I have a string of the format
"key1=value1;key2=value2;key3=value3;"
I need to convert it to a dictionary for the above mentioned key value pairs.
What would be the best way to go about this?
Thanks.
Something like this?
var dict = text.Split(new[] {';'}, StringSplitOptions.RemoveEmptyEntries)
.Select(part => part.Split('='))
.ToDictionary(split => split[0], split => split[1]);
Of course, this will fail if the assumptions aren't met. For example, an IndexOutOfRangeException could be thrown if the text isn't in the right format and an ArgumentException will be thrown if there are duplicate keys. Each of these scenarios will require different modifications. If redundant white-space could be present, you may need some string.Trim calls as necessary.
Updated Ani's to take in account the semi colon at the end. The where clause will ensure that you have a key and value before creating and entry.
var dictionary = "key1=value1;key2=value2;key3=value3;"
.Split(';')
.Select (part => part.Split('='))
.Where (part => part.Length == 2)
.ToDictionary (sp => sp[0], sp => sp[1]);
You could do this using JSON string, for example:
var dic = JsonConvert.DeserializeObject<Dictionary<int, string>>("{'1':'One','2':'Two','3':'Three'}");
Behold the awesome whitespace ignoring, correcting for last value having or not having a semicolon power of regular expressions:
var dict = Regex.Matches("key1 = value1; key2 = value2 ; key3 = value3", #"\s*(.*?)\s*=\s*(.*?)\s*(;|$)")
.OfType<Match>()
.ToDictionary(m => m.Groups[1].Value, m => m.Groups[2].Value);
But seriously though, Ani deserves props for the .ToDictionary(). I would never have thought of that.
You could write it like this or loop over it to do it yourself. Either way. Ultimately, you're splitting on ; to get the item pairs, then on = to get the key and value.
string input = "key1=value1;key2=value2;key3=value3;";
Dictionary<string, string> dictionary =
input.TrimEnd(';').Split(';').ToDictionary(item => item.Split('=')[0], item => item.Split('=')[1]);
Loop version:
Dictionary<string, string> dictionary = new Dictionary<string, string>();
string[] items = input.TrimEnd(';').Split(';');
foreach (string item in items)
{
string[] keyValue = item.Split('=');
dictionary.Add(keyValue[0], keyValue[1]);
}
Related
I have this input string and need to extract values of Uid, pwd and Dsn attributes...
I am splitting the values using ; char and then replacing Uid ="" and that's how I am reading values for other attributes too...
String[] test = "Uid=test;Pwd=abc;dsn=xxx".split(';')
id = test[0].Replace("Uid=", "");
pwd = test[0].Replace("Pwd", "");
datasrc = test[0].Replace("Dsn", "");
Is there any better approach to extract values from string[] ?
I suggest using Dictionary<String, String> and, yes, Linq to materialize the initial string into it:
string test = "Uid=test;Pwd=abc;dsn=xxx";
Dictionary<string, string> dict = test
.Split(';')
.Select(item => item.Split('='))
.ToDictionary(pair => pair[0], pair => pair[1], StringComparer.OrdinalIgnoreCase);
...
var id = dict["Uid"];
var pwd = dict["Pwd"];
var datasrc = dict["Dsn"]; // please, notice that the name is case insensitive
You can project after splitting and then split on = character and pick the second index, but it would only work, if the string is guaranteed to be always in this format, then this should work for you:
var result = "Uid=test;Pwd=abc;dsn=xxx".Split(';')
.Select(x=> x.Split('=')[1]);
Result:
See the working DEMO Fiddle
Somewhat similar to this question:
Where do I put the "orderby group.key" in this LINQ statement?
Except I'm using Dynamic.Linq which makes this a bit harder. I have a bunch of data coming from a database and then I'm grouping by some field and then outputing the result. The problem is that the ordering of the groups seems to randomly jump around which isn't very convenient for the end-user. So taking inspiration from the linked question, if I had this:
string[] words = { "boy","car", "apple", "bill", "crow", "brown" };
// note the first non-dynamic select here was just because I don't think dynamic linq
// will support indexing a string like that and it's not an important detail anyway
var wordList = words.Select(w => new {FirstLetter = w[0], Word = w})
.GroupBy("new (FirstLetter)","Word");
foreach(IGrouping<object, dynamic> g in wordList)
{
Console.WriteLine("Words that being with {0}:",
g.Key.ToString().ToUpper());
foreach (var word in g)
Console.WriteLine(" " + word);
}
Console.ReadLine();
How would I get it to order the keys? At least part of the problem is that the dynamic GroupBy returns an IEnumerable. I thought it might be as easy as:
var wordList = words.Select(w => new {FirstLetter = w[0], Word = w})
.GroupBy("new (FirstLetter)","Word")
.OrderBy("Key");
But that gives me a System.ArgumentException (At least one object must implement IComparable.) when it hits the foreach loop.
My actual code in my project is a little more complicated and looks something like this:
var colGroup = row.GroupBy(string.Format("new({0})",
string.Join(",", c)), string.Format("new({0})",
string.Join(",", v)));
Where c is a list of strings that I need to group by and v is a list of strings that I need to select in each group.
Ok - this is one way to do it, but it might be a little to static to be useful. The problem is that I had this part:
.GroupBy("new (FirstLetter)","Word");
Using new because I can't use a value type as a key (I had another question about that: https://stackoverflow.com/a/26022002/1250301). When with the OrderBy("Key") part, the problem is that it doesn't have a way to compare those dynamic types. I could solve it like this:
var wordList = words.Select(w => new {FirstLetter = w[0].ToString(), Word = w})
.GroupBy("FirstLetter","Word")
.OrderBy("Key");
Making the key a string. Or like this:
var wordList = words.Select(w => new {FirstLetter = w[0], Word = w})
.GroupBy("new (FirstLetter as k)","Word")
.OrderBy("Key.k");
Making it order by something (a char) that is comparable.
I can make it work with my actual problem like this (but it's kind of ugly):
var colGroup = row.GroupBy(string.Format("new({0})", string.Join(",", c)),
string.Format("new({0})", string.Join(",", v)))
.OrderBy(string.Join(",", c.Select(ob => string.Format("Key.{0}", ob))));
I am not sure what you are trying to do, but is that syntax even compiling?
try:
string[] words = { "boy","car", "apple", "bill", "crow", "brown" };
var wordList = words.Select(w => new {FirstLetter = w[0], Word = w})
.GroupBy(x => x.FirstLetter, x => x.Word)
.OrderBy(x => x.Key);
I want to parse an SVG style attribute, which is just a delimited string, e.g.
"fill:#e2b126;stroke:#010101;stroke-width:0.3177;stroke-miterlimit:10"
into a Dictionary<string,string> so that I can perform some processing on it.
Here's what I have, which does the job, but I'd like to make it neater using a linq projection, just can't seem to get the syntax. I tried using .Select().ToDictionary etc, but no joy. Thanks:
string attributes = "fill:#e2b126;stroke:#010101;stroke-width:0.3177;stroke-miterlimit:10";
var pairs = attributes.Split(';').ToList();
var dic = new Dictionary<string, string>();
pairs.ForEach(p =>
{
var pair = p.Split(':');
dic.Add(pair[0], pair[1]);
});
foreach (var k in dic.Keys)
{
Console.WriteLine(k + " " + dic[k]);
}
Expected output:
fill #e2b126
stroke #010101
stroke-width 0.3177
stroke-miterlimit 10
Try the following
string attributes = "fill:#e2b126;stroke:#010101;stroke-width:0.3177;stroke-miterlimit:10";
var map = attributes
.Split(new []{';'}, StringSplitOptions.RemoveEmptyEntries)
.Select(x => x.Split(new []{':'}, StringSplitOptions.RemoveEmptyEntries))
.ToDictionary(p => p[0], p => p[1]);
Breakdown
The first Split call will return an array of String values where every entry is in the key:value format. The following Select call will convert every one of those entries into a string[] where the first element is the key and the second is the value. The ToDictionary call just expressly performs this mapping
I am trying to import values from a .txt file into my dictionary. The .txt file is formatted like this:
Donald Duck, 2010-04-03
And so on... there is 1 entry like that on each line. My problem comes when I try to add the split strings into the dictionary.
I am trying it like this: scoreList.Add(values[0], values[1]); But it says that names doesn't exist in the context. I hope someone can point me in the correct direction about this...
Thank you!
private void Form1_Load(object sender, EventArgs e)
{
Dictionary<string, DateTime> scoreList = new Dictionary<string, DateTime>();
string path = #"list.txt";
var query = (from line in File.ReadAllLines(path)
let values = line.Split(',')
select new { Key = values[0], Value = values[1] });
foreach (KeyValuePair<string, DateTime> pair in scoreList)
{
scoreList.Add(values[0], values[1]);
}
textBox1.Text = scoreList.Keys.ToString();
}
Your values variable are only in scope within the LINQ query. You need to enumerate the query result, and add the values to the dictionary:
foreach (var pair in query)
{
scoreList.Add(pair.Key, pair.Value);
}
That being said, LINQ features a ToDictionary extension method that can help you here. You could replace your loop with:
scoreList = query.ToDictionary(x => x.Key, x => x.Value);
Finally, for the types to be correct, you need to convert the Value to DateTimeusing, for instance, DateTime.Parse.
First you are doing it wrong, you should add item from list not values[0] and values[1] used in LINQ..
Dictionary<string, DateTime> scoreList = new Dictionary<string, DateTime>();
string path = #"list.txt";
var query = (from line in File.ReadAllLines(path)
let values = line.Split(',')
select new { Key = values[0], Value = values[1] });
foreach (var item in query) /*changed thing*/
{
scoreList.Add(item.Key, DateTime.Parse(item.Value)); /*changed thing*/
}
textBox1.Text = scoreList.Keys.ToString();
The immediate problem with the code is that values only exists in the query expression... your sequence has an element type which is an anonymous type with Key and Value properties.
The next problem is that you're then iterating over scoreList, which will be empty to start with... and there's also no indication of where you plan to convert from string to DateTime. Oh, and I'm not sure whether Dictionary<,>.Keys.ToString() will give you anything useful.
You can build the dictionary simply enough though:
var scoreList = File.ReadLines(path)
.Select(line => line.Split(','))
.ToDictionary(bits => bits[0], // name
bits => DateTime.ParseExact(bits[1], // date
"yyyy-MM-dd",
CultureInfo.InvariantCulture));
Note the use of DateTime.ParseExact instead of just DateTime.Parse - if you know the format of the data, you should use that information.
Is there a built-in function for converting a string array into a dictionary of strings or do you need to do a loop here?
Assuming you're using .NET 3.5, you can turn any sequence (i.e. IEnumerable<T>) into a dictionary:
var dictionary = sequence.ToDictionary(item => item.Key,
item => item.Value)
where Key and Value are the appropriate properties you want to act as the key and value. You can specify just one projection which is used for the key, if the item itself is the value you want.
So for example, if you wanted to map the upper case version of each string to the original, you could use:
var dictionary = strings.ToDictionary(x => x.ToUpper());
In your case, what do you want the keys and values to be?
If you actually just want a set (which you can check to see if it contains a particular string, for example), you can use:
var words = new HashSet<string>(listOfStrings);
You can use LINQ to do this, but the question that Andrew asks should be answered first (what are your keys and values):
using System.Linq;
string[] myArray = new[] { "A", "B", "C" };
myArray.ToDictionary(key => key, value => value);
The result is a dictionary like this:
A -> A
B -> B
C -> C
IMO, When we say an Array we are talking about a list of values that we can get a value with calling its index (value => array[index]), So a correct dictionary is a dictionary with a key of index.
And with thanks to #John Skeet, the proper way to achieve that is:
var dictionary = array
.Select((v, i) => new {Key = i, Value = v})
.ToDictionary(o => o.Key, o => o.Value);
Another way is to use an extension method like this:
public static Dictionary<int, T> ToDictionary<T>(this IEnumerable<T> array)
{
return array
.Select((v, i) => new {Key = i, Value = v})
.ToDictionary(o => o.Key, o => o.Value);
}
If you need a dictionary without values, you might need a HashSet:
var hashset = new HashSet<string>(stringsArray);
What do you mean?
A dictionary is a hash, where keys map to values.
What are your keys and what are your values?
foreach(var entry in myStringArray)
myDictionary.Add(????, entry);
I'll assume that the question has to do with arrays where the keys and values alternate. I ran into this problem when trying to convert redis protocol to a dictionary.
private Dictionary<T, T> ListToDictionary<T>(IEnumerable<T> a)
{
var keys = a.Where((s, i) => i % 2 == 0);
var values = a.Where((s, i) => i % 2 == 1);
return keys
.Zip(values, (k, v) => new KeyValuePair<T, T>(k, v))
.ToDictionary(kv => kv.Key, kv => kv.Value);
}
Dictionary<int, string> dictionaryTest = new Dictionary<int, string>();
for (int i = 0; i < testArray.Length; i++)
{
dictionaryTest.Add(i, testArray[i]);
}
foreach (KeyValuePair<int, string> item in dictionaryTest)
{
Console.WriteLine("Array Position {0} and Position Value {1}",item.Key,item.Value.ToString());
}
The Question is not very clear, but Yes you can convert a string to Dictionary provided the string is delimited with some characters to support Dictionary<Key,Value> pair
So if a string is like a=first;b=second;c=third;d=fourth you can split it first based on ; then on = to create a Dictionary<string,string> the below extension method does the same
public static Dictionary<string, string> ToDictionary(this string stringData, char propertyDelimiter = ';', char keyValueDelimiter = '=')
{
Dictionary<string, string> keyValuePairs = new Dictionary<string, string>();
Array.ForEach<string>(stringData.Split(propertyDelimiter), s =>
{
if(s != null && s.Length != 0)
keyValuePairs.Add(s.Split(keyValueDelimiter)[0], s.Split(keyValueDelimiter)[1]);
});
return keyValuePairs;
}
and can use it like
var myDictionary = "a=first;b=second;c=third;d=fourth".ToDictionary();
since the default parameter is ; & = for the extension method.
You can create a dictionary from an IEnumerable<T>, including an array, via:
var dictionary = myEnumerable.ToDictionary(element => element.Key,
element => element.Value)
where Key and Value are the key and value you want to store in each dictionary element. Available in .NET Framework 3.5+/.NET Core 1.0+/.NET 5.0+. Official documentation.
If you want the dictionary values to be the elements from the original enumerable:
var dictionary = myEnumerable.ToDictionary(element => element.Key)
If you only need high-performance set operations, you may be able to use:
var words = new HashSet<string>(listOfStrings);
In simple terms, the HashSet class can be thought of as a Dictionary<TKey,TValue> collection without values. Official documentation.
(Note that a 'sequence' in an entirely unrelated object.
Originally submitted an existing answer edit but it was rejected by the author so posting separately, including with links to the official Microsoft documentation.)