In the following Gnuplot script, I want to extract values from a specific table. This works fine for columns that contain numbers but I cannot extract the path from the column "Measure:volume". What needs to be changed to solve this problem?
reset
set datafile missing "NaN"
set datafile columnheader
$Data << EOD
Measure:volume lh_01 rh_01
sub_001/2001476309_t1 7030.26 7353.44
sub_002/2026003745_t1 7652.64 8566.62
sub_003/0119972330_t1 6938.74 7489.41
sub_004/2022130250_t1 6619.97 6224.74
sub_005/2105171757_t1 7472.23 8635.48
sub_006/2060302238_t1 6612.52 7347.70
sub_007/2021110417_t1 7049.64 7137.09
sub_008/0152544707_t1 8327.11 8745.67
sub_009/0219080602_t1 7924.66 8694.33
sub_010/2018143733_t1 7605.58 8072.01
EOD
path_column = "Measure:volume"
left = "lh_01"
right = "rh_01"
set table $Temp
plot $Data using path_column:left:right with table
unset table
print $Temp
### End of script
The result looks like this:
gnuplot> load "test_plot_data.gp"
nan 7030.26 7353.44
nan 7652.64 8566.62
nan 6938.74 7489.41
nan 6619.97 6224.74
nan 7472.23 8635.48
nan 6612.52 7347.7
nan 7049.64 7137.09
nan 8327.11 8745.67
nan 7924.66 8694.33
nan 7605.58 8072.01
gnuplot>
Ok, now I see what you meant. Since the column withthe header "Measure:volume" is a column with string values, of course you have to use stringcolumn() or shorter strcol() (check help strcol).
Hence, the following should do the job. Don't forget the parantheses around (strcol(path_column)).
path_column = "Measure:volume"
plot $Data u (strcol(path_column)):left:right with table