I am trying to find in my db where an item may or may not contain particular words in its title by running a loop on an array of words. I know how to loop absolute contains on the query but i don't want to do that. here is my code:
C#
var item = "the-batman-returns-hd-version";
var id = 0;
//split slug by dash into an array
var keywords = item.Split('-'); //gives me (the, batman, returns, hd, version)
//remove any work less than 4 chracters
var result = _contentService.Products;
foreach (var word in keywords )
{
if (word.Length <= 4) continue;
var key = word;
result = result.Where(c => c.Title.Contains(key));
}
var firstOrDefault = result.FirstOrDefault();
if (firstOrDefault != null)
{
id = firstOrDefault.Id;
}
//loop query to search where all parts exist
return (id);
The above works. But the product is called "Batman Returns" so it returns 0 because it couldn't find items that contained "hd" and "version" in anything.
is there anyway to OR the looped linq. Such as:
foreach (var word in keywords )
{
if (word.Length <= 4) continue;
var key = word;
result = result.Where(c => c.Title.Contains(key) ||); //or; then loop again.
}
You can use the .Any() method:
result = result.Where(c => keywords.Any(k => c.Title.Contains(k)));
You can further filter out words less than 5 characters like it seems you might want:
result = result.Where(c => keywords.Where(k => k.Length > 4).Any(k => c.Title.Contains(k)));
Although it would be more efficient to do it once when constructing your keywords array:
var keywords = item.Split('-').Where(k => k.Length > 4).ToArray();
Related
I have a method that returns a collection that has a duplicate value.
static List<string> GenerateItems()
{
var _items = new List<string>();
_items.Add("Tase");
_items.Add("Ray");
_items.Add("Jay");
_items.Add("Bay");
_items.Add("Tase");
_items.Add("Man");
_items.Add("Ran");
_items.Add("Ban");
return _items;
}
I want to search through that collection and find the first place that duplicate value is located and start collecting all the values from the first appearance of the duplicate value to its next appearance. I want to put this in a collection but I only want the duplicate value to appear once in that collection.
This is what I have so far but.
static void Main(string[] args)
{
string key = "Tase";
var collection = GenerateItems();
int index = collection.FindIndex(a => a == key);
var matchFound = false;
var itemsBetweenKey = new List<string>();
foreach (var item in collection)
{
if (item == key)
{
matchFound = !matchFound;
}
if (matchFound)
{
itemsBetweenKey.Add(item);
}
}
foreach (var item in itemsBetweenKey)
{
Console.WriteLine(item);
}
Console.ReadLine();
}
There must be an easier way of doing this. Perhaps with Indexing or a LINQ query?
You can do something like that
string key = "Tase";
var collection = GenerateItems();
int indexStart = collection.FindIndex(a => a == key);
int indexEnd = collection.FindIndex(indexStart+1, a => a == key);
var result = collection.GetRange(indexStart, indexEnd-indexStart);
You can use linq select and group by to find the first index and last index of all duplicates (Keep in mind if something is in the list more then 2 times it would ignore the middle occurences.
But I personally think the linq for this seems overcomplicated. I would stick with simple for loops and if statements (Just turn it into a method so it reads better)
Here is a solution with Linq to get all duplicate and all values between those duplicates including itself once as you mentioned.
var collection = GenerateItems();
var Duplicates = collection.Select((x,index) => new { index, value = x })
.GroupBy(x => x.value)//group by the strings
.Where(x => x.Count() > 1)//only take duplicates
.Select(x=>new {
Value = x.Key,
FirstIndex = x.Min(y=> y.index),//take first occurenc
LastIndex = x.Max(y => y.index)//take last occurence
}).ToList();
var resultlist = new List<List<string>>();
foreach (var duplicaterange in Duplicates)
resultlist .Add(collection.GetRange(duplicaterange.FirstIndex, duplicaterange.LastIndex - duplicaterange.FirstIndex));
Try this function
public List<string> PickOut(List<string> collection, string key)
{
var index = 0;
foreach (var item in collection)
{
if (item == key)
{
return collection.Skip(index).TakeWhile(x=> x != key).ToList();
}
index++;
};
return null;
}
First finding the duplicate key then find the second occurrence of the item and then take result.
var firstduplicate = collection.GroupBy(x => x)
.Where(g => g.Count() > 1)
.Select(g => g.Key).First();
var indices = collection.Select((b, i) => b == firstduplicate ? i : -1).Where(i => i != -1).Skip(1).FirstOrDefault();
if (indices>0)
{
var result = collection.Take(indices).ToList();
}
Assume that I have a list of items from 1 - 3.
I could order them by 1,1,2,2,3,3.
But instead, I would like to order them by 1,2,3,1,2,3....
Is there an already exist function to achieve that?
This approach separates each number into groups, then iterates through the groups in order while conditionally adding them to a result list. There's probably ways to make this safer and more efficient, but this should give you a start. (It assumes that if there aren't equal counts of each number in the source array, it will skip those numbers as it runs out of them during the iteration phase.)
int[] arr = new[] { 1,1,1,2,2,2,3,3,3,4,4,4,5,5,5 };
var orderList = arr.OrderBy(x => x).Distinct().ToArray();
var refList = arr.GroupBy(x => x).ToDictionary(k => k.Key, v => v.Count());
var result = new List<int>();
int i = 0;
while (result.Count < arr.Length)
{
if (refList.Values.Sum() == 0)
break;
if (refList[orderList[i]] > 0)
{
result.Add(orderList[i]);
refList[orderList[i]]--;
}
i++;
if (i >= orderList.Length)
i = 0;
}
// Result: [1,2,3,4,5,1,2,3,4,5,1,2,3,4,5]
If we have a list of strings, then how we can find the list of strings that have the maximum number of repeated symbol by using LINQ.
List <string> mylist=new List <string>();
mylist.Add("%1");
mylist.Add("%136%250%3"); //s0
mylist.Add("%1%5%20%1%10%50%8%3"); // s1
mylist.Add("%4%255%20%1%14%50%8%4"); // s2
string symbol="%";
List <string> List_has_MAX_num_of_symbol= mylist.OrderByDescending(s => s.Length ==max_num_of(symbol)).ToList();
//the result should be a list of s1 + s2 since they have **8** repeated '%'
I tried
var longest = mylist.Where(s => s.Length == mylist.Max(m => m.Length)) ;
this gives me only one string not both
Here's a very simple solution, but not exactly efficient. Every element has the Count operation performed twice...
List<string> mylist = new List<string>();
mylist.Add("%1");
mylist.Add("%136%250%3"); //s0
mylist.Add("%1%5%20%1%10%50%8%3"); // s1
mylist.Add("%4%255%20%1%14%50%8%4"); // s2
char symbol = '%';
var maxRepeat = mylist.Max(item => item.Count(c => c == symbol));
var longest = mylist.Where(item => item.Count(c => c == symbol) == maxRepeat);
It will return 2 strings:
"%1%5%20%1%10%50%8%3"
"%4%255%20%1%14%50%8%4"
Here is an implementation that depends upon SortedDictionary<,> to get what you're after.
var mylist = new List<string> {"%1", "%136%250%3", "%1%5%20%1%10%50%8%3", "%4%255%20%1%14%50%8%4"};
var mappedValues = new SortedDictionary<int, IList<string>>();
mylist.ForEach(str =>
{
var count = str.Count(c => c == '%');
if (mappedValues.ContainsKey(count))
{
mappedValues[count].Add(str);
}
else
{
mappedValues[count] = new List<string> { str };
}
});
// output to validate output
foreach (var str in mappedValues.Last().Value)
{
Console.WriteLine(str);
}
Here's one using LINQ that gets the result you're after.
var result = (from str in mylist
group str by str.Count(c => c == '%')
into g
let max = (from gKey in g select g.Key).Max()
select new
{
Count = max,
List = (from str2 in g select str2)
}).LastOrDefault();
OK, here's my answer:
char symbol = '%';
var recs = mylist.Select(s => new { Str = s, Count = s.Count(c => c == symbol) });
var maxCount = recs.Max(x => x.Count);
var longest = recs.Where(x => x.Count == maxCount).Select(x => x.Str).ToList();
It is complicated because it has three lines (the char symbol = '%'; line excluded), but it counts each string only once. EZI's answer has only two lines, but it is complicated because it counts each string twice. If you really want a one-liner, here it is:
var longest = mylist.Where(x => x.Count(c => c == symbol) == mylist.Max(y => y.Count(c => c == symbol))).ToList();
but it counts each string many times. You can choose whatever complexity you want.
We can't assume that the % is always going to be the most repeated character in your list. First, we have to determine what character appears the most in an individual string for each string.
Once we have the character and it maximum occurrence, we can apply Linq to the List<string> and grab the strings that contain the character equal to its max occurrence.
using System;
using System.Collections.Generic;
using System.Linq;
public class Program
{
public static void Main()
{
List <string> mylist=new List <string>();
mylist.Add("%1");
mylist.Add("%136%250%3");
mylist.Add("%1%5%20%1%10%50%8%3");
mylist.Add("%4%255%20%1%14%50%8%4");
// Determine what character appears most in a single string in the list
char maxCharacter = ' ';
int maxCount = 0;
foreach (string item in mylist)
{
// Get the max occurrence of each character
int max = item.Max(m => item.Count(c => c == m));
if (max > maxCount)
{
maxCount = max;
// Store the character whose occurrence equals the max
maxCharacter = item.Select(c => c).Where(c => item.Count(i => i == c) == max).First();
}
}
// Print the strings containing the max character
mylist.Where(item => item.Count(c => c == maxCharacter) == maxCount)
.ToList().ForEach(Console.WriteLine);
}
}
Results:
%1%5%20%1%10%50%8%3
%4%255%20%1%14%50%8%4
Fiddle Demo
var newList = myList.maxBy(x=>x.Count(y=>y.Equals('%'))).ToList();
This should work. Please correct syntax if wrong anywhere and update here too if it works for you.
I need to sort a List<string> by comparing the list with a string
for example:
I have a List that contains the following Items.
Kaboki
kriiki
Kale
Kutta
Kiki
Kicki
Krishna
Kseaki
The search keyword is ki I need to sort the list items using the keyword in such a way that, the strings that match in the string start have should be first and the string having the matched string in the other position have to be in the last
Here is my current code
public static List<string> GetLocations(string prefixText)
{
try
{
DataTable dtlocs = (DataTable) HttpContext.Current.Session["locations"];
var dValue = from row in dtlocs.AsEnumerable()
where row.Field<string>("Location_Name").ToLower().Contains(prefixText.ToLower())
select row.Field<string>("Location_Name");
var results = dValue.OrderBy(s => s.IndexOf(prefixText, StringComparison.Ordinal));
var str = new List<string>(results.ToList());
if (!str.Any())
str.Add("No locations found");
return str;
}
catch (Exception)
{
var str = new List<string> {"No locations found"};
return str;
}
}
Here I'm able to get the first matched values to the top but cannot sort the remaining values
and I have another issue. there is a word King Koti and i'm searhing for Ko and this word comes to first.I think this happens because, the string has two sub strings and one of the substrings start with the matched word.
and can I make the matched letters to bold ??
var res = list.OrderBy(y=> !y.StartsWith("Ki", StringComparison.OrdinalIgnoreCase))
.ThenBy(x => x)
OrderBy orders false before true:
var result = list.OrderBy(s => !s.StartsWith("ki", StringComparison.OrdinalIgnoreCase))
.ThenBy(s => !s.ToLower().Contains("ki"));
I think this should work:
list = (from str in list
let idx = str.IndexOf(keyword, StringComparison.OrdinalIgnoreCase)
let change = idx != 0 ? idx : int.MinValue
orderby change
select str).ToList();
You can use a combination of Linq's OrderBy and the IndexOf methods:
var input = ...
var search = "ki";
var results = input.Select(Value => new { Value, Index = s.IndexOf(search, StringComparison.InvariantCultureIgnoreCase) })
.Where(pair => pair.Index >= 0)
.OrderBy(pair => pair.Index)
.Select(pair => pair.Value);
Or in query syntax:
var results =
from s in input
let i = s.IndexOf(search, StringComparison.InvariantCultureIgnoreCase)
where i >= 0
orderby i
select s;
Is there a LINQ function for this is or would one have to code it themselves like this:
static string GetLongestStringInList()
{
string longest = list[0];
foreach (string s in list)
{
if (s.Length > longest.Length)
{
longest = s;
}
}
return longest;
}
This will do it with only one loop iteration:
list.Aggregate("", (max, cur) => max.Length > cur.Length ? max : cur);
You can use this: list.OrderByDescending(s => s.Length).First();
var list = new List<string>(); // or string[] or any
list.Add("a");
list.Add("ccc");
list.Add("bb");
list.Add("eeeee");
list.Add("dddd");
// max-length
var length = list.Max(s => s.Length);
// biggest one
var biggest = list.FirstOrDefault(s => s.Length == length);
// if there is more that one by equal length
var biggestList = list.Where(s => s.Length == length);
// by ordering list
var biggest = list.OrderByDescending(s => s.Length).FirstOrDefault();
// biggest-list by LINQ
var bigList2 = from s in list where s.Length == list.Max(a => a.Length) select s;
// biggest by LINQ
var biggest2 = bigList2.FirstOrDefault();
The method you want is typically called "MaxBy" and it is unfortunately not included in the standard set of sequence operators. Fortunately it is very easy to write yourself. See this answer for an implementation:
Linq group by with a sub query
I thought there was a better way to get the longest string in a list of strings using the lambda expressions. One such way is as below.
string longestString = list.Max(arr => arr);
Hope this works good for the answer seekers.
To get the longest string in list of object/string try this:
List<String> list = new List<String>();
list.Add("HELLO");
list.Add("HELLO WORLD");
String maxString = list.OrderByDescending(x => x.Length).First();
The variable maxString will contain the value "HELLO WORLD"
Add a ThenBy() to guarantee a return order if there are multiple strings with the same length
var longest = list.OrderByDescending(s => s.Length)
.ThenBy(s => s)
.FirstOrDefault();