The fastest way to check if multiple substrings occurs at position - c#

There is a function in .NET
public static TSource ElementAt<TSource>(this IEnumerable<TSource> source, int index);
Is there a simply way to use similar function to find out if substrings occurs at some position (index)?
I mean:
public static bool ElementAtPosContains(this string, int index, string[] valuesToCheck)
{ ... }
string test1 = "abcd5f";
string[] substrings = {"1" , "2", "3", "4", "5"};
if (test.ElementAtPosContains(4, substrings))
{
DoSomething();
}
If there would be 1, 2, 3, 4, 5 at 4 position in string - return true. I can do this thing:
public static bool ElementAtPosContains(this string inputStr, int index, string[] valuesToCheck)
{
if (valuesToCheck == null)
return false;
foreach (string value in valuesToCheck)
{
if (inputStr.Substring(index, value.Length) == value)
return true;
}
return false;
}
But this seems to be not very effective

Try with this:
public static bool ElementAtPosContains(this string inputStr, int index, string[] valuesToCheck)
{
if (valuesToCheck == null || valuesToCheck.Length == 0 || inputStr.Length < index)
return false;
return valuesToCheck.Any(sub => string.CompareOrdinal(inputStr, index, sub, 0, sub.Length) == 0);
}
CompareOrdinal comparisons are always case-sensitive and don't take culture into consideration. This makes them faster then usual Compare or = operator. If you don't need culture-aware comparison or case-insensitive comparison, this method should do the job faster since it compares numeric values of characters from the string.
Demo

This seems to be smarter:
public static bool ElementAtPosContains(this string inputStr, int index, IList<String> valuesToCheck)
{
if (valuesToCheck == null || inputStr.Length < index)
return false;
return valuesToCheck.Any(s => s.Length + index <= inputStr.Length
&& inputStr.IndexOf(s, index) == index);
}
Demo
Although i think that you're doing premature optimization.

Related

Is there a function equivalent to "String.IndexOf(String[])"?

Is there any function that returns the index of the first occurrence of ANY string in a given array like: String.IndexOf(String[])?
or do I need a custom function for it?
For example the below function
"AppleBananaCherry".IndexOf(new[] {"Banana", "Cherry"});
and
"AppleBananaCherry".IndexOf(new[] {"Cherry", "Banana"});
returns 5
There is no prepared function but you can use something like this,
var sample = "AppleBananaCherry";
var input = new[] { "Cherry", "Banana" };
var result = input.Min(x => sample.IndexOf(x));
If sample has not any item of input, it returns -1
This should
public static int IndexOf(this string s, string[] values) {
var found = values
.Select(v => s.IndexOf(v))
.Where(index => index >= 0)
.OrderBy(v => v)
.Take(1)
.ToList();
return found.Count > 0 ? found[0] : -1;
}
EDIT: Removing -1 values
There is no built-in function for that, String.IndexOf() method accepts only single string or char as parameter, but you can write your own extension method, which uses IndexOf for every item in array, like in the following sample. It also should correctly exclude -1 from intermediate result
public static class Ext
{
public static int IndexOf(this string thisString, string[] values)
{
var index = thisString.Length;
var isFound = false;
foreach (var item in values)
{
var itemIndex = thisString.IndexOf(item, StringComparison.InvariantCulture);
if (itemIndex != -1 && itemIndex < index)
{
index = itemIndex;
isFound = true;
}
}
return isFound ? index : -1;
}
}
The usage example
var index = "AppleBananaCherry".IndexOf(new[] {"Banana", "Cherry"}); //returns 5
index = "AppleBananaCherry".IndexOf(new[] { "Cherry", "Banana" }); //returns 5

I'd like to divide the strings to two array

I have a string data like "aaa.bbb.ccc" or "aaa.bbb.ccc.ddd".
If I split this like "aaa.bbb.ccc".split("."), it becomes "aaa", "bbb" and "ccc".
I want to divide this to just two strings like "aaa", "bbb.ccc".
I think I can do this by firstly dividing everything and rejoining it but it's not smart way.
Is there any way to set this more smoothly?
You can set the number of splitted parts:
string myString = "aaa.bbb.ccc";
int parts = 2;
string[] myParts = myString.Split(new string[] {"."}, parts, StringSplitOptions.None);
If you want to split on the first dot character, use Substring:
String value = "aaa.bbb.ccc";
Int32 firstDotIdx = value.IndexOf( '.' );
if( firstDotIdx > -1 ) {
return new String[] {
value.Substring( 0, firstDotIdx ),
value.Substring( firstDotIdx + 1 );
}
} else {
return new String[] {
value,
"";
}
}
If you have "aaa.bbb" then it will return { "aaa", "bbb" }.
If you have "aaa.bbb.ccc" then it will return { "aaa", "bbb.ccc" }.
If you have ".aaa.bbb" then it will return { "", "aaa.bbb" }.
If you have "aaa" then it will return { "aaa", "" }.
I have a bunch of extension methods for these kind of string manipulations. An example usage for your task would look like this.
var str = "aaa.bbb.ccc.ddd";
var result = new[] { str.TakeUntil("."), str.TakeFrom(".") };
And the extension pack looks like this. The functions` results will not include the search string itself, and if the search string is not present in the input, they will return the whole input as result (this is a convention which suites my needs for this edge case, could be changed).
public static string TakeUntil(this string s, string search)
{
if (string.IsNullOrEmpty(s)) return s;
var pos = s.IndexOf(search, StringComparison.OrdinalIgnoreCase);
if (pos >= 0)
return s.Substring(0, pos);
return s;
}
public static string TakeUntilLast(this string s, string search)
{
if (string.IsNullOrEmpty(s)) return s;
var pos = s.LastIndexOf(search, StringComparison.OrdinalIgnoreCase);
if (pos >= 0)
return s.Substring(0, pos);
return s;
}
public static string TakeFrom(this string s, string search)
{
if (string.IsNullOrEmpty(s)) return s;
var pos = s.IndexOf(search, StringComparison.OrdinalIgnoreCase);
if (pos >= 0)
return s.Substring(pos + search.Length);
return s;
}
public static string TakeFromLast(this string s, string search)
{
if (string.IsNullOrEmpty(s)) return s;
var pos = s.LastIndexOf(search, StringComparison.OrdinalIgnoreCase);
if (pos >= 0)
return s.Substring(pos + search.Length);
return s;
}

sort number and alphabet string using EF

I have a column with `string type in my database that contains these value :
410
AFP-EXEC
412
411
AFP-EXEP
So i want to sort them as you can see :
_materialIssueVoucherRepository.Get().OrderBy(i=>int.Parse(i.Code)).ToList()
But it returns an obvious error Convert error string to int,The result should be like this :
410
411
412
AFP-EXEC
AFP-EXEP
The Alphabet part is not important,Can i do that in EF?
int temp;
_materialIssueVoucherRepository
.Get()
.OrderBy(i => int.TryParse(i.Code, out temp) ? temp : int.MaxValue)
.ToList()
it sounds like you want to ignore the non-numeric characters in the string and then use the integers as part of the sorting. You can try:
.OrderBy(i => int.Parse(new string(i.Where(char.IsDigit).ToArray()))
which will grab only the integers from the string for a comparison, though it's not very pretty.
You need to use a custom comparer for this purpose. Like this:
public class AlphanumComparator : IComparer<string>
{
public int Compare(string str1, string str2)
{
if (IsNumeric(str1) && IsNumeric(str2))
{
if (Convert.ToInt32(str1) > Convert.ToInt32(str2)) return 1;
if (Convert.ToInt32(str1) < Convert.ToInt32(str2)) return -1;
if (Convert.ToInt32(str1) == Convert.ToInt32(str2)) return 0;
}
if (IsNumeric(str1) && !IsNumeric(str2))
return -1;
if (!IsNumeric(str1) && IsNumeric(str2))
return 1;
return String.Compare(str1, str2, StringComparison.OrdinalIgnoreCase);
}
public static bool IsNumeric(object value)
{
try
{
int num = Convert.ToInt32(value.ToString());
return true;
}
catch (FormatException)
{
return false;
}
}
}
Then:
_materialIssueVoucherRepository.Get().OrderBy(x => x.Code, new AlphanumComparator()).ToList();

Get Max() of alphanumeric value

I have a dictionary containg ID which are alphanumeric (e.g. a10a10 & d10a9) from which I want the biggest ID, meaning 9 < 10 < a ...
When I use the following code, d10a9 is MAX since 9 is sorted before 10
var lsd = new Dictionary<string, string>();
lsd.Add("a", "d10a10");
lsd.Add("b", "d10a9");
string max = lsd.Max(kvp => kvp.Value);
How can I get the Max value of the IDs with the Longest string combined?
I think you may try to roll your own IComparer<string>
class HumanSortComparer : IComparer<string>
{
public int Compare(string x, string y)
{
// your human sorting logic here
}
}
Usage:
var last = collection.OrderBy(x => x.Value, new HumanSortComparer()).LastOrDefault();
if (last != null)
string max = last.Value;
this works like a charm assuming IDs always start with "d10a":
int max = lsd.Max(kvp => Convert.ToInt32(kvp.Value.Substring(4)));
Console.Write(string.Format("d10a{0}", max));
One way would be to do this
string max =lsd.Where(kvp=>kvp.Value.Length==lsd.Max(k=>k.Value.Length)).Max(kvp => kvp.Value);
however I think that this method would evalute the max length for each item so you may be better to extract it to a variable first
int maxLength=lsd.Max(kvp=>kvp.Value.Length);
string max = lsd.Where(kvp=>kvp.Value.Length == maxLength).Max(kvp => kvp.Value);
If you are going to have null strings in there you may need to perform null checks too
int maxLength=lsd.Max(kvp=>(kvp.Value??String.Empty).Length);
string max = lsd.Where(kvp=>(kvp.Value??String.Empty).Length == maxLength).Max(kvp => kvp.Value);
Alternatively treat your string as Base36 number and convert to long for the max function and then convert back again to get the max string.
string max =lsd.Max(tvp=>tvp.Value.FromBase36()).ToBase36();
public static class Base36 {
public static long FromBase36(this string src) {
return src.ToLower().Select(x=>(int)x<58 ? x-48 : x-87).Aggregate(0L,(s,x)=>s*36+x);
}
public static string ToBase36(this long src) {
StringBuilder result=new StringBuilder();
while(src>0) {
var digit=(int)(src % 36);
digit=(digit<10) ? digit+48 :digit+87;
result.Insert(0,(char)digit);
src=src / 36;
}
return result.ToString();
}
}
Finally just just the Agregate extension method instead of Max as this lets you do all the comparison logic....
lsd.Agregate(string.Empty,(a,b)=> a.Length == b.Length ? (a>b ? a:b) : (a.Length>b.Length ? a:b));
This could doesn't have null checks but you easily add them in.
I think if you did this:
var max = lsd.OrderByDescending(x => x.Value)
.GroupBy(x => x.Value.Length)
.OrderByDescending(x => x.Key)
.SelectMany(x => x)
.FirstOrDefault();
It may give you what you want.
You need StringComparer.OrdinalIgnoreCase.
Without the need to use linq, the function that do that is quite simple.
Complexity is, of course, O(n).
public static KeyValuePair<string, string> FindMax(IEnumerable<KeyValuePair<string, string>> lsd)
{
var comparer = StringComparer.OrdinalIgnoreCase;
var best = default(KeyValuePair<string, string>);
bool isFirst = true;
foreach (KeyValuePair<string, string> kvp in lsd)
{
if (isFirst || comparer.Compare(kvp.Value, best.Value) > 0)
{
isFirst = false;
best = kvp;
}
}
return best;
}
Okay - I think you need to first turn each key into a series of strings and numbers - since you need the whole number to be able to determine the comparison. Then you implement an IComparer - I've tested this with your two input strings as well as with a few others and it appears to do what you want. The performance could possibly be improved - but I was brainstorming it!
Create this class:
public class ValueChain
{
public readonly IEnumerable<object> Values;
public int ValueCount = 0;
private static readonly Regex _rx =
new Regex("((?<alpha>[a-z]+)|(?<numeric>([0-9]+)))",
RegexOptions.Compiled | RegexOptions.IgnoreCase);
public ValueChain(string valueString)
{
Values = Parse(valueString);
}
private IEnumerable<object> Parse(string valueString)
{
var matches = _rx.Matches(valueString);
ValueCount = matches.Count;
foreach (var match in matches.Cast<Match>())
{
if (match.Groups["alpha"].Success)
yield return match.Groups["alpha"].Value;
else if (match.Groups["numeric"].Success)
yield return int.Parse(match.Groups["numeric"].Value);
}
}
}
Now this comparer:
public class ValueChainComparer : IComparer<ValueChain>
{
private IComparer<string> StringComparer;
public ValueChainComparer()
: this(global::System.StringComparer.OrdinalIgnoreCase)
{
}
public ValueChainComparer(IComparer<string> stringComparer)
{
StringComparer = stringComparer;
}
#region IComparer<ValueChain> Members
public int Compare(ValueChain x, ValueChain y)
{
//todo: null checks
int comparison = 0;
foreach (var pair in x.Values.Zip
(y.Values, (xVal, yVal) => new { XVal = xVal, YVal = yVal }))
{
//types match?
if (pair.XVal.GetType().Equals(pair.YVal.GetType()))
{
if (pair.XVal is string)
comparison = StringComparer.Compare(
(string)pair.XVal, (string)pair.YVal);
else if (pair.XVal is int) //unboxing here - could be changed
comparison = Comparer<int>.Default.Compare(
(int)pair.XVal, (int)pair.YVal);
if (comparison != 0)
return comparison;
}
else //according to your rules strings are always greater than numbers.
{
if (pair.XVal is string)
return 1;
else
return -1;
}
}
if (comparison == 0) //ah yes, but were they the same length?
{
//whichever one has the most values is greater
return x.ValueCount == y.ValueCount ?
0 : x.ValueCount < y.ValueCount ? -1 : 1;
}
return comparison;
}
#endregion
}
Now you can get the max using OrderByDescending on an IEnumerable<ValueChain> and FirstOrDefault:
[TestMethod]
public void TestMethod1()
{
List<ValueChain> values = new List<ValueChain>(new []
{
new ValueChain("d10a9"),
new ValueChain("d10a10")
});
ValueChain max =
values.OrderByDescending(v => v, new ValueChainComparer()).FirstOrDefault();
}
So you can use this to sort the string values in your dictionary:
var maxKvp = lsd.OrderByDescending(kvp => new ValueChain(kvp.Value),
new ValueChainComparer()).FirstOrDefault();

How do I sort strings alphabetically while accounting for value when a string is numeric?

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

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