Following is my function:-
public void deleteAllCarsWithType(Dictionary < KeyValuePair<string, string> , car > dictCar, string typeOfCar)
{
var keyValuePairs = dictCar.Where(keyValuePair => keyValuePair.Key.Equals(typeOfCar));
//var count = keyValuePairs.Count();
//this also gives the size of keyValuePairs as 0.
foreach (var keyValuePair in keyValuePairs)
{
dictCar.Remove(keyValuePair.Key);
}
}
KeyValuePair<string, string> which is the key of the dictionary, has carType as key and carModel as the model of the car.
When I run the unit test of it
[TestMethod]
public void DeleteSameCarTypeTest()
{
Dictionary<KeyValuePair<string, string>, car> Dictionary = new Dictionary<KeyValuePair<string, string>, car>();
Dictionary.Add(new KeyValuePair<string, string>("x", "y"), new car());
Dictionary.Add(new KeyValuePair<string, string>("x", "z"), new car());
new Program().deleteAllCarsWithType(Dictionary, "x");
Assert.AreEqual(0, Dictionary.Count);
}
It fails by saying Expected 0 and Actual 2.
When I debug it, I found out that keyValuePairs have the expected two values (which are with carType "x") but when I step into the foreach loop it's not going in and saying that count of keyValuePairs is 0. Then I tried to get the Count of the keyValuePairs which is also coming 0. I don't know what I am doing wrong. Please help me out.
keyValuePair.Key is a KeyValuePair.
You need:
var keyValuePairs = dictCar.Where(keyValuePair => keyValuePair.Key.Key.Equals(typeOfCar));
In fact a few more changes need to be made as others have pointed out:
private static void deleteAllCarsWithType(Dictionary<KeyValuePair<string, string>, car> dictCar, string typeOfCar)
{
var keyValuePairs = dictCar.Where(keyValuePair => keyValuePair.Key.Key.Equals(typeOfCar)).ToArray();
foreach (var keyValuePair in keyValuePairs)
{
dictCar.Remove(keyValuePair.Key);
}
}
You are looking into the values as opposed to the keys.
Change your code to this:
private static void deleteAllCarsWithType(Dictionary<KeyValuePair<string, string>, car> dictCar, string typeOfCar)
{
var keyValuePairs = dictCar.Keys.Where(keyValuePair => keyValuePair.Key.Equals(typeOfCar)).ToArray();
foreach (var keyValuePair in keyValuePairs)
{
dictCar.Remove(keyValuePair);
}
}
Notice I am also converting the query to an array. Otherwise the loop will fail because you modify the collection.
Related
I’m a rookie in programming and I have a problem understanding how to print elements from a List.
In the task I’ve been given, I receive:
List<Dictionary<string,string>>() list = new
List<Dictionary<string,string>>();
list.Add(processString(string, string));
list.Add(processString(string, string));
The processStrig is a Dictionary<string,string> and the keys are the same for both records.
I tried to create a new Dictionary and then populate it with foreach:
Dictionary<string,string>() dict = new Dictionary<string, string>();
foreach (Dictionary<string,string>r in list)
{
foreach (string inner in r.Keys)
{
if (!dict.ContainsKey(inner))
{
dict.Add(inner, r[inner]);
}
}
}
and then print the new dict with another foreach, but it shows me only the first input because the keys are the same. So basically my question is how to print the both inputs? The output should look like this:
The output should look like this:
[0]
"count":"some string"
"order":"some string"
[1]
"count":"some other string"
"order":"some other string"
If you are looking for a loop solution, you can try something like this:
List<Dictionary<string, string>> list = ...
for (int i = 0; i < list.Count; ++i) {
Console.WriteLine($"[{i}]");
if (list[i] == null)
Console.WriteLine("[null]");
else
foreach (var pair in list[i])
Console.WriteLine($"\"{pair.Key}\" : \"{pair.Value}\"");
}
Let's have a method that makes you a dictionary:
public static Dictionary<string, string> MakeMeADictionary(string value1, string value2){
var d = new Dictionary<string, string>();
d["key1"] = value1;
d["key2"] = value2;
return d;
}
Let's call it twice, adding the results to a List:
var listOfDicts = new List<Dictionary<string, string>>();
listOfDicts.Add(MakeMeADictionary("first val", "second val"));
listOfDicts.Add(MakeMeADictionary("third val", "fourth val"));
Let's enumerate the list, and then each dictionary inside it:
foreach(var dict in listOfDicts){
Console.WriteLine("Enumerating a dictionary");
foreach(var keyValuePair in dict)
Console.WriteLine($"Key is: {keyValuePair.Key}, Value is: {keyValuePair.Value}");
}
Result:
Enumerating a dictionary
Key is: key1, Value is: first val
Key is: key2, Value is: second val
Enumerating a dictionary
Key is: key1, Value is: third val
Key is: key2, Value is: fourth val
Strive for variable names that make your code make sense; plurals or names of colelction types for collections, foreach vars that singularly make sense for the plural being enumerated etc.. If this were a less contrived example, and e.g. it were a List<Person> I'd call it people, perhaps, and have foreach(var person in people).. I couldn't understand your choice of r in foreach(var r in list)
I am sorting a dictionary, consisting of values & keys , by value. I have a hash of words and number of time used, that I want to order by number of time used.
There is a SortedList which is good for a single value , that I want to map it back to the word.
SortedDictionary orders by key, not value.
I could use a custom class, is there a better way.
I did some google searches but I can't find exactly what I am lookign for.
I found the answer
List<KeyValuePair<string, string>> BillsList = aDictionary.ToList();
BillsList.Sort(delegate(KeyValuePair<string, string> firstPair,
KeyValuePair<string, string> nextPair)
{
return firstPair.Value.CompareTo(nextPair.Value);
}
);
This should do it:
Dictionary<string, string> d = new Dictionary<string, string>
{
{"A","Z"},
{"B","Y"},
{"C","X"}
};
d.OrderBy(x=>x.Value).Select(x=>x.Key);
Will return C, B, A.
Here is using Linq and mapping the Count to the Word:
IDictionary<string, int> wordsAndCount = new Dictionary<string, int>
{
{"Batman", 987987987},
{"MeaningOfLife",42},
{"Fun",69},
{"Relaxing",420},
{"This", 2}
};
var result = wordsAndCount.OrderBy(d => d.Value).Select(d => new
{
Word = d.Key,
Count = d.Value
});
Result:
How can i select the value from the List of keyvaluepair based on checking the key value
List<KeyValuePair<int, List<Properties>> myList = new List<KeyValuePair<int, List<Properties>>();
Here I want to get the
list myList[2].Value when myLisy[2].Key=5.
How can i achieve this?
If you need to use the List anyway I'd use LINQ for this query:
var matches = from val in myList where val.Key == 5 select val.Value;
foreach (var match in matches)
{
foreach (Property prop in match)
{
// do stuff
}
}
You may want to check the match for null.
If you're stuck with the List, you can use
myList.First(kvp => kvp.Key == 5).Value
Or if you want to use a dictionary (which might suit your needs better than the list as stated in the other answers) you can convert your list to a dictionary easily:
var dictionary = myList.ToDictionary(kvp => kvp.Key);
var value = dictionary[5].Value;
Use Dictionary<int, List<Properties>>. Then you can do
List<Properties> list = dict[5];
As in:
Dictionary<int, List<Properties>> dict = new Dictionary<int, List<Properties>>();
dict[0] = ...;
dict[1] = ...;
dict[5] = ...;
List<Properties> item5 = dict[5]; // This works if dict contains a key 5.
List<Properties> item6 = null;
// You might want to check whether the key is actually in the dictionary. Otherwise
// you might get an exception
if (dict.ContainsKey(6))
item6 = dict[6];
NOTE
The generic Dictionary class, introduced in .NET 2.0, uses KeyValuePair.
ITs better you make use of
Dictionary<TKey, TValue>.ICollection<KeyValuePair<TKey, TValue>>
and use ContainsKey Method to check the the key is there or not ..
Example :
ICollection<KeyValuePair<String, String>> openWith =
new Dictionary<String, String>();
openWith.Add(new KeyValuePair<String,String>("txt", "notepad.exe"));
openWith.Add(new KeyValuePair<String,String>("bmp", "paint.exe"));
openWith.Add(new KeyValuePair<String,String>("dib", "paint.exe"));
openWith.Add(new KeyValuePair<String,String>("rtf", "wordpad.exe"));
if (!openWith.ContainsKey("txt"))
{
Console.WriteLine("Contains Given key");
}
EDIT
To get value
string value = "";
if (openWith.TryGetValue("tif", out value))
{
Console.WriteLine("For key = \"tif\", value = {0}.", value);
//in you case
//var list= dict.Values.ToList<Property>();
}
in your caseu it will be
var list= dict.Values.ToList<Property>();
I was wondering if it were possible to make a list from the dictionary values where the key is a specified value?
The dictionary would like this:
Sidcup - DPC1
Sidcup - DPC2
Blackheath - DPC3
Blackheath - DPC4
Bexleyheath - DPC5
In fact, I'm not entirely implementing a Dictionary as above is a good idea. Here is its implementation:
DataSet ds = EngineBllUtility.GetDPCsForImportFile(connectionString, fileID);
if (ds.Tables.Count > 0)
{
DataTable dtDPCs = EngineBllUtility.GetDPCsForImportFile(connectionString, fileID).Tables[0];
Dictionary<string, string> preliminaryList = new Dictionary<string, string>();
if (dtDPCs.Columns.Contains("DPCNumber") && dtDPCs.Columns.Contains("BranchName"))
foreach (DataRow dataRow in dtDPCs.Rows)
{
preliminaryList.Add(dataRow["BranchName"].ToString(), dataRow["DPCNumber"].ToString());
}
I have the following code: (Excuse the last line, its just so you have an idea of what I'm trying to do).
foreach (string branch in branchNames)
{
string subfolder = System.IO.Path.Combine(saveLocation, branch);
System.IO.Directory.CreateDirectory(subfolder);
List<string> certificateList = new List<string>();
certificateList.Add(DPCNumber in preliminaryList where Key = branch);
}
In the above the branch is the key from the Dictionary. I need to iterate through because it needs to create a new folder and then do something with the certificateList I am creating.
Sure:
private static void TestZip()
{
Dictionary<string, string> stringstringdic = new Dictionary<string, string>();
stringstringdic.Add("1", "One");
stringstringdic.Add("2", "Two");
stringstringdic.Add("3", "Three");
stringstringdic.Add("4", "Four");
stringstringdic = stringstringdic.Where(pair => pair.Key != "1")
.ToDictionary(pair => pair.Key, pair => pair.Value);
List<string> stringlist = stringstringdic.Keys.Concat(stringstringdic.Values).ToList();
foreach (string str in stringlist)
{
Console.WriteLine(str);
}
}
//Output:
//2
//3
//4
//Two
//Three
//Four
Of course, you'll have to change the Where clause to reflect your real need.
If I understood you right, it's like .Where(pair => pair.Key == branch)
If I understand you correctly you want to add the value based on a key to a separate List?
certificateList.Add(preliminaryList[branch])
This is simplified as I really need to see the declaration of preliminaryList to know how DPCNumber fits into all of it. Could it be...
certificateList.Add(preliminaryList[branch].ToString())
To simply create a list of keys you can do the following.
var dictionary = new Dictionary<string, string>();
dictionary.Add("key1", "value1");
dictionary.Add("key2", "value2");
dictionary.Add("key3", "value3");
dictionary.Add("key4", "value4");
dictionary.Add("key5", "value5");
var list = dictionary.Keys.ToList();
This should give you a list with values "key1", "key2", "key3", "key4", "key5".
You can put a where clause in to filter out certain keys. The following gives all keys which contain a "2" (random example), resulting in just "key2".
var filteredList = dictionary.Keys.Where(key => key.Contains("2")).ToList();
Edit:
To get a value given a specific key.
string value = dictionary["key1"];
Note, the key is a dictionary must be unique, so for a given key you will only ever get a single value back and not a list of values.
i have a generic sorted list "results" with key = some filename and value = boolean.
I would like to sort the list by the boolean entry or value column. does anyone know how i can do this?
Thanks!
SortedList is optimized so that inertions occur in an ordered fashion, such that enumeration occurs in a sorted order at minimal cost. Anything else requires a re-sort. Thus:
SortedList<string,bool> l = new SortedList<string, bool>();
l.Add("a", true);
l.Add("b", false);
l.Add("c", true);
l.Add("d", false);
var orderByVal = l.OrderBy(kvp => kvp.Value);
but this enumeration will be significantly slower to calculate, and be performed up-front, requiring extra storage to do so.
Depending on your situation it might be cheaper to maintain 2 SortedList instances with the key/value reversed.
In .NET 2.0, you could add your items to a SortedList:
public static List<MyObject> SortedObjects(IEnumerable<MyObject> myList) {
SortedList<string, MyObject> sortedList = new SortedList<string, MyObject>();
foreach (MyObject object in myList) {
sortedList.Add(object.ValueIWantToSort, object);
}
return new List<MyObject>(sortedList.Values);
}
For descending all list items
list.OrderByDescending();
or
var list = list.OrderByDescending(x => x.Product.Name)
.ThenBy(x => x.Product.Price).ToList();
Normally that sorted by the first key on the list so if you swap the key and value on the add, then match that on the binding
that sample example i use and work fine
public static SortedList<string, string> GetCountries(string conn)
{
var dict = new SortedList<string, string>();
dict.Add("","Select One");
var sql = "SELECT [CountryID] ,[Descr] FROM [dbo].[Countries] Order By CountryID ";
using (var rd = GetDataReader(conn, sql))
{
while (rd.Read())
{
dict.Add(rd["Descr"].ToString(), rd["CountryID"].ToString());
}
}
return dict;
}
Dim List As SortedList(Of String, String) = VDB.CoreLib.DbUtils.GetCountries(connDB)
ddlBankCountry.DataSource = List
ddlBankCountry.DataTextField = "Key"
ddlBankCountry.DataValueField = "Value"
ddlBankCountry.DataBind()