2

I am using the new feature introduced in Gnuplot 5.0 to create a datablock and plot it using the following code.

#set term wxt enhanced 0 font 'Helvetica,' noraise

# set labels
set title 'Sample Points'
set xlabel 'X pos' offset -5
set ylabel 'Y pos' offset 3
set zlabel 'Speed' offset -2 rotate left
set key outside right top box

set grid
set border 4095
set xtics 20
set ytics 20

set style line 1 pointtype 7 pointsize 1 lc rgb 'red'
set style line 2 pointtype 7 pointsize 1 lc rgb 'green'
set style line 3 pointtype 7 pointsize 1 lc rgb 'blue'

# loop begin

$data << EOD 
821.328349 898.350000 18.887529 0 
901.650000 821.328349 18.887529 1 
898.350000 978.671651 18.887529 2 
978.671651 901.650000 18.887529 3 
823.181732 898.350000 18.533830 0 
901.650000 823.181732 18.533830 1 
898.350000 976.818268 18.533830 2 
976.818268 901.650000 18.533830 3 
824.999809 898.350000 18.180776 0 
901.650000 824.999809 18.180776 1 
898.350000 975.000191 18.180776 2 
975.000191 901.650000 18.180776 3 
826.782868 898.350000 17.830582 0 
901.650000 826.782868 17.830582 1 
898.350000 973.217132 17.830582 2 
973.217132 901.650000 17.830582 3 
828.531204 898.350000 17.483360 0 
901.650000 828.531204 17.483360 1 
898.350000 971.468796 17.483360 2 
971.468796 901.650000 17.483360 3 


830.244850 898.350000 17.136468 0 
901.650000 830.244850 17.136468 1 
898.350000 969.755150 17.136468 2 
969.755150 901.650000 17.136468 3 
831.924084 898.350000 16.792338 0 
901.650000 831.924084 16.792338 1 
898.350000 968.075916 16.792338 2 
968.075916 901.650000 16.792338 3 
833.569227 898.350000 16.451429 0 
901.650000 833.569227 16.451429 1 
898.350000 966.430773 16.451429 2 
966.430773 901.650000 16.451429 3 
835.180379 898.350000 16.111523 0 
901.650000 835.180379 16.111523 1 
898.350000 964.819621 16.111523 2 
964.819621 901.650000 16.111523 3 
836.757776 898.350000 15.773971 0 
901.650000 836.757776 15.773971 1 
898.350000 963.242224 15.773971 2 
963.242224 901.650000 15.773971 3 


838.301768 898.350000 15.439919 0 
901.650000 838.301768 15.439919 1 
898.350000 961.698232 15.439919 2 
961.698232 901.650000 15.439919 3 
839.812485 898.350000 15.107162 0 
901.650000 839.812485 15.107162 1 
898.350000 960.187515 15.107162 2 
960.187515 901.650000 15.107162 3 
841.290161 898.350000 14.776766 0 
901.650000 841.290161 14.776766 1 
898.350000 958.709839 14.776766 2 
958.709839 901.650000 14.776766 3 
842.735180 898.350000 14.450189 0 
901.650000 842.735180 14.450189 1 
898.350000 957.264820 14.450189 2 
957.264820 901.650000 14.450189 3 
844.147653 898.350000 14.124734 0 
901.650000 844.147653 14.124734 1 
898.350000 955.852347 14.124734 2 
955.852347 901.650000 14.124734 3 


845.527869 898.350000 13.802154 0 
901.650000 845.527869 13.802154 1 
898.350000 954.472131 13.802154 2 
954.472131 901.650000 13.802154 3 
846.876245 898.350000 13.483757 0 
901.650000 846.876245 13.483757 1 
898.350000 953.123755 13.483757 2 
953.123755 901.650000 13.483757 3 
848.192819 898.350000 13.165744 0 
901.650000 848.192819 13.165744 1 
898.350000 951.807181 13.165744 2 
951.807181 901.650000 13.165744 3 
849.477992 898.350000 12.851735 0 
901.650000 849.477992 12.851735 1 
898.350000 950.522008 12.851735 2 
950.522008 901.650000 12.851735 3 
850.732123 898.350000 12.541306 0 
901.650000 850.732123 12.541306 1 
898.350000 949.267877 12.541306 2 
949.267877 901.650000 12.541306 3 


851.955313 898.350000 12.231900 0 
901.650000 851.955313 12.231900 1 
898.350000 948.044687 12.231900 2 
948.044687 901.650000 12.231900 3 
853.148046 898.350000 11.927332 0 
901.650000 853.148046 11.927332 1 
898.350000 946.851954 11.927332 2 
946.851954 901.650000 11.927332 3 
854.310507 898.350000 11.624608 0 
901.650000 854.310507 11.624608 1 
898.350000 945.689493 11.624608 2 
945.689493 901.650000 11.624608 3 
855.443020 898.350000 11.325128 0 
901.650000 855.443020 11.325128 1 
898.350000 944.556980 11.325128 2 
944.556980 901.650000 11.325128 3 
856.546040 898.350000 11.030203 0 
901.650000 856.546040 11.030203 1 
898.350000 943.453960 11.030203 2 
943.453960 901.650000 11.030203 3 


857.619649 898.350000 10.736086 0 
901.650000 857.619649 10.736086 1 
898.350000 942.380351 10.736086 2 
942.380351 901.650000 10.736086 3 
858.664411 898.350000 10.447624 0 
901.650000 858.664411 10.447624 1 
898.350000 941.335589 10.447624 2 
941.335589 901.650000 10.447624 3 
859.680471 898.350000 10.160601 0 
901.650000 859.680471 10.160601 1 
898.350000 940.319529 10.160601 2 
940.319529 901.650000 10.160601 3 
860.668283 898.350000 9.878115 0 
901.650000 860.668283 9.878115 1 
898.350000 939.331717 9.878115 2 
939.331717 901.650000 9.878115 3 
861.628190 898.350000 9.599073 0 
901.650000 861.628190 9.599073 1 
898.350000 938.371810 9.599073 2 
938.371810 901.650000 9.599073 3 


862.560481 898.350000 9.322910 0 
901.650000 862.560481 9.322910 1 
898.350000 937.439519 9.322910 2 
937.439519 901.650000 9.322910 3 
863.465671 898.350000 9.051895 0 
901.650000 863.465671 9.051895 1 
898.350000 936.534329 9.051895 2 
936.534329 901.650000 9.051895 3 
864.343914 898.350000 8.782434 0 
901.650000 864.343914 8.782434 1 
898.350000 935.656086 8.782434 2 
935.656086 901.650000 8.782434 3 
865.195863 898.350000 8.519487 0 
901.650000 865.195863 8.519487 1 
898.350000 934.804137 8.519487 2 
934.804137 901.650000 8.519487 3 
866.021577 898.350000 8.257141 0 
901.650000 866.021577 8.257141 1 
898.350000 933.978423 8.257141 2 
933.978423 901.650000 8.257141 3 


866.821806 898.350000 8.002291 0 
901.650000 866.821806 8.002291 1 
898.350000 933.178194 8.002291 2 
933.178194 901.650000 8.002291 3 
867.596557 898.350000 7.747514 0 
901.650000 867.596557 7.747514 1 
898.350000 932.403443 7.747514 2 
932.403443 901.650000 7.747514 3 
868.346635 898.350000 7.500778 0 
901.650000 868.346635 7.500778 1 
898.350000 931.653365 7.500778 2 
931.653365 901.650000 7.500778 3 
869.072042 898.350000 7.254067 0 
901.650000 869.072042 7.254067 1 
898.350000 930.927958 7.254067 2 
930.927958 901.650000 7.254067 3 
869.773586 898.350000 7.015447 0 
901.650000 869.773586 7.015447 1 
898.350000 930.226414 7.015447 2 
930.226414 901.650000 7.015447 3 
EOD

splot '$data' index 0 using 1:2:3 with points ls 1 title 'class 1',\
      ''      index 1 using 1:2:3 with points ls 2 title 'class 2',\
      ''      index 2 using 1:2:3 with points ls 3 title 'class 3',\
      ''      index 3 using 1:2:3 with points ls 1 title 'class 4',\
      ''      index 4 using 1:2:3 with points ls 2 title 'class 5',\
      ''      index 5 using 1:2:3 with points ls 3 title 'class 6',\
      ''      index 6 using 1:2:3 with points ls 1 title 'class 7',\
      ''      index 7 using 1:2:3 with points ls 2 title 'class 8'

# loop end

The whole datablock section and splot command are in a loop. Every time that I get a new point, I make a new datablock and then splot it. This approach is inefficient and I am looking for a way to only append the new point to the existing data without the need to re-construct the whole datablock in the script. How can I achieve that?

Edit: I don't want to use an external file.

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1 Answer 1

Reset to default
3

You can print to a datablock, both overwriting or appending it. Suppose that I use

$k << EOD
1 2
2 3
4 5
EOD

To create datablock $k. Now I wish to add a new line 5 6 to this. I first set the print output to the datablock, and then print my new line, setting the print command back when I am done.

set print $k append
print "5 6"
set print

Now my datablock $k looks like

1 2
2 3
4 5
5 6

I can even create multiple blocks by printing blank lines. For example, if I wish to use my existing $k to create a new $l with two blocks (no append, as I don't need to append to an existing block), I can do

set print $l
print $k
print ""
print $k
set print

This sets up a new block $l with

1 2
2 3
4 5
5 6


1 2
2 3
4 5
5 6

Unfortunately, this will insert a blank line after each copy of $k (as the print command adds a newline deliminator, and the block already has one), so this won't work if you need to keep repeating the same base and add a few extra lines to each block. Storing the data in a string can allow that.

bse = "1 2\n2 3\n4 5"
set print $l
print bse
print "5 6"
print ""
print ""
print bse
print "7 8"
set print

This will produce

1 2
2 3
4 5
5 6


1 2
2 3
4 5
7 8
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