gnuplot command every on row only - csv

Question

I have a matrix listed in a .csv file of approximately 0.6 mio datapoints I would like to visualize in a 3d plot. Since my computer showed troubles with the amount of data I evolved the command line from:
splot "file.csv" matrix w pm3d
to
splot "file.csv" matrix every 5::50::3000 w pm3d
My intention was to only plot from row 50 to 3000 using only every 5th row. A row contains 100 columns btw. The command however cut the first 50 rows and columns, using every 5th row and column and ended in with line 3500.
How do I use the every command on my rows only?
I also tried to combine the using command with the every command in order to define my row with the every command but I couldn't get it to work properly.

Answer 1

Short answer: Use
splot "file.csv" matrix every :5::50::3000 w pm3d
Long answer: The description of the every option is:
plot ’file’ every {<point_incr>}
{:{<block_incr>}
{:{<start_point>}
{:{<start_block>}
{:{<end_point>}
{:<end_block>}}}}}
The description of point and block refers to the usual data file structure, where two data blocks are separated by an empty line.
When using the matrix data format, replace point by column and block by row. That means, that every 1:1 selects all points, every 2:1 selects every second column and every row, every 1:2 (or every :2) selects every column and every second row.
Just use a simple data file
0 0 0 0 0 0
file0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
and test:
splot 'file' matrix with lines, '' every :2