I have the following data structure:
Dictionary<string, Dictionary<string, List<int>>> data =
new Dictionary<string, Dictionary<string, List<int>>>();
I want to filter some of the elements in that dictionary based on value in first element of the list of the inner dictionary.
for example:
{legion1
{soldier1, [10,1000]},
{soldier2, [50,1000]}
}
Now let's say I want to do foreach loop in which to work only elements where
the value of the first element of the list is less than 20
expected result in the foreach loop is:
{legion1{soldier1, [10,1000]}}
What I've tried:
I do foreach loop and then I want to use something similar:
data.where(x => x.value.where(o => o[0] < 20 ))
I always get error that that way is incorrect.
Please tell how can I solve the issue and why my way is failing.
You can filter and iterate over the result set like so:
var resultSet =
data.ToDictionary(e => e.Key,
e => e.Value.Where(x => x.Value[0] < 20)
.ToDictionary(k => k.Key, v => v.Value)
);
foreach(var item in resultSet){
var key = item.Key; // string
var values = item.Value; // Dictionary<string, List<int>>
...
...
}
The problem is that you are applying operator [] incorrectly. Moreover, since you want to use both Legion and Soldier, you should construct a tuple combining the two of them:
foreach (var t in data.SelectMany(lg => lg.Value.Select(s => new {
Legion = lg
, Soldier = s
})).Where(ls => ls.Soldier.Value[0] < 20)) {
Console.WriteLine("Legion={0} Soldier = {1}", t.Legion.Key, t.Soldier.Key);
}
Related
I need to return all records (items) that has a part (X) so I can use that in a group or .GroupBy afterwards
Using this summary data:
ItemName PartName
1 A
1 B
2 A
3 C
So Item1 has two parts (A,B), etc...
I need a LINQ query that will
- find all items that have part A (i.e items 1 and 2)
- return all rows for all these items
1 A
1 B
2 A
Notice that the end result returned the row (1 B) because Item1 has PartA and so I need to get back all rows for Item1.
I was looking at something like:
let items = from data in summary where data.PartName == A select new { data.ItemName } // to get all the items I need
But then, now that I have that list I need to use it to get all the rows for all items listed, and I can't seem to figure it out ...
Actual Source Code (for reference):
NOTE:
Recipe = ITEM
Ingredient = PART
(I was just trying to make it simpler)
ViewFullRecipeGrouping = (
from data in ViewRecipeSummary
group data by data.RecipeName into recipeGroup
let fullIngredientGroups = recipeGroup.GroupBy(x => x.IngredientName)
select new ViewFullRecipe()
{
RecipeName = recipeGroup.Key,
RecipeIngredients = (
from ingredientGroup in fullIngredientGroups
select new GroupIngredient()
{
IngredientName = ingredientGroup.Key
}
).ToList(),
ViewGroupRecipes = (
from data in ViewRecipeSummary
// this is where I am looking to add the new logic to define something I can then use within the next select statement that has the right data based on the information I got earlier in this query.
let a = ViewRecipeSummary.GroupBy(x => x.RecipeName)
.Where(g => g.Any(x => x.IngredientName == recipeGroup.Key))
.Select(g => new ViewRecipe()
{
RecipeName = g.Key,
IngredientName = g.Select(x => x.IngredientName)
})
select new GroupRecipe()
{
// use the new stuff here
}).ToList(),
}).ToList();
Any help would be much appreciated.
Thanks,
I believe this does what you want:
var data = /* enumerable containing rows in your table */;
var part = "X";
var items = new HashSet<int>(data
.Where(x => x.PartName == part)
.Select(x => x.ItemName));
var query = data.Where(x => items.Contains(x.ItemName));
If I understand your comment at the end, I believe this also does what you want:
var query = data
.GroupBy(x => x.ItemName)
.Where(g => g.Any(x => x.PartName == part))
.Select(g => new
{
ItemName = g.Key,
PartNames = g.Select(x => x.PartName)
});
I've an object list where each object contains an internal object list and what I would fetching is the father list (left list), however I'm forced to use SelectMany function..Is it possibile?
Naive Example:
var query = objList.SelectMany(p => p.InternalList)
.Where(internalObj => internalObj.SomeProprerty == true)
.SELECT(objList);
Is there any way to accomplish this?
Assuming you don't actually want objList, but instead the element of objList which we're looking at at the time, I think you just want:
var query = objList.SelectMany(p => p.InternalList, (o, p) => new { o, p })
.Where(pair => pair.p.SomeProperty)
.Select(pair => pair.o);
If that's not what you're after, it would really help if you'd give a concrete example.
EDIT: If you only want any example from objList where any element of the internal list has a SomeProperty value of true, you can do that more easily like this:
var value = objList.FirstOrDefault(o => o.InternalList.Any(p => p.SomeProperty));
if (value != null)
{
...
}
I am trying to use LINQ to create a Dictionary<string, List<CustomObject>> from a List<CustomObject>. I can get this to work using "var", but I don't want to use anonymous types. Here is what I have
var x = (from CustomObject o in ListOfCustomObjects
group o by o.PropertyName into t
select t.ToList());
I have also tried using Cast<>() from the LINQ library once I have x, but I get compile problems to the effect of it being an invalid cast.
Dictionary<string, List<CustomObject>> myDictionary = ListOfCustomObjects
.GroupBy(o => o.PropertyName)
.ToDictionary(g => g.Key, g => g.ToList());
I cannot comment on #Michael Blackburn, but I guess you got the downvote because the GroupBy is not necessary in this case.
Use it like:
var lookupOfCustomObjects = listOfCustomObjects.ToLookup(o=>o.PropertyName);
var listWithAllCustomObjectsWithPropertyName = lookupOfCustomObjects[propertyName]
Additionally, I've seen this perform way better than when using GroupBy().ToDictionary().
For #atari2600, this is what the answer would look like using ToLookup in lambda syntax:
var x = listOfCustomObjects
.GroupBy(o => o.PropertyName)
.ToLookup(customObject => customObject);
Basically, it takes the IGrouping and materializes it for you into a dictionary of lists, with the values of PropertyName as the key.
This might help you if you to Get a Count of words. if you want a key and a list of items just modify the code to have the value be group.ToList()
var s1 = "the best italian resturant enjoy the best pasta";
var D1Count = s1.ToLower().Split(' ').GroupBy(e => e).Select(group => new { key = group.Key, value = group.Count() }).ToDictionary(e => e.key, z => z.value);
//show the results
Console.WriteLine(D1Count["the"]);
foreach (var item in D1Count)
{
Console.WriteLine(item.Key +" "+ item.Value);
}
The following worked for me.
var temp = ctx.Set<DbTable>()
.GroupBy(g => new { g.id })
.ToDictionary(d => d.Key.id);
I decided to group the collection by length of the string.Need suggestion from you to correct myself.
string[] collection = {"five","four","ten","one"};
var groupedValues =
from w in collection
group w by w.Length into getByGroup
select getByGroup;
foreach (var g in groupedValues)
{
Console.WriteLine(g);
}
The output is :
System.Linq.Lookup....
System.Linq.Lookup....
What went wrong ?
GroupBy returns a Lookup object which contains the Key and the collection in the grouping.
foreach (var g in GroupedValues)
{
Console.WriteLine("There are {1} strings of length {0}.", g.Key, g.Count());
foreach (var v in g)
{
Console.WriteLine(" - {0}", v);
}
}
What went wrong depends on what you wanted to do!
The sequence you get back after grouping is not a flat sequence of the original objects (so in your case, it's not a sequence of strings). Otherwise how would they have been grouped?
Maybe given that you apparently expected a flat list of strings, you actually wanted to order them by length:
var collection = new[] {"five","four","ten","one"};
var byLength = collection.OrderBy(s => s.Length);
foreach (var s in GroupedValues)
Console.WriteLine(s);
Or if you wanted to group them, then you have to deal with each group in turn, and each group is a separate list of strings:
foreach (var g in GroupedValues)
{
Console.WriteLine("Strings of length " + g.Key + ":");
foreach (var s in g)
Console.WriteLine(" " + s);
}
How can I join 2 lists of equal lengths (to produce a 3rd list of equal length) where I do not want to specify a condition but simply rely on the order of items in the 2 lists.
Eg how can I join:
{1,2,3,4} with {5,6,7,8}
to produce:
{{1,5}, {2,6}, {3,7}, {4,8}}
I have tried the following:
from i in new []{1,2,3,4}
from j in new []{5,6,7,8}
select new { i, j }
but this produces a cross join. When I use join, I always need to specify the "on".
You could use Select in the first list, use the item index and access the element on the second list:
var a = new [] {1,2,3,4};
var b = new [] {5,6,7,8};
var qry = a.Select((i, index) => new {i, j = b[index]});
If you are using .Net 4.0, you can use the Zip extension method and Tuples.
var a = new [] {1,2,3,4};
var b = new [] {5,6,7,8};
var result = a.Zip(b, (an, bn) => Tuple.Create(an, bn));
Alternatively, you can keep them as arrays:
var resultArr = a.Zip(b, (an, bn) => new []{an, bn});
There is a half way solution, if you want to use query syntax. Half way in the sense that you need to use the Select method on both lists in order to get the indexes that you will use in the where clause.
int[] list1 = {1,2,3,4};
int[] list2 = {5,6,7,8};
var result = from item1 in list1.Select((value, index) => new {value, index})
from item2 in list2.Select((value, index) => new {value, index})
where item1.index == item2.index
select new {Value1 = item1.value, Value2 = item2.value};
The benefit with this solution is that it wont fail if the lists have different lengths, as the solution using the indexer would do.