Objective:  We are going to create a portrait page with 2 plots, first plot on top will be composed of two curves.

You can download  the full source code. To run the source code at the command line, type: "python xmgrace_tutorial_Numeric.py".


First lets create some data to plot

#import module MA
import MA

# First let's create some data
npoints=50
X=MA.arrayrange(npoints,typecode=MA.Float)
X=X/float(npoints)*2.*MA.pi

Y1=MA.sin(X)
Y2=MA.cos(X)
Y3=MA.tan(X

and set a current directory (it will be needed when we save the plots to the output files).

TEMPDIR = './'

Now let's import xmgrace module

# xmgrace module is inside the genutil package
from genutil import xmgrace

and initialize xmgrace

# create our xmgrace object
x=xmgrace.init() 

The picture below shows the effect of this command - the initialization of the xmgrace window

First let's set our graphs area, for the two plots we need two graphs initialized. Also we'll make the page a portrait page.

# First let's set our graphs area
# graph 0, exist by default, but we need to add 1 graph, therefore:
x.add_graph() # adds one graph to our graph list (x.Graph) 
# Let's change the orientation of the page to portrait
x.portrait()

Set the area for the graph 0 and the graph 1

# Now let's set the area of graph 0
x.Graph[0].vymin=.55  # starts at 55% of the page
x.Graph[0].vymax=.9   # stops at 90% of the page
x.Graph[0].vxmin=.1  # starts at 10% of the page
x.Graph[0].vxmax=.75   # stops at 75% of the page
# and the area of graph 1
x.Graph[1].vymin=.1 # starts at 10% of the page
x.Graph[1].vymax=.45 # 45 % of page
# Let's offset the 2 graphs just for fun
x.Graph[1].vxmin=.25  # starts at 55% of the page
x.Graph[1].vxmax=.9   # stops at 90% of the page

Set some titiles and subtitles for the graphs

# let's set the titles and subtitles
x.Graph[0].title='TRIGO'
x.Graph[0].stitle='SIN and COS'
x.Graph[1].stitle='TAN'

And the Y axis ranges for both graphs together with the tick marks

# ok now let's set the min ans max for the Y axis
x.Graph[0].yaxis.min=-1. # ymin for graph 0
x.Graph[0].yaxis.max=1. # ymax for graph 0
x.Graph[1].yaxis.min=-1.5 # ymin for graph 1
x.Graph[1].yaxis.max=1.5  # ymax for graph 1

# Now let's set the tick marks for Graph 0
x.Graph[0].yaxis.tick.inc=1 # Main tick every unit
x.Graph[0].yaxis.tick.minor_ticks=4 # 4 sub in between , 1 every .25 units
# Now let's set the tick marks for Graph 1
x.Graph[1].yaxis.tick.inc=10 # Main tick every 10
x.Graph[1].yaxis.tick.minor_ticks=4 # 4 sub in between , 1 every 2.5 units

Set X axis and it's tick marks

# X values are between 0 and 2pi
# therefore let's set the axis  from -1,1
x.Graph[0].xaxis.min=0.
x.Graph[0].xaxis.max=2.*MA.pi
x.Graph[1].xaxis.min=0.
x.Graph[1].xaxis.max=2.*MA.pi

# Set the xaxis ticks
dic={0.:'0',MA.pi/2:'PI/2',MA.pi:'PI',3*MA.pi/2:'3PI/2',2*MA.pi:'2PI'}
x.Graph[0].xaxis.tick.spec.loc=dic
# way 2 the "less convential" way
x.Graph[1].xaxis.tick.spec.loc=dic
# Finally let's reduce the size a bit
x.Graph[0].xaxis.tick.label.char_size=.8
x.Graph[1].xaxis.tick.label.char_size=.8

Set the legends for both graphs

# now the legend
x.Graph[0].legend.char_size=.8
x.Graph[0].legend.x=.8  # Legend at 80% in x
x.Graph[0].legend.x=.8  # Legend at 80% in y
#or
x.Graph[1].legend.char_size=.8
x.Graph[1].legend.x=.05
x.Graph[1].legend.y=.35

We want to have two curves (sets) on one graph, by default we have 1 set  per graph, so we need to add another one to  the  graph 0

# Ok now let's play with the appearence of the sets themself
# Ok by default we only have 2 sets (1 per graph)
# So we need to add 2 sets
x.add_set(0) # adding to graph 0 (since it's graph 0, the 0 is optional)

Now lets set the line widths, colors and linestyles

# First let's change the line width
x.Graph[0].Set[0].line.linewidth=2
x.Graph[0].Set[1].line.linewidth=2
x.Graph[1].Set[0].line.linewidth=2
# Let's set the colors
x.Graph[0].Set[0].line.color='red' # xmgrace default colors are coded
x.Graph[0].Set[1].line.color=4 # color 4 is blue
# Let's define a new color for the tangeante
x.add_color('purple')
x.Graph[1].Set[0].line.color='purple' # use the color we just defined
# Let's set the second's set style to dash
x.Graph[1].Set[0].line.linestyle='solid'
x.Graph[0].Set[1].line.linestyle='dash'
x.Graph[0].Set[0].line.linestyle=2 # 2 is dot

and define the legends for each set

# Now let's set the name for each set, to be used in the legend
x.Graph[0].Set[0].legend='SIN'
x.Graph[0].Set[1].legend='COS'
x.Graph[1].Set[0].legend='TAN'

We would like to have a zero line plotted, so let's add that

# ok one last trick, in order to have the 0 line plotted
# let's create a dummy array with zeros in it:
zero=[0,0]
# add a dataset and assign it graph 1 black color
x.add_set(1,'black')

Also let's play with adding some text to the page

# Finally just for fun let's place a big red "Sample" accross it
x.add_string(0.5,0.5,'Sample',color='red',char_size=9,rot=55,just=14)

Now we can plot all the graphs

# And plot these babies:
x.plot([Y1,Y2,Y3,zero],xs=[X,X,X,[0.,2.*MA.pi] ]) 
# You MUST pass a list of slab, even if only one slab
# or you can plot then 1 by 1

We will improve on the plots by adding an error bars.
First we need to clean up the plots

# first let's clear
x('kill G0.S0')
x('kill G0.S1')
x('kill G1.S0')
x('kill G1.S1')

Let' s add the mask to the tanget

# Now the tan is pretty ugly because of extreme let's mask everything
# that is greater than 1.5 and redraw that
Y3=MA.masked_greater(Y3,1.5)

and error bars for all the plots

# Also we're going to add error bars 10% of the value
# dx for the sin
YY1=MA.zeros((2,npoints),typecode=MA.Float)
YY1[0]=Y1
YY1[1]=Y1*.1
x.Graph[0].Set[0].type='xydx'
x.Graph[0].Set[0].errorbar.status='on'
x.Graph[0].Set[0].errorbar.color='red'
# dy for the cos
YY2=MA.zeros((2,npoints),typecode=MA.Float)
YY2[0]=Y2
YY2[1]=Y2*.1
x.Graph[0].Set[1].type='xydy'
x.Graph[0].Set[1].errorbar.status='on'
x.Graph[0].Set[1].errorbar.color=x.Graph[0].Set[1].line.color
# dy and dx for the tan
YY3=MA.zeros((3,npoints),typecode=MA.Float)
YY3[0]=Y3
YY3[1]=Y3*.1
YY3[2]=Y3*.1
x.Graph[1].Set[0].type='xydxdy'
x.Graph[1].Set[0].errorbar.status='on'
x.Graph[1].Set[0].errorbar.color='purple'

Now we can plot it again. We will plot each set separately, first we will plot first set (set 0) on graph 0

#plot first set from first graph
x.plot(YY1,xs=X,G=0,S=0)

and add the second set (set 1) to graph 0

#plot second set from first graph
x.plot(YY2,xs=X,G=0,S=1)

Finally let's put the second graph and the first set (tangent line)

#plot first set from second graph
x.plot(YY3,xs=X,G=1,S=0)

and add the zero line as a second set to the second graph

# Now since we are passing lists and not MAs we need to wrap them into a list
x.plot([zero],xs=[[0.,2.*MA.pi] ],G=1,S=1)

Here is our final page

Now we can save it to the different output file formats as follows:

# Finally let's save the result
x.ps(TEMPDIR+'xmgrace_demo_Numeric') # postscript
x.ps(TEMPDIR+'xmgrace_demo_Numeric_gray',color='grayscale') # grayscale postscript
x.jpeg(TEMPDIR+'xmgrace_demo_Numeric',dpi=300,quality=80) # jpeg 300dpi, 80% quality compression
x.pdf(TEMPDIR+'xmgrace_demo_Numeric')
x.eps(TEMPDIR+'xmgrace_demo_Numeric')
x.svg(TEMPDIR+'xmgrace_demo_Numeric')
x.mif(TEMPDIR+'xmgrace_demo_Numeric')
x.pnm(TEMPDIR+'xmgrace_demo_Numeric')
x.png(TEMPDIR+'xmgrace_demo_Numeric')
x.metafile(TEMPDIR+'xmgrace_demo_Numeric')

 Lastly we will clean up by closing the xmgrace window.

# Finish
x.close()