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How to get the TValue List<> of Dictionary<>

I have a Dictionary<> that's set up as follows:
Dictionary<int, List<string>> srt = new Dictionary<int, List<string>>();
and I would like to access a specific string in the List<string> (which is the TValue in the Dictionary<>
).
For example -> Given: Dictionary<1, {"string1", "string2", "string3"}>, how can I access "string2", and only "string2" specifically.
I hope the question was clear enough to understand. If it wasn't, tell me what I need to clarify.
Thanks!

Is this what you want?
Dictionary<int, List<string>> dict = new Dictionary<int, List<string>>();
dict .Add(1, new List<string> { "Hello", "World" });
string result = fileList[1][1]; //Will output "World"

try this:
var res = srt[1][0]; //"string1"
First index is a key and second index refers to list element

You can use this
var concreteValue = str.Values.SelectMany(l => l.Where(v => v.Equals("string2")))
.FirstOrDefault();

It's pretty simple actually. Access by key to the specific list then you can treat it as an array. The syntax would be srt[key][index]
Which means to access string2 specifically you need write as var b = srt[1][1]; here b will have string2

Get Values from dictionary present in List

I have a list like,
List<string> list = new List<string>();
list.Add("MEASUREMENT");
list.Add("TEST");
I have a dictionary like,
Dictionary<string, string> dict = new Dictionary<string, string>();
dict.Add("BPGA", "TEST");
dict.Add("PPPP", "TEST");
dict.Add("RM_1000", "MEASUREMENT");
dict.Add("RM_2000", "MEASUREMENT");
dict.Add("CDMA", "TEST");
dict.Add("X100", "XXX");
Now, I want to get all matched data from dictionary based on list.
Means, all data from list match with dict value then get new dictionary with following mathched values
Is there any way to achieve this by using lambda expression?
I want result like this.
Key Value
"BPGA", "TEST"
"PPPP", "TEST"
"RM_1000", "MEASUREMENT"
"RM_2000", "MEASUREMENT"
"CDMA", "TEST"
Thanks in advance!

You should be using the dictionary like it is intended to be used i.e. a common key with multiple values for example:
Dictionary<string, List<string>> dict = new Dictionary<string, List<string>>();
Then all you need to do when adding the values is:
dict.Add("TEST", new List<string>() { /*strings go in here*/ });
Then to get all the results from a key like:
List<string> testValues = dict["TEST"];
To make it safe however you should check that the key exists i.e.
if (dict.ContainsKey("TEST"))
{
//Get the values
}
Then to add values to a current key you go do something like:
dict["TEST"].Add("NewValue");
If you insist on keeping the same structure, although I do not recommend it, something like the following will work:
List<string> testKeys = new List<string>();
foreach (var pairs in dict)
{
if (pair.Value == "TEST")
{
testKeys.Add(pair.Key);
}
}
Or even the following LINQ statement:
List<string> testKeys = dict.Where(p => p.Value == "TEST").Select(p => p.Key).ToList();
For a generic query to find the ones from your list use:
List<string> values = dict.Where(p => list.Contains(p.Value)).ToList();

Checking all entries from one Dictionary are in another Dictionary

i have two Dictionarys A & B, i want to see if all entries in A exist in B. In the past i've compared Lists using the following:
var set1 = new HashSet<String>(list1);
var set2 = new HashSet<String>(list2);
return set1.SetEquals(set2);
What i have thought to do is simply loop over each value in Dictionary A using:
dictA.TryGetValue(dictBvalue, out item)
this will return null on the item var if the value isn't there, but this seems a little long winded.
Is there a quick and effcient way of comparing dictionaries?
Thanks.

You could use All extension and do this.
var allexist = list1.All(x=> list2.ContainsKey(x.Key) && list2[x.Key] == x.Value)

here is the solution if you want to loop over each value
Dictionary<string, string> dictA = new Dictionary<string, string>();
Dictionary<string, string> dictB = new Dictionary<string, string>();
bool allexist = true;
foreach (var itemA in dictA)
{
if (!dictB.ContainsKey(itemA.Key))
{
allexist = false;
}
}

Actually, you asked for a method comparing dictionaries but your code example refer to HashSet which is different.
For HashSets, you can use IsSubsetOf and SetEquals methods.
To compare dictionaries, you can use DictionaryEquals method from this answer

How to get Distinct keys of all child dictionary elements of all parent dictionary values

I have a dictionary like this...
Dictionary<string, Dictionary<string, double>>
How to get the list of all Distinct or unique child dictionary keys from all dictionaries of all parent dictionary values (parent dictionary values is nothing but child dictionaries)?
which is the fastest way of doing this in C#?

It's really easy using LINQ:
var result = myDict.Values.SelectMany(x => x.Keys)
.Concat(myDict.Keys)
.Distinct()
.ToList();
but even without LINQ it's super easy when you use HashSet<string>:
var set = new HashSet<string>();
foreach(var outerItem in myDict)
{
set.Add(outerItem.Key);
foreach(var innerKey in item.Value.Keys)
{
set.Add(innerKey);
}
}
HashSet<T> will only keep distinct items, so adding the same string twice won't make any difference.
PS. Next time you should try writing the code first, and ask question when you run into issue you can't overcome by yourself. Stack Overflow is not 'I want code, give me code' kind of site.

Then you need to call SelectMany() on Values property of your dictionary and then use Distinct() to get distinct elements from a sequence by using the default equality comparer.
var res = myDict.Values.SelectMany(x => x.Keys).Distinct().ToList();

This code creates a Dictionary with string keys and double values.
Dictionary<string, double> d = new Dictionary<string, double>()
{
};
// Store keys in a List
List<string> list = new List<string>(d.Keys);
// Loop through list
foreach (string k in list)
{
//From here you can choose distinct key
}

If I'm reading this right:
IEnumerable<string> uniqueChildKeys = dictOfDicts
.SelectMany(d => d.Value.Keys)
.Distinct();

BinarySearch in two dimensional list

I have dimensional list:
List<List<string>> index_en_bg = new List<List<string>>();
index_en_bg.Add(new List<string>() { word1, translation1 });
index_en_bg.Add(new List<string>() { word2, translation2 });
index_en_bg.Add(new List<string>() { word3, translation3 });
I would do binary search by the first column (words), something like this:
int row = index_en_bg.BinarySearch(searchingstr);
but it works only for a one-dimensional list. How would I extend it to work for two-dimensional lists in my case? I don't want to use Dictionary class.

In this case you need to provide your own customer IComparer-implementing comparator
public class Comparer: IComparer<IList<string>>
{
public int Compare(IList<string> x, IList<string> y)
{
// base the comparison result on the first element in the respective lists
// eg basically
return x[0].CompareTo(y[0]);
}
And you'll call it like this, offering a List where only the field you're searching is filled in.
int row = index_en_bg.BinarySearch(new List<string>() {searchingstr},new Comparer());

Well as far as I understand you should use Dictionary<K,V> instead, this way:
// 1 creating the dictionary
var dic = new Dictionary<string, string>();
dic["word1"] = "translation1";
dic["word2"] = "translation2";
dic["word3"] = "translation3";
// 2 finding a translation
var trans = dic["word1"];
And Dictionary<K,V> is really performant.
But if you insist on using BinarySearch you can implement IComparer<List<string>> and pass it to the function.

As you always search using the first item of the list you could use dictionary too.
var d = Dictionary<string, List<string>>();
as answered previously it's preforms much better than List.