Multidimensional array vs dictionary performance

I am needing to do a lookup on a large bool set using x,y,z coordinates(integers only). I am trying to determine if a block is traversable at x,y,z location.

Currently I am using an array bool[,,]. However, this is not very flexible, and the size quickly gets massive for a decent sized map.

I thought a dictionary that only holds the true values would be much more flexible and less memory hungry. I created a struct Vector3Int to hold the x,y,z values and use as a dictionary key. Dictionary looks like Dictionary<Vector3Int, bool>.

However, doing Dictionary lookups with this key appears to be 20-100 times slower than the array lookups with x,y,z integers.

Is there a faster/better way to do this? I am using the lookups for pathfinding, so the lookup needs to be quite fast as there may be hundreds/thousands of lookups for a single path.

Vector3Int code:

public struct Vector3Int { public int x,y,z; public Vector3Int(int x, int y, int z) { this.x =x; this.y=y; this.z=z; } //checks for equality public static bool operator ==(Vector3Int a, Vector3Int b) { return a.x==b.x && a.y ==b.y && a.z ==b.z; } public override bool Equals(object obj) { return obj is Vector3Int && this == (Vector3Int)obj; } public override int GetHashCode () { return x.GetHashCode() ^ y.GetHashCode() ^ z.GetHashCode(); } //checks the two vectors for non-equality public static bool operator !=(Vector3Int a, Vector3Int b) { return !(a==b); } } 

Array lookup:

bool[,,] worldWalkable= new bool[1000,1000,1000]; public bool CheckWalkable(int x, int y, int z) { return worldWalkable[x,y,z]; } 

Vs Dictionary Lookup:

Dictionary<Vector3Int, bool> worldTraversable = new Dictionary<Vector3Int, bool>(); public bool CheckTraversable(Vector3Int block) { bool tempBool; worldTraversable.TryGetValue(block, tempBool); return tempBool; } 

Test code:

using UnityEngine; using System.Collections; using System.Collections.Generic; public class SpeedTest : MonoBehaviour { Dictionary<Vector3Int, bool> testDict; bool[,,] testArray; // Use this for initialization void Start () { InitializeContainers(); RunTest(); } void InitializeContainers() { testDict= new Dictionary<Vector3Int, bool>(1000); for(int i=0; i<10; i++) { for(int j=0; j<10; j++) { for(int k=0; k<10; k++) { testDict[new Vector3Int(i,j,k)]=true; } } } testArray=new bool[10,10,10]; } void RunTest() { bool tempBool; float timer1, timer2; timer1=Time.realtimeSinceStartup; for(int i=0; i<10; i++) { for(int j=0; j<10; j++) { for(int k=0; k<10; k++) { tempBool= testDict[new Vector3Int(i,j,k)]; } } } timer2=Time.realtimeSinceStartup; Debug.Log("Dictionary completion time: "+(timer2-timer1)*1000+"ms"); timer1=Time.realtimeSinceStartup; for(int i=0; i<10; i++) { for(int j=0; j<10; j++) { for(int k=0; k<10; k++) { tempBool=testArray[i,j,k]; } } } timer2=Time.realtimeSinceStartup; Debug.Log("Array completion time: "+(timer2-timer1)*1000+"ms"); } } 

Edit: Revised struct that fixes the problem:

using UnityEngine; using System.Collections; using System; using System.Collections.Generic; //makes a Vector3 of integers public struct Vector3Int : IEquatable<Vector3Int> { public int x,y,z; public Vector3Int(int x, int y, int z) { this.x =x; this.y=y; this.z=z; } public bool Equals(Vector3Int other) { return other.x==this.x && other.y==this.y && other.z==this.z; } public static bool operator ==(Vector3Int a, Vector3Int b) { return a.Equals(b); } public override bool Equals(object obj) { if(obj==null || !(obj is Vector3Int)) return false; return Equals((Vector3Int)obj); } public override int GetHashCode () { return x ^ (y<<10) ^ (z<<10); } public override string ToString () { return string.Format ("("+x+", "+y+", "+z+")"); } public static bool operator !=(Vector3Int a, Vector3Int b) { return !(a==b); } } 

The issue was boxing/unboxing like Alexei suggested. Used the directions from this link to fix the issue.