# $Id: gp_unix.py,v 2.3 2001/01/07 21:35:13 mhagger Exp $ # Copyright (C) 1998,1999 Michael Haggerty # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation; either version 2 of the License, or # (at your option) any later version. This program is distributed in # the hope that it will be useful, but WITHOUT ANY WARRANTY; without # even the implied warranty of MERCHANTABILITY or FITNESS FOR A # PARTICULAR PURPOSE. See the GNU General Public License for more # details; it is available at , # or by writing to the Free Software Foundation, Inc., 59 Temple Place # - Suite 330, Boston, MA 02111-1307, USA. """gp_unix -- an interface to gnuplot used for unix platforms. This file implements a low-level interface to a gnuplot program for a unix platform (actually it is used for any non-Windows, non-Mac system). This file should be imported through gp.py, which in turn should be imported via 'import Gnuplot' rather than these low-level interfaces. """ __cvs_version__ = '$Revision: 2.3 $' # ############ Configuration variables: ################################ class GnuplotOpts: """The configuration options for gnuplot on generic platforms. Store the options in a class to make them easy to import and modify en masse. If you want to modify the options from the command line or within a running program, do something like the following:: import Gnuplot Gnuplot.GnuplotOpts.gnuplot_command = '/bin/mygnuplot' """ # Command to start up the gnuplot program. If your version of # gnuplot is run otherwise, specify the correct command here. You # could also specify a full path or append command-line options # here if you wish. gnuplot_command = 'gnuplot' # Recent versions of gnuplot (at least for Xwindows) allow a # `-persist' command-line option when starting up gnuplot. When # this option is specified, graph windows remain on the screen # even after you quit gnuplot (type `q' in the window to close # it). This can be handy but unfortunately it is not supported by # older versions of gnuplot. The following configuration variable # specifies whether the user's version of gnuplot recognizes this # option or not. You can set this variable to 1 (supports # -persist) or 0 (doesn't support) yourself; if you leave it with # the value None then the first time you create a Gnuplot object # it will try to detect automatically whether your version accepts # this option. recognizes_persist = None # test automatically on first use # What should be the default if the persist option is not # specified explicitly? prefer_persist = 0 # Recent versions of gnuplot allow you to specify a `binary' # option to the splot command for grid data, which means that the # data file is to be read in binary format. This option saves # substantial time writing and reading the file, and can also save # substantial disk space and therefore it is the default for that # type of plot. But if you have an older version of gnuplot (or # you prefer text format) you can disable the binary option in # either of two ways: (a) set the following variable to 0; or (b) # pass `binary=0' to the GridData constructor. (Note that the # demo uses binary=0 to maximize portability.) recognizes_binary_splot = 1 # Data can be passed to gnuplot through a temporary file or as # inline data (i.e., the filename is set to '-' and the data is # entered into the gnuplot interpreter followed by 'e'). If # prefer_inline_data is true, then use the inline method as # default whenever it is supported. This should be fast but will # use more memory since currently the inline data is put into a # big string when the PlotItem is created. prefer_inline_data = 0 # After a hardcopy is produced, we have to set the terminal type # back to `on screen' using gnuplot's `set terminal' command. The # following is the usual setting for Xwindows. If it is wrong, # change the following line to select the terminal type you prefer # to use for on-screen work. default_term = 'x11' # Gnuplot can plot to a printer by using "set output '| ...'" # where ... is the name of a program that sends its stdin to a # printer, or by "set output 'printer_device', where # 'printer_device is the name of a file-like interface to the # printer. On my machine the appropriate program is `lpr', as set # below. On your computer it may be something different (like # `lp'); you can set that by changing the variable below. You can # also add options to the print command if needed. default_lpr = '| lpr' # Enhanced postscript is an option to the postscript terminal # driver that requests enhanced treatment of strings (for example, # font changes, superscripts, and subscripts). Set to 1 to enable # or 0 to disable. If you have a version of gnuplot earlier than # 3.7, you should set this to None (*not* 0!) so that the option # is not used at all. prefer_enhanced_postscript = 1 # ############ End of configuration options ############################ from os import popen def test_persist(): """Determine whether gnuplot recognizes the option '-persist'. If the configuration variable 'recognizes_persist' is set (i.e., to something other than 'None'), return that value. Otherwise, try to determine whether the installed version of gnuplot recognizes the -persist option. (If it doesn't, it should emit an error message with '-persist' in the first line.) Then set 'recognizes_persist' accordingly for future reference. """ if GnuplotOpts.recognizes_persist is None: import string g = popen('echo | %s -persist 2>&1' % GnuplotOpts.gnuplot_command, 'r') response = g.readlines() g.close() GnuplotOpts.recognizes_persist = ( (not response) or (string.find(response[0], '-persist') == -1)) return GnuplotOpts.recognizes_persist class GnuplotProcess: """Unsophisticated interface to a running gnuplot program. This represents a running gnuplot program and the means to communicate with it at a primitive level (i.e., pass it commands or data). When the object is destroyed, the gnuplot program exits (unless the 'persist' option was set). The communication is one-way; gnuplot's text output just goes to stdout with no attempt to check it for error messages. Members: 'gnuplot' -- the pipe to the gnuplot command. Methods: '__init__' -- start up the program. '__call__' -- pass an arbitrary string to the gnuplot program, followed by a newline. 'write' -- pass an arbitrary string to the gnuplot program. 'flush' -- cause pending output to be written immediately. """ def __init__(self, persist=None): """Start a gnuplot process. Create a 'GnuplotProcess' object. This starts a gnuplot program and prepares to write commands to it. Keyword arguments: 'persist=1' -- start gnuplot with the '-persist' option, (which leaves the plot window on the screen even after the gnuplot program ends, and creates a new plot window each time the terminal type is set to 'x11'). This option is not available on older versions of gnuplot. """ if persist is None: persist = GnuplotOpts.prefer_persist if persist: if not test_persist(): raise ('-persist does not seem to be supported ' 'by your version of gnuplot!') self.gnuplot = popen('%s -persist' % GnuplotOpts.gnuplot_command, 'w') else: self.gnuplot = popen(GnuplotOpts.gnuplot_command, 'w') # forward write and flush methods: self.write = self.gnuplot.write self.flush = self.gnuplot.flush def __call__(self, s): """Send a command string to gnuplot, followed by newline.""" self.write(s + '\n') self.flush()