Special-filenames

A special filename of '-' specifies that the data are inline; i.e., they follow the command. Only the data follow the command; plot options like filters, titles, and line styles remain on the plot command line. This is similar to 5#55#5 in unix shell script, and $DECK in VMS DCL. The data are entered as though they are being read from a file, one data point per record. The letter "e" at the start of the first column terminates data entry. The using option can be applied to these data -- using it to filter them through a function might make sense, but selecting columns probably doesn't!

'-' is intended for situations where it is useful to have data and commands together, e.g., when gnuplot is run as a sub-process of some front-end application. Some of the demos, for example, might use this feature. While plot options such as index and every are recognized, their use forces you to enter data that won't be used. For example, while

     plot '-' index 0, '-' index 1
     2
     4
     6

     10
     12
     14
     e
     2
     4
     6

     10
     12
     14
     e

does indeed work,

     plot '-', '-'
     2
     4
     6
     e
     10
     12
     14
     e

is a lot easier to type.

If you use '-' with replot, you may need to enter the data more than once (see replot (p. )).

A blank filename ('') specifies that the previous filename should be reused. This can be useful with things like

     plot 'a/very/long/filename' using 1:2, '' using 1:3, '' using 1:4

(If you use both '-' and '' on the same plot command, you'll need to have two sets of inline data, as in the example above.)

On some computer systems with a popen function (Unix), the datafile can be piped through a shell command by starting the file name with a '5#5'. For example,

     pop(x) = 103*exp(-x/10)
     plot "< awk '{print $1-1965, $2}' population.dat", pop(x)

would plot the same information as the first population example but with years since 1965 as the x axis. If you want to execute this example, you have to delete all comments from the data file above or substitute the following command for the first part of the command above (the part up to the comma):

     plot "< awk '$0 !~ /^#/ {print $1-1965, $2}' population.dat"

While this approach is most flexible, it is possible to achieve simple filtering with the using or thru keywords.