] is null.", nameof(listOfLists_), i));
}
}
}
// A variant of Michael Liu's answer in StackOverflow
// https://stackoverflow.com/questions/2055927/ienumerable-and-recursion-using-yield-return
public IEnumerator<IEnumerable<TValue>> GetEnumerator()
{
TValue[] currentList = new TValue[count];
int level = 0;
var enumerators = new Stack<IEnumerator<TValue>>();
IEnumerator<TValue> enumerator = listOfLists[level].GetEnumerator();
try
{
while (true)
{
if (enumerator.MoveNext())
{
currentList[level] = enumerator.Current;
level++;
if (level >= count)
{
level--;
yield return currentList;
}
else
{
enumerators.Push(enumerator);
enumerator = listOfLists[level].GetEnumerator();
}
}
else
{
if (level == 0)
{
yield break;
}
else
{
enumerator.Dispose();
enumerator = enumerators.Pop();
level--;
}
}
}
}
finally
{
// Clean up in case of an exception.
enumerator?.Dispose();
while (enumerators.Count > 0)
{
enumerator = enumerators.Pop();
enumerator.Dispose();
}
}
}
IEnumerator IEnumerable.GetEnumerator()
{
return GetEnumerator();
}
}
}
You can use it directly in a foreach like this:
public static void Main(string[] args)
{
var listOfLists = new List<List<string>>()
{
{ new List<string>() { "A", "B" } },
{ new List<string>() { "C", "D" } }
};
var permuter = new ListOfListsPermuter<string>(listOfLists);
foreach (IEnumerable<string> item in permuter)
{
Console.WriteLine("{ \"" + string.Join("\", \"", item) + "\" }");
}
}
The output:
{ "A", "C" }
{ "A", "D" }
{ "B", "C" }
{ "B", "D" }
In addition to the question: Get List<> element position in c# using LINQ
First of all, let me explaing why I do what I do :)
I'm trying to encrypt a string into a one-line code which holds how many times a letter is used in the string and also with its positions. By this method, I'll be able to decrypt the code and get(reproduce) the full text again. Let's say myString is "How are you today". I'll encrypt it like
o3[1,9,13]," "3[3,7,11],a2[4,15],y2[9,17],H1[0],w1[2],r1[5],e1[6],u1[10],t1[12],d1[14],?[18]
I know it looks odd but think about working on bigger strings like e-books. This could handle all the text in one or two lines.
The encryption is not about the security, it's just about holding big datas in smaller spaces.
In my code, I can convert the string into list, count how many times a letter is used but I can't define the positions of the letters when they occur more than once.
private void btnKoda_Click(object sender, EventArgs e)
{
var yazi = txtYazi.Text;
List<char> liste = yazi.ToList();
List<string> tut = new List<string>();
foreach (char harf in liste)
{
for (int i = 0; i < liste.Count; i++)
{
char ekle = liste[i];
tut.Add(ekle.ToString());
}
foreach (var karakter in tut)
{
txtKod.Text += karakter;
}
// holds statics
var istatistik =
from c in tut
group c by c into g
select new { g.Key, say = g.Count() };
var enCok =
from giris in istatistik
orderby giris.say descending
select giris;
foreach (var giris in enCok)
{
txtHarfler.Text += string.Format("{0}: {1}\r\n", giris.Key, giris.say);
}
break;
}
Not sure what's going on in your code, but here's how I would do it:
private void button1_Click(object sender, EventArgs e)
{
Dictionary<Char, Encoding> dct = new Dictionary<char, Encoding>();
string data = "How are you today";
for(int i = 0; i < data.Length; i++)
{
Char C = data[i];
if (!dct.ContainsKey(C))
{
dct.Add(C, new Encoding(C));
}
dct[C].AddOccurence(i);
}
StringBuilder SB = new StringBuilder();
foreach(Encoding enc in dct.Values)
{
if (SB.Length == 0)
{
SB.Append(enc.ToString());
}
else
{
SB.Append("," + enc.ToString());
}
}
Console.WriteLine(SB.ToString());
}
Here's the Encoding class:
public class Encoding
{
private Char _C;
private List<int> _Positions;
private Encoding() {}
public Encoding(Char C)
{
this._C = C;
this._Positions = new List<int>();
}
public Char Character
{
get
{
return _C;
}
}
public int Count
{
get
{
return _Positions.Count;
}
}
public int[] Occurences
{
get
{
return _Positions.ToArray();
}
}
public override string ToString()
{
string[] values = Array.ConvertAll(this.Occurences.ToArray(), x => x.ToString());
return this.Character.ToString() + this.Count.ToString() + "[" + String.Join(",", values) + "]";
}
public void AddOccurence(int position)
{
this._Positions.Add(position);
}
}
Original String:
How are you today
Output:
H1[0],o3[1,9,13],w1[2], 3[3,7,11],a2[4,15],r1[5],e1[6],y2[8,16],u1[10],t1[12],d1[14]
if I have two array
A:[A,B]
B:[1,2,3]
how can I create a string List like [A_1, A_2, A_3, B_1, B_2, B_3]
the number of array is not regular, it's maybe have 3 more
A:[A,B]
B:[1,2,3]
C:[w,x,y,z]
D:[m,n]
E:[p,q,r]
can I use recursive to solve it?
So, we define a functions Mergethat takes lists of list of stings and merges them into the string enumerable you want
static void Main(string[] args)
{
var a = new[] { "A", "B" };
var b = new[] { "1", "2", "3" };
var c = new[] { "x", "y", "z", "w" };
var result = Merge(a, b, c);
foreach (var r in result)
{
Console.WriteLine(r);
}
}
public static IList<string> Merge(params IEnumerable<string>[] lists)
{
return Merge((IEnumerable<IEnumerable<string>>) lists);
}
public static IList<string> Merge(IEnumerable<IEnumerable<string>> lists)
{
var retval = new List<string>();
var first = lists.FirstOrDefault();
if (first != null)
{
var result = Merge(lists.Skip(1));
if (result.Count > 0)
{
foreach (var x in first)
{
retval.AddRange(result.Select(y => string.Format("{0}_{1}", x, y)));
}
}
else
{
retval.AddRange(first);
}
}
return retval;
}
we can also improve this, if you use Lists as inputs
public static IList<string> Merge(params IList<string>[] lists)
{
return Merge((IList<IList<string>>) lists);
}
public static IList<string> Merge(IList<IList<string>> lists, int offset = 0)
{
if (offset >= lists.Count)
return new List<string>();
var current = lists[offset];
if (offset + 1 == lists.Count) // last entry in lists
return current;
var retval = new List<string>();
var merged = Merge(lists, offset + 1);
foreach (var x in current)
{
retval.AddRange(merged.Select(y => string.Format("{0}_{1}", x, y)));
}
return retval;
}
This is simple iterating over n-ary dimension - no need for recursion for that, just array to store indexes.
static void Iterate(int[] iterators, ArrayList[] arrays) {
for (var j = iterators.Length - 1; j >= 0; j--) {
iterators[j]++;
if (iterators[j] == arrays[j].Count) {
if (j == 0) {
break;
}
iterators[j] = 0;
} else {
break;
}
}
}
static IList<string> Merge(ArrayList[] arrays) {
List<string> result = new List<string>();
int[] iterators = new int[arrays.Length];
while (iterators[0] != arrays[0].Count) {
var builder = new StringBuilder(20);
for(var index = 0; index < arrays.Length; index++) {
if (index > 0) {
builder.Append("_");
}
builder.Append(arrays[index][iterators[index]]);
}
result.Add(builder.ToString());
Iterate(iterators, arrays);
}
return result;
}
static void Main(string[] args) {
var list1 = new ArrayList();
var list2 = new ArrayList();
var list3 = new ArrayList();
list1.Add(1);
list1.Add(2);
list2.Add("a");
list2.Add("b");
list3.Add("x");
list3.Add("y");
list3.Add("z");
var result = Merge(new[] { list1, list2, list3 });
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace arrconn {
class Program {
static string[] conn(params Array[] arrs) {
if(arrs.Length == 0) return new string[0];
if(arrs.Length == 1) {
string[] result = new string[arrs[0].Length];
for(int i = 0; i < result.Length; i++)
result[i] = arrs[0].GetValue(i).ToString();
return result; }
else {
string[] result = new string[arrs[0].Length*arrs[1].Length];
for(int i = 0; i < arrs[0].Length; i++)
for(int j = 0; j < arrs[1].Length; j++)
result[i*arrs[1].Length+j] = string.Format("{0}_{1}", arrs[0].GetValue(i), arrs[1].GetValue(j));
if(arrs.Length == 2) return result;
Array[] next = new Array[arrs.Length-1];
next[0] = result; Array.Copy(arrs, 2, next, 1, next.Length-1);
return conn(next);
}
}
static void Main(string[] args) {
foreach(string s in conn(
new string[] { "A", "B" },
new int[] { 1, 2, 3 },
new string[] { "x" },
new string[] { "$", "%", "#" }))
Console.WriteLine(s);
Console.Read();
}
}
}
I guess your input are like this:
var A = ["A","B"];
var B = [1,2,3];
var C = ["x","y","z","w"];
And what you want to obtain is:
var result = ["A_1_x", "A_1_y",...
"A_2_x", "A_2_y",...
"A_3_x", "A_3_y",...
"B_1_x", "B_1_y",...
...
..., "B_3_z", "B_3_w"];
We'll be working with IEnumerable as it will simplify the work for us and give us access to the yield keyword.
First, let's take care of the case where we only concataining two collections:
IEnumerable<string> ConcatEnumerables(IEnumerable<object> first, IEnumerable<object> second)
{
foreach (var x in first)
{
foreach (var y in second)
{
yield return x.ToString() + "_" + y.ToString();
}
}
}
Then we can recursively takle any number of collections:
IEnumerable<string> ConcatEnumerablesRec(IEnumerable<IEnumerable<object>> enums)
{
//base cases
if(!enums.Any())
{
return Enumerable.Empty<string>();
}
if (enums.Count() == 1)
{
return enums.First().Select(o => o.ToString());
}
//recursively solve the problem
return ConcatEnumerables(enums.First(), ConcatEnumerablesRec(enums.Skip(1));
}
Now you just need to call ToArray on the result if you really need an array as your output.
string[] Concatenator(params object[][] parameters)
{
return ConcatEnumerablesRec(parameters).ToArray();
}
This should do the trick. Note that the input sequences do not have to be arrays - they can be any type that implements IEnumerable<>.
Also note that we have to case sequences of value types to sequences of <object> so that they are assignable to IEnumerable<object>.
Here's the compilable Console app demo code:
using System;
using System.Collections.Generic;
using System.Linq;
namespace Demo
{
internal static class Program
{
static void Main()
{
string[] a = {"A", "B", "C", "D"};
var b = Enumerable.Range(1, 3); // <-- See how it doesn't need to be an array.
char[] c = {'X', 'Y', 'Z'};
double[] d = {-0.1, -0.2};
var sequences = new [] { a, b.Cast<object>(), c.Cast<object>(), d.Cast<object>() };
Console.WriteLine(string.Join("\n", Combine("", sequences)));
}
public static IEnumerable<string> Combine(string prefix, IEnumerable<IEnumerable<object>> sequences)
{
foreach (var item in sequences.First())
{
string current = (prefix == "") ? item.ToString() : prefix + "_" + item;
var remaining = sequences.Skip(1);
if (!remaining.Any())
{
yield return current;
}
else
{
foreach (var s in Combine(current, remaining))
yield return s;
}
}
}
}
}
I'm trying to sort an array of numbers that are strings and I'd like them to sort numerically.
The catch is that I cannot convert the numbers into int.
Here is the code:
string[] things= new string[] { "105", "101", "102", "103", "90" };
foreach (var thing in things.OrderBy(x => x))
{
Console.WriteLine(thing);
}
Output:
101, 102, 103, 105, 90
I'd like:
90, 101, 102, 103, 105
EDIT:
The output can't be 090, 101, 102...
Updated the code sample to say "things" instead of "sizes". The array can be something like this:
string[] things= new string[] { "paul", "bob", "lauren", "007", "90" };
That means it needs to be sorted alphabetically and by number:
007, 90, bob, lauren, paul
Pass a custom comparer into OrderBy. Enumerable.OrderBy will let you specify any comparer you like.
This is one way to do that:
void Main()
{
string[] things = new string[] { "paul", "bob", "lauren", "007", "90", "101"};
foreach (var thing in things.OrderBy(x => x, new SemiNumericComparer()))
{
Console.WriteLine(thing);
}
}
public class SemiNumericComparer: IComparer<string>
{
/// <summary>
/// Method to determine if a string is a number
/// </summary>
/// <param name="value">String to test</param>
/// <returns>True if numeric</returns>
public static bool IsNumeric(string value)
{
return int.TryParse(value, out _);
}
/// <inheritdoc />
public int Compare(string s1, string s2)
{
const int S1GreaterThanS2 = 1;
const int S2GreaterThanS1 = -1;
var IsNumeric1 = IsNumeric(s1);
var IsNumeric2 = IsNumeric(s2);
if (IsNumeric1 && IsNumeric2)
{
var i1 = Convert.ToInt32(s1);
var i2 = Convert.ToInt32(s2);
if (i1 > i2)
{
return S1GreaterThanS2;
}
if (i1 < i2)
{
return S2GreaterThanS1;
}
return 0;
}
if (IsNumeric1)
{
return S2GreaterThanS1;
}
if (IsNumeric2)
{
return S1GreaterThanS2;
}
return string.Compare(s1, s2, true, CultureInfo.InvariantCulture);
}
}
Just pad with zeroes to the same length:
int maxlen = sizes.Max(x => x.Length);
var result = sizes.OrderBy(x => x.PadLeft(maxlen, '0'));
Value is a string
List = List.OrderBy(c => c.Value.Length).ThenBy(c => c.Value).ToList();
Works
And, how about this ...
string[] sizes = new string[] { "105", "101", "102", "103", "90" };
var size = from x in sizes
orderby x.Length, x
select x;
foreach (var p in size)
{
Console.WriteLine(p);
}
There is a native function in windows StrCmpLogicalW that will compare in strings numbers as numbers instead of letters. It is easy to make a comparer that calls out to that function and uses it for it's comparisons.
public class StrCmpLogicalComparer : Comparer<string>
{
[DllImport("Shlwapi.dll", CharSet = CharSet.Unicode)]
private static extern int StrCmpLogicalW(string x, string y);
public override int Compare(string x, string y)
{
return StrCmpLogicalW(x, y);
}
}
It even works on strings that have both text and numbers. Here is a example program that will show the diffrence between the default sort and the StrCmpLogicalW sort
class Program
{
static void Main()
{
List<string> items = new List<string>()
{
"Example1.txt", "Example2.txt", "Example3.txt", "Example4.txt", "Example5.txt", "Example6.txt", "Example7.txt", "Example8.txt", "Example9.txt", "Example10.txt",
"Example11.txt", "Example12.txt", "Example13.txt", "Example14.txt", "Example15.txt", "Example16.txt", "Example17.txt", "Example18.txt", "Example19.txt", "Example20.txt"
};
items.Sort();
foreach (var item in items)
{
Console.WriteLine(item);
}
Console.WriteLine();
items.Sort(new StrCmpLogicalComparer());
foreach (var item in items)
{
Console.WriteLine(item);
}
Console.ReadLine();
}
}
which outputs
Example1.txt
Example10.txt
Example11.txt
Example12.txt
Example13.txt
Example14.txt
Example15.txt
Example16.txt
Example17.txt
Example18.txt
Example19.txt
Example2.txt
Example20.txt
Example3.txt
Example4.txt
Example5.txt
Example6.txt
Example7.txt
Example8.txt
Example9.txt
Example1.txt
Example2.txt
Example3.txt
Example4.txt
Example5.txt
Example6.txt
Example7.txt
Example8.txt
Example9.txt
Example10.txt
Example11.txt
Example12.txt
Example13.txt
Example14.txt
Example15.txt
Example16.txt
Example17.txt
Example18.txt
Example19.txt
Example20.txt
try this
sizes.OrderBy(x => Convert.ToInt32(x)).ToList<string>();
Note:
this will helpful when all are string convertable to int.....
You say you cannot convert the numbers into int because the array can contain elements that cannot be converted to int, but there is no harm in trying:
string[] things = new string[] { "105", "101", "102", "103", "90", "paul", "bob", "lauren", "007", "90" };
Array.Sort(things, CompareThings);
foreach (var thing in things)
Debug.WriteLine(thing);
Then compare like this:
private static int CompareThings(string x, string y)
{
int intX, intY;
if (int.TryParse(x, out intX) && int.TryParse(y, out intY))
return intX.CompareTo(intY);
return x.CompareTo(y);
}
Output: 007, 90, 90, 101, 102, 103, 105, bob, lauren, paul
This site discusses alphanumeric sorting and will sort the numbers in a logical sense instead of an ASCII sense. It also takes into account the alphas around it:
http://www.dotnetperls.com/alphanumeric-sorting
EXAMPLE:
C:/TestB/333.jpg
11
C:/TestB/33.jpg
1
C:/TestA/111.jpg
111F
C:/TestA/11.jpg
2
C:/TestA/1.jpg
111D
22
111Z
C:/TestB/03.jpg
1
2
11
22
111D
111F
111Z
C:/TestA/1.jpg
C:/TestA/11.jpg
C:/TestA/111.jpg
C:/TestB/03.jpg
C:/TestB/33.jpg
C:/TestB/333.jpg
The code is as follows:
class Program
{
static void Main(string[] args)
{
var arr = new string[]
{
"C:/TestB/333.jpg",
"11",
"C:/TestB/33.jpg",
"1",
"C:/TestA/111.jpg",
"111F",
"C:/TestA/11.jpg",
"2",
"C:/TestA/1.jpg",
"111D",
"22",
"111Z",
"C:/TestB/03.jpg"
};
Array.Sort(arr, new AlphaNumericComparer());
foreach(var e in arr) {
Console.WriteLine(e);
}
}
}
public class AlphaNumericComparer : IComparer
{
public int Compare(object x, object y)
{
string s1 = x as string;
if (s1 == null)
{
return 0;
}
string s2 = y as string;
if (s2 == null)
{
return 0;
}
int len1 = s1.Length;
int len2 = s2.Length;
int marker1 = 0;
int marker2 = 0;
// Walk through two the strings with two markers.
while (marker1 < len1 && marker2 < len2)
{
char ch1 = s1[marker1];
char ch2 = s2[marker2];
// Some buffers we can build up characters in for each chunk.
char[] space1 = new char[len1];
int loc1 = 0;
char[] space2 = new char[len2];
int loc2 = 0;
// Walk through all following characters that are digits or
// characters in BOTH strings starting at the appropriate marker.
// Collect char arrays.
do
{
space1[loc1++] = ch1;
marker1++;
if (marker1 < len1)
{
ch1 = s1[marker1];
}
else
{
break;
}
} while (char.IsDigit(ch1) == char.IsDigit(space1[0]));
do
{
space2[loc2++] = ch2;
marker2++;
if (marker2 < len2)
{
ch2 = s2[marker2];
}
else
{
break;
}
} while (char.IsDigit(ch2) == char.IsDigit(space2[0]));
// If we have collected numbers, compare them numerically.
// Otherwise, if we have strings, compare them alphabetically.
string str1 = new string(space1);
string str2 = new string(space2);
int result;
if (char.IsDigit(space1[0]) && char.IsDigit(space2[0]))
{
int thisNumericChunk = int.Parse(str1);
int thatNumericChunk = int.Parse(str2);
result = thisNumericChunk.CompareTo(thatNumericChunk);
}
else
{
result = str1.CompareTo(str2);
}
if (result != 0)
{
return result;
}
}
return len1 - len2;
}
}
I guess this will be much more good if it has some numeric in the string.
Hope it will help.
PS:I'm not sure about performance or complicated string values but it worked good something like this:
lorem ipsum
lorem ipsum 1
lorem ipsum 2
lorem ipsum 3
...
lorem ipsum 20
lorem ipsum 21
public class SemiNumericComparer : IComparer<string>
{
public int Compare(string s1, string s2)
{
int s1r, s2r;
var s1n = IsNumeric(s1, out s1r);
var s2n = IsNumeric(s2, out s2r);
if (s1n && s2n) return s1r - s2r;
else if (s1n) return -1;
else if (s2n) return 1;
var num1 = Regex.Match(s1, #"\d+$");
var num2 = Regex.Match(s2, #"\d+$");
var onlyString1 = s1.Remove(num1.Index, num1.Length);
var onlyString2 = s2.Remove(num2.Index, num2.Length);
if (onlyString1 == onlyString2)
{
if (num1.Success && num2.Success) return Convert.ToInt32(num1.Value) - Convert.ToInt32(num2.Value);
else if (num1.Success) return 1;
else if (num2.Success) return -1;
}
return string.Compare(s1, s2, true);
}
public bool IsNumeric(string value, out int result)
{
return int.TryParse(value, out result);
}
}
This seems a weird request and deserves a weird solution:
string[] sizes = new string[] { "105", "101", "102", "103", "90" };
foreach (var size in sizes.OrderBy(x => {
double sum = 0;
int position = 0;
foreach (char c in x.ToCharArray().Reverse()) {
sum += (c - 48) * (int)(Math.Pow(10,position));
position++;
}
return sum;
}))
{
Console.WriteLine(size);
}
The answer given by Jeff Paulsen is correct but the Comprarer can be much simplified to this:
public class SemiNumericComparer: IComparer<string>
{
public int Compare(string s1, string s2)
{
if (IsNumeric(s1) && IsNumeric(s2))
return Convert.ToInt32(s1) - Convert.ToInt32(s2)
if (IsNumeric(s1) && !IsNumeric(s2))
return -1;
if (!IsNumeric(s1) && IsNumeric(s2))
return 1;
return string.Compare(s1, s2, true);
}
public static bool IsNumeric(object value)
{
int result;
return Int32.TryParse(value, out result);
}
}
This works because the only thing that is checked for the result of the Comparer is if the result is larger, smaller or equal to zero. One can simply subtract the values from another and does not have to handle the return values.
Also the IsNumeric method should not have to use a try-block and can benefit from TryParse.
And for those who are not sure:
This Comparer will sort values so, that non numeric values are always appended to the end of the list. If one wants them at the beginning the second and third if block have to be swapped.
public class NaturalSort: IComparer<string>
{
[DllImport("shlwapi.dll", CharSet = CharSet.Unicode)]
public static extern int StrCmpLogicalW(string x, string y);
public int Compare(string x, string y)
{
return StrCmpLogicalW(x, y);
}
}
arr = arr.OrderBy(x => x, new NaturalSort()).ToArray();
The reason I needed it was to get filed in a directory whose filenames started with a number:
public static FileInfo[] GetFiles(string path)
{
return new DirectoryInfo(path).GetFiles()
.OrderBy(x => x.Name, new NaturalSort())
.ToArray();
}
Try this :
string[] things= new string[] { "105", "101", "102", "103", "90" };
int tmpNumber;
foreach (var thing in (things.Where(xx => int.TryParse(xx, out tmpNumber)).OrderBy(xx => int.Parse(xx))).Concat(things.Where(xx => !int.TryParse(xx, out tmpNumber)).OrderBy(xx => xx)))
{
Console.WriteLine(thing);
}
Expanding on Jeff Paulsen answer. I wanted to make sure it didn't matter how many number or char groups were in the strings:
public class SemiNumericComparer : IComparer<string>
{
public int Compare(string s1, string s2)
{
if (int.TryParse(s1, out var i1) && int.TryParse(s2, out var i2))
{
if (i1 > i2)
{
return 1;
}
if (i1 < i2)
{
return -1;
}
if (i1 == i2)
{
return 0;
}
}
var text1 = SplitCharsAndNums(s1);
var text2 = SplitCharsAndNums(s2);
if (text1.Length > 1 && text2.Length > 1)
{
for (var i = 0; i < Math.Max(text1.Length, text2.Length); i++)
{
if (text1[i] != null && text2[i] != null)
{
var pos = Compare(text1[i], text2[i]);
if (pos != 0)
{
return pos;
}
}
else
{
//text1[i] is null there for the string is shorter and comes before a longer string.
if (text1[i] == null)
{
return -1;
}
if (text2[i] == null)
{
return 1;
}
}
}
}
return string.Compare(s1, s2, true);
}
private string[] SplitCharsAndNums(string text)
{
var sb = new StringBuilder();
for (var i = 0; i < text.Length - 1; i++)
{
if ((!char.IsDigit(text[i]) && char.IsDigit(text[i + 1])) ||
(char.IsDigit(text[i]) && !char.IsDigit(text[i + 1])))
{
sb.Append(text[i]);
sb.Append(" ");
}
else
{
sb.Append(text[i]);
}
}
sb.Append(text[text.Length - 1]);
return sb.ToString().Split(' ');
}
}
I also took SplitCharsAndNums from an SO Page after amending it to deal with file names.
Example of short IComparer class.
if both string arguments can be converted to integer then arguments
are parsed to integers and compared
if only one argument can be converted to integer, then integer is
prioritized (has lower value) and are inserted before string.
If no one of arguments can be converted into integer then ordinary
string comparison is used.
Code:
public class CompareIntegerStrings : IComparer<string>
{
public int Compare(string x, string y)
{
if (int.TryParse(x, out int xOut) && int.TryParse(y, out int yOut))
return xOut.CompareTo(yOut);
else if (int.TryParse(x, out _))
return -1;
else if (int.TryParse(y, out _))
return 1;
else
return x.CompareTo(y);
}
}
In this example
List<string> intStrings = new List<string> { "01","0022","abba", "11", "deep purple", "02", };
List<string> orderedIntStrings = intStrings.OrderBy(i=>i,new CompareIntegerStrings()).ToList();
ordered list orderedIntString are { "01","02","11","0022","abba","deep purple"}.
Recommend using NaturalSort.Extension(nuget/github), as it is a reasonably difficult operation as you can see from the answer.
using NaturalSort.Extension;
var ordered = things.OrderBy(x => x, StringComparison.OrdinalIgnoreCase.WithNaturalSort());
Try this out..
string[] things = new string[] { "paul", "bob", "lauren", "007", "90", "-10" };
List<int> num = new List<int>();
List<string> str = new List<string>();
for (int i = 0; i < things.Count(); i++)
{
int result;
if (int.TryParse(things[i], out result))
{
num.Add(result);
}
else
{
str.Add(things[i]);
}
}
Now Sort the lists and merge them back...
var strsort = from s in str
orderby s.Length
select s;
var numsort = from n in num
orderby n
select n;
for (int i = 0; i < things.Count(); i++)
{
if(i < numsort.Count())
things[i] = numsort.ElementAt(i).ToString();
else
things[i] = strsort.ElementAt(i - numsort.Count());
}
I jsut tried to make a contribution in this interesting question...
My preferred solution (if all strings are numeric only):
// Order by numerical order: (Assertion: all things are numeric strings only)
foreach (var thing in things.OrderBy(int.Parse))
{
Console.Writeline(thing);
}
public class Test
{
public void TestMethod()
{
List<string> buyersList = new List<string>() { "5", "10", "1", "str", "3", "string" };
List<string> soretedBuyersList = null;
soretedBuyersList = new List<string>(SortedList(buyersList));
}
public List<string> SortedList(List<string> unsoredList)
{
return unsoredList.OrderBy(o => o, new SortNumericComparer()).ToList();
}
}
public class SortNumericComparer : IComparer<string>
{
public int Compare(string x, string y)
{
int xInt = 0;
int yInt = 0;
int result = -1;
if (!int.TryParse(x, out xInt))
{
result = 1;
}
if(int.TryParse(y, out yInt))
{
if(result == -1)
{
result = xInt - yInt;
}
}
else if(result == 1)
{
result = string.Compare(x, y, true);
}
return result;
}
}
Using Regex.Replace is so simple yet efficient. Note that the number "3" just has to be a number equal-to or larger than your longest string, so for anyone else, increase as needed.
using System.Text.RegularExpressions;
string[] things = new string[] { "105", "101", "102", "103", "90" };
foreach (var thing in things.OrderBy(x => Regex.Replace(x, #"\d+", i =>
i.Value.PadLeft(3, '0'))))
{
Console.WriteLine(thing);
}
I would have commented under recursive's answer, but my reputation is too low for that.
Because recursive's answer only works with numeric strings (if You have a string like "I am just a damn long string", it would be sorted after "Not so long string") and OP edited his answer, my Idea for the question would be to sort the strings by differentiating them into numbers and not numbers:
int maxlen = items.Max(x => x.Length);
var items = items.OrderBy(x => long.TryParse(x, out _) == true ? x.PadLeft(maxlen, '0') : x);
The underscore is for discarding the output
namespace X
{
public class Utils
{
public class StrCmpLogicalComparer : IComparer<Projects.Sample>
{
[DllImport("Shlwapi.dll", CharSet = CharSet.Unicode)]
private static extern int StrCmpLogicalW(string x, string y);
public int Compare(Projects.Sample x, Projects.Sample y)
{
string[] ls1 = x.sample_name.Split("_");
string[] ls2 = y.sample_name.Split("_");
string s1 = ls1[0];
string s2 = ls2[0];
return StrCmpLogicalW(s1, s2);
}
}
}
}
Even though this is an old question, I'd like to give a solution:
string[] things= new string[] { "105", "101", "102", "103", "90" };
foreach (var thing in things.OrderBy(x => Int32.Parse(x) )
{
Console.WriteLine(thing);
}
Woha quite simple right? :D