C Convert List string to Dictionary string string

Question

This may seem an odd thing to want to do but ignoring that  is there a nice concise way of converting a List to Dictionary where each Key Value Pair in the Dictionary is just each string in the List  i e   List   string1  string2  string3 Dictionary   string1 string1  string2 string2  string3 string3   I have done plenty of searching and there are literally dozens of examples on Stackoverflow alone of doing it in the opposite direction but not this way round   The reason for doing this is I have two third part components and changing them is out of my hands  One returns a list of email addresses as a List and the other sends emails where the To parameter is a Dictionary  The key of the dictionary is the email address and the value is their real name  However  I don t know the real name but it still works if you set the real name to the email address as well  Therefore why I want to convert a List to a Dictionary  There are plenty of ways of doing this  A foreach loop on the list which adds a kvp to a dictionary  But I like terse code and wondered if there was a single line solution

User · Answer

You can use   var dictionary   myList ToDictionary x   gt  x

User · Answer

Try this   var res   list ToDictionary x   gt  x  x   gt  x     The first lambda lets you pick the key  the second one picks the value   You can play with it and make values differ from the keys  like this   var res   list ToDictionary x   gt  x  x   gt  string Format  Val   0    x      If your list contains duplicates  add Distinct   like this   var res   list Distinct   ToDictionary x   gt  x  x   gt  x     EDIT To comment on the valid reason  I think the only reason that could be valid for conversions like this is that at some point the keys and the values in the resultant dictionary are going to diverge  For example  you would do an initial conversion  and then replace some of the values with something else  If the keys and the values are always going to be the same  HashSet lt String gt  would provide a much better fit for your situation   var res   new HashSet lt string gt  list   if  res Contains  string1

User · Answer

By using ToDictionary   var dictionary   list ToDictionary s   gt  s     If it is possible that any string could be repeated  either do a Distinct call first on the list  to remove duplicates   or use ToLookup which allows for multiple values per key

User · Answer

Use this   var dict   list ToDictionary x   gt  x     See MSDN for more info   As Pranay points out in the comments  this will fail if an item exists in the list multiple times  Depending on your specific requirements  you can either use var dict   list Distinct   ToDictionary x   gt  x   to get a dictionary of distinct items or you can use ToLookup instead   var dict   list ToLookup x   gt  x     This will return an ILookup lt string  string gt  which is essentially the same as IDictionary lt string  IEnumerable lt string gt  gt   so you will have a list of distinct keys with each string instance under it

User · Answer

EDIT  another way to deal with duplicate is you can do like this   var dic   slist Select  element  index   gt  new element index                 ToDictionary ele  gt ele index ToString    ele  gt ele element     or     easy way to do is   var res   list ToDictionary str   gt  str  str  gt  str      but make sure that there is no string is repeating   again otherewise above code will not work for you  if there is string is repeating than its better to do like this   Dictionary lt string string gt  dic  new Dictionary lt string string gt           foreach string s in Stringlist               if  dic ContainsKey s                        dic Add  value to dictionary

[c#] C# Convert List<string> to Dictionary<string, string>

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