The scan operator produces a result array that is equivalent to a stored array. That is, scan reads a stored array.

Synopsis

scan(stored_array);

Inputs

stored_array:  An array that was previously created and stored in SciDB.

Summary

The scan operator reads a stored array from disk. The scan operator's output is an array with the same content as stored_array.  The scan operator is most useful for displaying a stored array on stdout from the AFL language.

Example

To create, build, scan, and store an array, do the following:

1. Create a 3×3 array called m3x3_A:

   AFL% CREATE ARRAY m3x3_A <val_A:double>[i=0:2; j=0:2];

   
   The output is:

   Query was executed successfully

2. Put values of 0–8 into the m3x3_A array:

    AFL% store(build(m3x3_A,i*3+j),m3x3_A);

   
   The output is:

   {i,j} val_A
   {0,0} 0
   {0,1} 1
   {0,2} 2
   {1,0} 3
   {1,1} 4
   {1,2} 5
   {2,0} 6
   {2,1} 7
   {2,2} 8

   
   

3. Create the m3x3_B array

   AFL% CREATE ARRAY m3x3_B <val_B:double>[i=0:2; j=0:2];

   
   The output is:

   Query was executed successfully

4. Use scan to display m3x3_A array: 

   AFL% scan(m3x3_A);

   
   The output is:

   {i,j} val_A
   {0,0} 0
   {0,1} 1
   {0,2} 2
   {1,0} 3
   {1,1} 4
   {1,2} 5
   {2,0} 6
   {2,1} 7
   {2,2} 8

5. Use scan to display m3x3_B array:
   

   AFL% scan(m3x3_B);

   
   The output is:

   {i,j} val_B

   
   

6. Store the scan output of array m3x3_A into the m3x3_B array:

   AFL% store(scan(m3x3_A), m3x3_B);

   
   The output is:

   {i,j} val_B
   {0,0} 0
   {0,1} 1
   {0,2} 2
   {1,0} 3
   {1,1} 4
   {1,2} 5
   {2,0} 6
   {2,1} 7
   {2,2} 8

7. Scan m3x3_B to ensure it has the expected data

   AFL% scan(m3x3_B);

   
   The output is:

   {i,j} val_B
   {0,0} 0
   {0,1} 1
   {0,2} 2
   {1,0} 3
   {1,1} 4
   {1,2} 5
   {2,0} 6
   {2,1} 7
   {2,2} 8

8. Remove the m3x3_A array:

   AFL% remove(m3x3_A);

   
   The output is:

   Query was executed successfully

9. Remove the m3x3_B array:

   AFL% remove(m3x3_B);

   
   The output is:

   Query was executed successfully