gnuplot documentation

66 gnuplot 4.3 60 PLOT
the automatic extension of the axis range upto the next tic mark.
BINARY DATA FILES:
Gnuplot can read binary data files. However, adequate information about details of the file format
must be given on the command line or extracted from the file itself for a supported binary filetype. In
particular, there are two structures for binary files, a matrix binary format and a general binary format.
The matrix binary format contains a two dimensional array of 32 bit IEEE float values with an additional
column and row of coordinate values. As with ASCII matrix, in the using list, repetition of the coordinate
row constitutes column 1, repetition of the coordinate column constitutes column 2, and the array of
values constitutes column 3.
The general binary format contains an arbitrary number of columns for which information must be
specified at the command line. For example, array, record, format and using can indicate the size,
format and dimension of data. There are a variety of useful commands for skipping file headers and
changing endianess. There are a set of commands for positioning and translating data since often
coordinates are not part of the file when uniform sampling is inherent in the data. Different from matrix
binary or ASCII, general binary does not treat the generated columns as 1, 2 or 3 in the using list.
Rather, column 1 begins with column 1 of the file, or as specified in the format list.
There are global default settings for the various binary options which may be set using the same syntax
as the options when used as part of the (s)plot binary ... command. This syntax is
set datafile binary .... The general rule is that common command-line specified parameters override
file-extracted parameters which override default parameters.
Matrix binary is the default binary format when no keywords specific to general binary are given, i.e.,
array, record, format, filetype.
General binary data can be entered at the command line via the special file name ’-’. However, this is
intended for use through a pipe where programs can exchange binary data, not for keyboards. There is
no "end of record" character for binary data. Gnuplot continues reading from a pipe until it has read
the number of points declared in the array qualifier.
See datafile binary (p. 66) for more details.
60.2.1 Binary
The binary keyword allows a data file to be binary as opposed to ASCII. There are two formats for
binary–matrix binary and general binary. Matrix binary is a fixed format in which data appears in a 2D
array with an extra row and column for coordinate values. General binary is a flexible format for which
details about the file must be given at the command line.
See binary matrix (p. 151) or binary general (p. 66) for more details.
60.2.2 Binary general
General binary data in which format information is not necessarily part of the file can be read by giving
further details about the file format at the command line. Although the syntax is slightly arcane to
the casual user, general binary is particularly useful for application programs using gnuplot and sending
large amounts of data.
Syntax:
plot ’’ {binary } ...
splot ’’ {binary } ...
General binary format is activated by keywords in pertaining to information about file
structure, i.e., array, record, format or filetype. Otherwise, matrix binary format is assumed. (See
binary matrix (p. 151) for more details.)
There are some standard file types that may be read for which details about the binary format may
be extracted automatically. (Type show datafile binary at the command line for a list.) Otherwise,
details must be specified at the command line or set in the defaults. Keywords are described below.