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#!/usr/bin/env python3
#
# tutor.c
# Tony Richardson
#
# This program is intended to be used as a template for creating simple
# two-dimensional plotting programs which use the PLplot plotting
# library. The program was written with an emphasis on trying to clearly
# illustrate how to use the PLplot library functions.
#
# This program reads data for M lines with N points each from an input
# data file and plots them on the same graph using different symbols. It
# draws axes with labels and places a title at the top of the figure. A
# legend is drawn to the right of the figure. The input data file must
# have the following format:
#
# x[1] x[2] x[3] . . . x[N]
# y1[1] y1[2] y1[3] . . . y1[N]
# y2[1] y2[2] y2[3] . . . y2[N]
# . . . . . . .
# . . . . . . .
# . . . . . . .
# yM[1] yM[2] yM[3] . . . yM[N]
#
# For example:
#
# 0 1 2 3 4
# 1.2 1.5 1.6 1.9 2.0
# 1.1 1.3 1.8 2.1 2.3
# 1.3 1.6 1.8 2.0 2.2
#
# (The first line contains the x-coordinates. The succeeding M lines
# contain the y-coordinates of each of the M lines.)
import pl
import string
import sys
# You can select a different set of symbols to use when plotting the
# lines by changing the value of OFFSET.
OFFSET = 2
def main():
# Here are the character strings that appear in the plot legend.
legend = ["Aardvarks", "Gnus", "Llamas"]
# ============== Read in data from input file. =============
# Parse and process command line arguments
pl.ParseOpts(sys.argv, pl.PARSE_FULL)
# First prompt the user for the input data file name
filename = raw_input("Enter input data file name.\n")
# and open the file.
try:
datafile = open(filename, "r")
except:
error("Error opening input file.")
# Read in all the data.
try:
lines = datafile.readlines()
datafile.close()
x = []
data = string.split(lines[0])
for num in data:
x.append(string.atof(num))
y = []
del lines[0]
for line in lines:
yy = []
data = string.split(line)
for num in data:
yy.append(string.atof(num))
y.append(yy)
except:
error("Error while reading data file.")
# ============== Graph the data. =============
# Set graph to portrait orientation. (Default is landscape.)
# (Portrait is usually desired for inclusion in TeX documents.)
pl.sori(-1)
# Initialize plplot
pl.init()
# We must call pladv() to advance to the first (and only) subpage.
# You might want to use plenv() instead of the pladv(), plvpor(),
# plwind() sequence.
pl.adv(0)
# Set up the viewport. This is the window into which the data is
# plotted. The size of the window can be set with a call to
# plvpor(), which sets the size in terms of normalized subpage
# coordinates. I want to plot the lines on the upper half of the
# page and I want to leave room to the right of the figure for
# labelling the lines. We must also leave room for the title and
# labels with plvpor(). Normally a call to plvsta() can be used
# instead.
pl.vpor(0.15, 0.70, 0.5, 0.9)
# We now need to define the size of the window in user coordinates.
# To do this, we first need to determine the range of the data
# values.
xmin, xmax = min(x), max(x)
ymin = ymax = y[0][0]
for yy in y:
yymin, yymax = min(yy), max(yy)
if yymin < ymin:
ymin = yymin
if yymax > ymax:
ymax = yymax
# Now set the size of the window. Leave a small border around the
# data.
xdiff = (xmax - xmin) / 20.
ydiff = (ymax - ymin) / 20.
pl.wind(xmin - xdiff, xmax + xdiff, ymin - ydiff, ymax + ydiff)
# Call plbox() to draw the axes (see the PLPLOT manual for
# information about the option strings.)
pl.box("bcnst", 0.0, 0, "bcnstv", 0.0, 0)
# Label the axes and title the graph. The string "#gm" plots the
# Greek letter mu, all the Greek letters are available, see the
# PLplot manual.
pl.lab("Time (weeks)", "Height (#gmparsecs)", "Specimen Growth Rate")
# Plot the data. plpoin() draws a symbol at each point. plline()
# connects all the points.
i = 0
for yy in y:
pl.poin(x, yy, i + OFFSET)
pl.line(x, yy)
i = i + 1
# Draw legend to the right of the chart. Things get a little messy
# here. You may want to remove this section if you don't want a
# legend drawn. First find length of longest string.
leglen = 0
for leg in legend:
j = len(leg)
if j > leglen:
leglen = j
# Now build the string. The string consists of an element from the
# legend string array, padded with spaces, followed by one of the
# symbols used in plpoin above.
M = len(y)
i = 0
for leg in legend:
if i >= M:
break
text = leg
j = len(text)
# pad string with spaces
if j < leglen:
k = leglen - j
text = text + ' ' * k
# pad an extra space
text = text + ' '
# insert the ASCII value of the symbol plotted with plpoin()
text = text + chr(i + OFFSET)
# plot the string
pl.mtex("rv", 1., 1. - float(i + 1) / (M + 1), 0., text)
i = i + 1
# Don't forget to call PLEND to finish off!
pl.end()
def error(str):
sys.stderr.write(str)
sys.stderr.write('\n')
sys.exit(1)
main()
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