Plotting maps Science

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Plotting mapsScience ComputersPHY307/PHY607S
ept. 17, 2002

• Homework
• Lists cute object tricks
• Graphing functions and lists
• In search of patterns graphing map histories.

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Homework

• See notes online about logistic map and color.
  Sample program will also posted.
• Quartic map should be similar to the logistic map
  qualitatively, but differs in quantitative detail.

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Lists

• Lists can be of numbers, boxs, other lists
• 1,2,3,4
• boxa, boxb
• 1,2,3,4,5,2
• Lists can be made using, for example, range()
• listA range(0,100,5)

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Lists

• Lists can be appended to
• listA 1,2,5
• listA.append(6)
• print listA

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Lists

• Another example
• listA empty list
• listA.append(box(x0))
• listA.append(box(x2))
• while 1 loop forever
• rate(20)
• for abox in listA for each box
• abox.y abox.y 0.01 move up

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What does this do?

• from visual import
• scene.autoscale 0
• objlist
• for j in range(30)
• objlist.append(ring(xj-15))
• while 1
• rate(20)
• for r in objlist
• r.rotate(angle0.01,axis(0,1,0))

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Graphing

• Lists of data can be plotted in VPython
• Need extra statement
• from visual.graph import
• This gives ability to do 2D plots.

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integers are not real

• Try out
• print 2/3
• print 2./3.
• If not careful, and divide an integer by an
  integer, can run into trouble. So
• Use . with abandon, e.g., a a 2.0
• Use arange instead of range

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For example

• from visual.graph import
• data
• for x in arange(0, 2, 0.01)
• data.append((x, xx))
• curveA gcurve(posdata, colorcolor.red)

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Plotting one point at a time

• from visual.graph import
• curveA gdots()
• for x in range(0, 200)
• rate(6)
• curveA.plot(pos(x,sin(x/10.)))

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Plotting map histories

• from visual.graph import
• curveA gdots()
• y 0.5
• for t in range(0, 40)
• rate(3)
• y y 0.95
• curveA.plot(pos(t,y))