I have a n-by-3 array I wish to convert to a Dictionary<string,string[]>
where the first column is the key and the rest of the column as an array for the value.
For example:
Key = arr[0,0], Value = new string[2] {arr[0,1], arr[0,2]}.
I'm aware of ToDictionary
but I don't know how to set the value part.
arr.ToDictionary(x=>arr[x,0],x=>new string[2]{arr[x,1],arr[x,2]});
//This doesn't work!!!
How can I set it up correctly?
Multidimensional arrays are a continuous block of memory, so you kind of have to treat them like a single array. Try this:
var dict = arr.Cast<string>()
.Select((s, i) => new { s, i })
.GroupBy(s => s.i / arr.GetLength(1))
.ToDictionary(
g => g.First().s,
g => g.Skip(1).Select(i => i.s).ToArray()
);
With explanations:
// First, cast it to an IEnumerable<string>
var dict = arr.Cast<string>()
// Use the Select overload that lets us get the index of the element,
// And we capture the element's index (i), along with the element itself (s)
// and put them together into an anonymous type [1]
.Select((s, i) => new { s, i })
// .GetLength(dimension) is a method on multidimensional arrays to
// get the length of a given dimension (pretty self-explanatory)
// In this case, we want the second dimension, or how wide each
// row is: [x,y] <- we want y
// Divide the element index (s.i) by that length to get the row index
// for that element
.GroupBy(s => s.i / arr.GetLength(1))
// Now we have an Grouping<int, IEnumerable<anonymous{string,int}>>
.ToDictionary(
// We don't care about the key, since it's the row index, what we want
// is the string value (the `s` property) from first element in the row
g => g.First().s,
// For the value, we want to skip the first element, and extract
// the string values (the `s` property), and then convert to an array
g => g.Skip(1).Select(i => i.s).ToArray()
);
[1]: See here for documentation on anonymous types.
This is the simplest approach I can come up with:
var arr = new int[4, 3]
{
{ 1, 2, 3 },
{ 3, 5, 7 },
{ 5, 8, 11 },
{ 7, 11, 15 },
};
var dict = arr.Cast<int>().Buffer(3).ToDictionary(x => x[0], x => x.Skip(1).ToArray());
That gives me:
You just need to NuGet "System.Interactive" to get the Buffer
operator.
Or use this implementation:
public static IEnumerable<T[]> Buffer<T>(this IEnumerable<T> source, int count)
=>
source
.Select((t, i) => new { t, i })
.GroupBy(x => x.i / count)
.Select(x => x.Select(y => y.t).ToArray());
I guess your approach was right ,my only doubt is that your array is static or not?
arr.Select((value, index) => new { value, index }) .ToDictionary(x => x.index, x => new string[2]{x.value[x.index][1],x.value[x.index][2]}));
Note: I couldn't execute and check the code ! Sorry.
Sometimes not using linq is easier to read and faster:
var dict = new Dictionary<string, string[]>();
for (int i = 0; i < arr.GetLength(0); i++)
dict[arr[i, 0]] = new string[] { arr[i, 1], arr[i, 2] };
But when you feel like you REALLY need to use linq:
Enumerable.Range(0, arr.GetLength(0))
.ToDictionary(i => arr[i, 0], i => new string[] {arr[i, 1], arr[i, 2]});
I had done using Integer. Please Change for your requirements.
public static void Main()
{
int row=0 , col=0;
int[,] array = new int[,]
{
{ 1, 2, 3 },
{ 4, 5, 6 },
{ 7, 8, 9 },
{ 10, 11, 12 }
};
int flag=0;
for (int i = 0; i < array.Rank; i++)
{
if(flag==0)
{
row= array.GetLength(i);
flag=1;
}
else
{
col= array.GetLength(i);
}
}
Dictionary<int,int[,]> dictionary = new Dictionary<int, int[,]>();
for(int i=0;i<row;i++)
{
dictionary.Add(array[i,0],new int[, ]{{array[i,1]},{array[i,2]}});
}
Console.WriteLine(dictionary[4].GetValue(0,0));
}
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