If your collection of points is a numpy array, you can use the column of y-coordinates as the first argument to the plotting function hlines. E.g, inside ipython --pylab:

ptn = array(([1,1],[3,1],[2,4],[4,4]))  
hlines(ptn[:,1], -1, 1)

But at that point the horizontal lines are on the edges of the axis, not visible. This forces them to show:

plot([-1, 0, 1],[0.5, 2.5, 4.5])

but perhaps you only want the hlines. What I usually do in a script or function is name all my axes and twiddle their limits in an aesthetic way, but in ipython the following isn't redrawing the plot, for me:

a = gca()
curlims = a.get_ylim()
a.set_ylim([curlims[0] - 0.1, curlims[1] + 0.1]) 

half-finished, but I hope it helps,


On Jul 13, 2009, at 13 Jul, 11:56 AM, Afi Welbeck wrote:


I'm a newbie, and I'm trying to plot horizontal
 with the following  points: 
[1,1], [3,1], [2,4] and [4,4]. 

Also, is there a way of putting them together in
lists, (say the pair of points that plot one horizontal line )
for easy plotting? Could anyone please help me with the
code? Thanks.

Harriet A. Welbeck

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