## [PyX-user] Draw a line between some data points

 [PyX-user] Draw a line between some data points From: Riccardo Campana - 2006-12-04 16:56:27 ```Hello, I plotted the points from a data file, e.g.: 0.194 0.854 0.451 0.907 0.660 0.124 0.834 0.195 0.022 0.911 0.055 0.216 0.275 0.704 0.311 0.554 0.641 0.687 0.386 0.543 with the standard command g = graph.graphxy(width=8,height=8) g.plot(graph.data.file("datafile.dat", x=1, y=2), [graph.style.symbol (graph.style.symbol.circle, size=0.1, symbolattrs=[deco.filled])]) Now, I want to draw a straight line between some of these points, for example from the point (0.194, 0.854) to the point (0.311, 0.554). How can I do this? With path.line() and stroke() the points are not in graph (axis) coordinates... Thank you in advance, Riccardo Campana ```

 [PyX-user] Draw a line between some data points From: Riccardo Campana - 2006-12-04 16:56:27 ```Hello, I plotted the points from a data file, e.g.: 0.194 0.854 0.451 0.907 0.660 0.124 0.834 0.195 0.022 0.911 0.055 0.216 0.275 0.704 0.311 0.554 0.641 0.687 0.386 0.543 with the standard command g = graph.graphxy(width=8,height=8) g.plot(graph.data.file("datafile.dat", x=1, y=2), [graph.style.symbol (graph.style.symbol.circle, size=0.1, symbolattrs=[deco.filled])]) Now, I want to draw a straight line between some of these points, for example from the point (0.194, 0.854) to the point (0.311, 0.554). How can I do this? With path.line() and stroke() the points are not in graph (axis) coordinates... Thank you in advance, Riccardo Campana ```
 Re: [PyX-user] Draw a line between some data points From: Andre Wobst - 2006-12-04 17:35:30 ```Hi, On 04.12.06, Riccardo Campana wrote: > Hello, > I plotted the points from a data file, e.g.: > 0.194 0.854 > 0.451 0.907 > 0.660 0.124 > 0.834 0.195 > 0.022 0.911 > 0.055 0.216 > 0.275 0.704 > 0.311 0.554 > 0.641 0.687 > 0.386 0.543 > > with the standard command > g = graph.graphxy(width=8,height=8) > g.plot(graph.data.file("datafile.dat", x=1, y=2), [graph.style.symbol > (graph.style.symbol.circle, size=0.1, symbolattrs=[deco.filled])]) > > Now, I want to draw a straight line between some of these points, for > example from the point (0.194, 0.854) to the point (0.311, 0.554). > > How can I do this? With path.line() and stroke() the points are not > in graph (axis) coordinates... You're absolutely right. Fortunately we already thought about this and created some handy conversion methods, which are part of the graph infrastructure. The only thing you need to understand is that you need to "finish" the graph (i.e. fix the layout) before you can start using those conversion methods. Before finishing the graph the axis ranges are not fixed ... So all you need to do is to call "g.finish()" after you plot commands. (Actually a g.dolayout() would already be enough.) Then you can convert points from axis coordinates to PyX lengths in the graph "canvas" by g.pos(): x1, y1 = g.pos(0.194, 0.854) x2, y2 = g.pos(0.311, 0.554) And than: g.stroke(path.line(x1, y1, x2, y2)) (I haven't checked the code but it should work along this line.) HTH, André -- by _ _ _ Dr. André Wobst / \ \ / ) wobsta@..., http://www.wobsta.de/ / _ \ \/\/ / PyX - High quality PostScript and PDF figures (_/ \_)_/\_/ with Python & TeX: visit http://pyx.sourceforge.net/ ```
 Re: [PyX-user] Draw a line between some data points From: - 2006-12-04 17:45:43 ```Hello, On 04.12.06, Riccardo Campana wrote: > Hello, >=20 > with the standard command > g =3D graph.graphxy(width=3D8,height=3D8) > g.plot(graph.data.file("datafile.dat", x=3D1, y=3D2), [graph.style.symb= ol=20 > (graph.style.symbol.circle, size=3D0.1, symbolattrs=3D[deco.filled])]) >=20 > Now, I want to draw a straight line between some of these points, for =20 > example from the point (0.194, 0.854) to the point (0.311, 0.554). >=20 > How can I do this? With path.line() and stroke() the points are not =20 > in graph (axis) coordinates... draw the lines directly on g which is a canvas. g.pos allows you to convert graph-coordinates into lengths g.finish() x1, y1 =3D g.pos(0.194, 0.854) x2, y2 =3D g.pos(0.311, 0.554) g.stroke(path.line(x1, y1, x2, y2)) If you want lines between all the points, just say instead in your plot command graph.style.line() in addition to graph.style.symbol(...) Michael. --=20 "A mathematician is a device for turning coffee into theorems" Paul Erd=F6s. ```