2 added 16 characters in body edited Mar 27 '13 at 15:25 Szabolcs 172k1818 gold badges468468 silver badges10021002 bronze badges If you would like to use ArrayPlot or MatrixPlot, first you need to convert your data into a matrix format. You can use SparseArray for this. Here's an example: MatrixPlot[SparseArray[{#1/25 + 1, #2} -> #3 & @@@ a]]  Make sure that the matrix indexes will start from 1, not from 0. I needed to add 1 to the first index for this. I also rescaled the first index by 25 (a random choice) in order not to get a 100 by 2 matrix which would not be that useful to look at. The unspecified elements are taken to be 0 here, but you can specify an alternative, or rescale by 50 so you won't have any empty elements. If you would like to use ArrayPlot, first you need to convert your data into a matrix format. You can use SparseArray for this. Here's an example: MatrixPlot[SparseArray[{#1/25 + 1, #2} -> #3 & @@@ a]]  Make sure that the matrix indexes will start from 1, not from 0. I needed to add 1 to the first index for this. I also rescaled the first index by 25 (a random choice) in order not to get a 100 by 2 matrix which would not be that useful to look at. The unspecified elements are taken to be 0 here, but you can specify an alternative, or rescale by 50 so you won't have any empty elements. If you would like to use ArrayPlot or MatrixPlot, first you need to convert your data into a matrix format. You can use SparseArray for this. Here's an example: MatrixPlot[SparseArray[{#1/25 + 1, #2} -> #3 & @@@ a]]  Make sure that the matrix indexes will start from 1, not from 0. I needed to add 1 to the first index for this. I also rescaled the first index by 25 (a random choice) in order not to get a 100 by 2 matrix which would not be that useful to look at. The unspecified elements are taken to be 0 here, but you can specify an alternative, or rescale by 50 so you won't have any empty elements. 1 answered Mar 27 '13 at 14:22 Szabolcs 172k1818 gold badges468468 silver badges10021002 bronze badges If you would like to use ArrayPlot, first you need to convert your data into a matrix format. You can use SparseArray for this. Here's an example: MatrixPlot[SparseArray[{#1/25 + 1, #2} -> #3 & @@@ a]]  Make sure that the matrix indexes will start from 1, not from 0. I needed to add 1 to the first index for this. I also rescaled the first index by 25 (a random choice) in order not to get a 100 by 2 matrix which would not be that useful to look at. The unspecified elements are taken to be 0 here, but you can specify an alternative, or rescale by 50 so you won't have any empty elements.