I am trying to search in a dictionary.
I have 2 dictionaries:
Dictionary<int, string> dict = new Dictionary<int, string>()
Dictionary<int, int> temp = new Dictionary<int, int>()
then ive populated this dictionary with:
dict.Add(123, "");
dict.Add(124, ""); //and so on
then i want to loop though this dictionary and recall the key and add that to the other dictionary
for (int i = 0; i < dict.Count; i++)
{
if (dict[i] == "")
{
temp.Add(dict[dict.ElementAt(i).Key],0);
dict[dict.ElementAt(i).Value] = "Moved";
}
}
i shall be doing other things inside this forloop so i cannot change that to a foreach loop. I am trying to check if the value of the Dictionary dict is empty then take the Key and copy the key value to the temp dictionary, but i am getting errors.
Please help :)
the problem im trying to solve is that i want to be able to search the dict dictionary for for a value with "" and take the key and store it in another dictionary temp (which will later on hold a second value). i need to do this in a for-loop as i want to be able to go back by changing the value of i.
i want to be able to use i to select both the key and value from the dict dictionary.
The errors i was getting was simply converting from string to int, i cannot get it to even store the key from dict into an int variable.
You need to put a value in the temp dictionary. I chose 0.
Dictionary<int, string> dict = new Dictionary<int, string>();
Dictionary<int, int> temp = new Dictionary<int, int>();
dict.Add(123, "");
dict.Add(124, ""); //and so on
int[] keys = dict.Keys.ToArray();
for (int i = 0; i < dict.Count; i++)
{
if (dict[keys[i]] == "")
{
temp.Add(keys[i],0);
dict[keys[i]] = "Moved";
}
}
I think this is what you're looking for:
Dictionary<int, string> dict = new Dictionary<int, string>();
List<int> temp = new List<int>();
dict.Add(123, "");
dict.Add(124, ""); //and so on
foreach (int key in dict.Keys.ToList())
{
if (dict[key] == "")
{
temp.Add(key);
dict[key] = "Moved";
}
}
}
*
First, notice temp is a List, not a Dictionary, since you're just adding the keys, no key => value (this can be changed if you can better explain why you need this as a dictionary)...
Second, notice I used dict.Keys to get all the keys in the dictionary. I also used ToList() so it can work in the foreach loop...
are you getting a compile error for the dictionary definition
Dictionary<int, int> temp = new Dictionary<int, temp>(); // int, temp?
if so,
Dictionary<int, int> temp = new Dictionary<int, int>(); // int, int
?
or, you're getting an error with this:
temp.Add(dict[dict.ElementAt(i).Key]);
because you're adding just a key, with no value. it would be something like
temp.Add(i, dict[i]); ?
if you're just using temp to hold the key values, you don't want a Dictionary, you probably HashSet (only keys, no keys+values)
if you explain exactly what you're trying to solve, this is probably something you can do trivially with a single linq statement?
Why is temp a dictionary? I would use a List<int> with all keys of the dictionary with an empty(null?) value.
List<int> keysWithEmptyValuesInDictionary = dict
.Where(kvp => string.IsNullOrEmpty(kvp.Value))
.Select(kvp => kvp.Key)
.ToList();
foreach (int key in keysWithEmptyValuesInDictionary)
{
dict[key] = "moved";
}
Related
The syntax for iterating over a dictionary with a foreach loop is:
foreach (KeyValuePair<key, value> item in dictionary)
Inside the foreach loop the key is accessed with item.key and the value with item.value.
This got me thinking, can this be used without the use of a foreach loop as a convenient (although niche) way to represent a specific dictionary pair?
I am not looking for some weird work arounds, like running a foreach loop and saving the KeyValuePair into a variable once the target key is reached, because at this point it would be more convenient to just use 2 variables.
Like this
var dic = new Dictionary<string, int>();
dic["a"] = 42;
KeyValuePair<string, int> keyVal;
foreach(var kv in dic) {
keyVal = kv; << gets the last entry from the dictioanry
}
Note that the dictionary does not store KeyValuePairs, it creates one for the enumeration, so the simple thing to do is this (because we are not expensively recreating something)
var dic = new Dictionary<string, int>();
dic["a"] = 42;
KeyValuePair<string, int> keyVal = new KeyValuePair<string, int>("a", dic["a"]);
this is more efficient than the (neat) LINQ Sinlge method
The IDictionary<TKey, TValue> interface implements IEnumerable<KeyValuePair<TKey,TValue>>. This means you can simply use Single() to get the entry you want.
IDictionary<string, int> dict = ...;
KeyValuePair<string, int> entry = dict.Single(it => it.Key == "yourKey");
try this
var dict = new Dictionary<string, string>() {
{"hi","Hello World!"},
{"adieu","Goodby"}
};
string hi = dict["hi"]; //Hello World!
or if you want a list
List<KeyValuePair<string,string>> list = dict.ToList();
result
[{"Key":"hi","Value":"Hello World!"},{"Key":"adieu","Value":"Goodby"}]
I have a dictionary of dictionary and I want to find a value from inner dictionary by Linq .
My code is:
private Dictionary<string, Dictionary<int, string>> SubCategoryDictionary = new Dictionary<string, Dictionary<int, string>>();
private Dictionary<int, string> BGA_Dictionary = new Dictionary<int, string>();
private Dictionary<int, string> Lead3D_Dictionary = new Dictionary<int, string>();
private Dictionary<int, string> Lead2D_Dictionary = new Dictionary<int, string>();
private Dictionary<int, string> Leadless_Dictionary = new Dictionary<int, string>();
private Dictionary<int, string> PIC_Dictionary = new Dictionary<int, string>();
In my constructor I have all values like this:--
BGA_Dictionary.Add(1, "Body_Measurement");
BGA_Dictionary.Add(2, "Ball_Measurement");
SubCategoryDictionary.Add("BGA", BGA_Dictionary);
Lead3D_Dictionary.Add(1, "Component_Height");
Lead3D_Dictionary.Add(2, "Rib_Measurement");
SubCategoryDictionary.Add("Package", Lead3D_Dictionary);
Lead2D_Dictionary.Add(1, "Dirt_Inspection");
Lead2D_Dictionary.Add(2, "Half_Cut_Inspection");
SubCategoryDictionary.Add("Mark", Lead2D_Dictionary);
Now I need a Lambda expression which will give me something like :
when key of SubCategoryDictionary ="Mark" and key of Lead3D_Dictionary =2 then I should get "Rib_Measurement".
I tried with following code :
string q = (from cls in SubCategoryDictionary
from s in cls.Value
where cls.Key == "Mark" && s.Key == 3
select s.Value).FirstOrDefault();
foreach (var a in q)
{
}
This above code works but I need in lambda expression. So if someone help me in formation of Lambda formation. It will be of great help.
Thanks.
I'm not sure why you ever need a lambda for accessing a dictionary by keys, but here it is:
Func<string,int,string> lambda = (k1, k2) => SubCategoryDictionary[k1][k2];
Now you can invoke it with var subCategory = lambda("Mark", 2);
I guess below code should get you the value you are trying to get.
var lead3 = SubCategoryDictionary["Mark"].SingleOrDefault(x => x.Key == 2).Value;
The idea is to use the Key of the first dictionary and get the value of it than filter it with SingleOrDefault method by providing a key to the inner dictionary value you are interested in.
Hope this helps
I have a dictionary < string,object > which has a mapping of a string and a dictionary < string,int >. How do I add a key value pair in the inside dictionary < string ,int > ?
Dictionary <string,object> dict = new Dictionary <string,object>();
Dictionary <string,int> insideDict = new Dictionary <string,int>();
// ad some values in insideDict
dict.Add("blah",insideDict);
So now the dict has a dictionary mapped with a string.Now I want to separately add values to the insideDict.
I tried
dict["blah"].Add();
Where am I going wrong?
Do you mean something like this?
var collection = new Dictionary<string, Dictionary<string, int>>();
collection.Add("some key", new Dictionary<string, int>());
collection["some key"].Add("inner key", 0);
Something like below
Dictionary<string, object> dict = new Dictionary<string, object>();
dict.Add("1", new Dictionary<string, int>());
(OR) if you already have defined the inner dictionary then
Dictionary<string, object> dict = new Dictionary<string, object>();
Dictionary<string, int> innerdict = new Dictionary<string, int>();
dict.Add("1", innerdict); // added to outer dictionary
string key = "1";
((Dictionary<string, int>)dict[key]).Add("100", 100); // added to inner dictionary
Per your comment tried this but screwed up somewhere
You didn't got it cause of your below line where you forgot to cast the inner dictionary value to Dictionary<string, int> since your outer dictionary value is object. You should rather have your outer dictionary declared strongly typed.
dict.Add("blah",insideDict); //forgot casting here
Dictionary<string, Dictionary<string,TValue>> dic = new Dictionary<string, Dictionary<string,TValue>>();
Replace the TValue with your value type.
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();
I've a class like as below:
public class Source
{
...
...
public List<Dictionary<int, int>> blanks { get; set; }
}
I've created an object of this and a Dictionary for it. I filled 'dic' Dictionary. Then, I add this dic to the blanks list.
Source src = new Source();
Dictionary<int, int> dic = new Dictionary<int, int>();
dic.Add(30, 50);
dic.Add(40, 60);
src.blanks.Add(dic);
And I try to access these 'Key' and 'Value' elements. But, I can't.
int a = src.blanks[0].Key;
int b = src.blanks[0].Value;
What can I do to access these elements?
Thanks.
src.blanks[0] is a whole dictionary, not a single KeyValuePair<int,int>. That is why you cannot access a .Key or .Value on it - there are potentially many keys, and many values associated with them.
You can access all key-value pairs in a dictionary at position zero by enumerating them, like this:
foreach (var kvp in src.blanks[0]) {
int a = kvp.Key;
int b = kvp.Value;
Console.WriteLine("Key:{0} Value:{1}", a, b);
}
blanks[0] returns a Dictionary<int, int>, you need to specify key of your item.
src.blanks[0][key]
Or loop through your values:
foreach(var pair in src.blanks[0])
{
int currentKey = pair.Key;
int currentValue = pair.Value;
}
You are trying to access a dictionary in the list which has no Key property. The Keyvaluepairs in a dictionary have keys.
So assuming you want to look into the first dictionary in the list:
Dictionary<int, int> dict = s.blanks[0];
// lookup 30:
int value = dict[30]; // 40
to get the value you should first index the list and then index the dictionary
to get value
int b = (src.blanks[0])[0]
You want something like the following:
var listItem = src.blanks[0];
var dictionaryItem = listItem[0];
var a = dictionaryItem.Key;
var b = dictionaryItem.Value;
Nevertheless, i advice you to get rid of those "nested generics" List<Dictionary<..,..>. You won't be able to distinguish what kind of object you're dealing with if you use these nested structs.
Use other structs that better represent your business logic. For example, you could derive your own class from List