GNUPlot Manual

40 gnuplot 4.0 28 PLOT
In the discussion a "point" is a datum defined by a single record in the file; "block" here will mean the
same thing as "datablock" (see glossary (p. 23)).
Syntax:
plot ’file’ every {}
{:{}
{:{}
{:{}
{:{}
{:}}}}}
The data points to be plotted are selected according to a loop from to
with increment and the blocks according to a loop from to
with increment .
The first datum in each block is numbered ’0’, as is the first block in the file.
Note that records containing unplottable information are counted.
Any of the numbers can be omitted; the increments default to unity, the start values to the first point
or block, and the end values to the last point or block. If every is not specified, all points in all lines
are plotted.
Examples:
every :::3::3
every :::::9
every 2:2
every ::5::15
# selects just the fourth block (’0’ is first)
# selects the first 10 blocks
# selects every other point in every other block
# selects points 5 through 15 in each block
See simple plot demos (simple.dem) , Non-parametric splot demos , and Parametric splot
demos .
28.1.2 Example datafile
This example plots the data in the file "population.dat" and a theoretical curve:
pop(x) = 103*exp((1965-x)/10)
plot [1960:1990] ’population.dat’, pop(x)
The file "population.dat" might contain:
# Gnu population in Antarctica since 1965
1965 103
1970 55
1975 34
1980 24
1985 10
28.1.3 Index
The index keyword allows only some of the data sets in a multi-data-set file to be plotted.
Syntax:
plot ’file’ index {{:}:}
Data sets are separated by pairs of blank records. index selects only set ; index :
selects sets in the range to ; and index :: selects indices , +,
+2, etc., but stopping at . Following C indexing, the index 0 is assigned to the first data
set in the file. Specifying too large an index results in an error message. If index is not specified, all
sets are plotted as a single data set.
Example:
plot ’file’ index 4:5
splot with indices demo.