Line duplicate points fix

[chaosphere2112]

When using lines in vcs, a bug would add many duplicate points to the line object. Here's a sample:

import vcs

x = vcs.init()

l = x.createline()

l.x = [[0, .5], [0, .75], [0, 1]]
l.y = [[0, .5], [0, .75], [0, 1]]

print l.x
print l.y

x.plot(l, bg=1)

print l.x
print l.y

which outputs

[[0, 0.5], [0, 0.75], [0, 1]]
[[0, 0.5], [0, 0.75], [0, 1]]
[[0, 0.5, 0.5], [0, 0.75, 0.75], [0, 1, 1]]
[[0, 0.5, 0.5], [0, 0.75, 0.75], [0, 1, 1]]

I spruced up the prepLine function in vcs2vtk.py, and renamed the ambiguous variables that led to the bug. I also added a test that makes sure that the X and Y points are being extended correctly.

[alliepiper]

@doutriaux1 This looks like the same issue we had in 46105aa. Can you check the similar functions in this file and make sure they're treating both n and N correctly?

I think this while len(a) < number_points: a.append(a[-1]) bit should just be assert(len(a) == number_points)(or similar failure) here, too, unless this is an expected feature. Otherwise it would likely just mask user mistakes and give unexpected incorrect results.

[doutriaux1]

Well I'm open to this, but historically it would pad it for the user with the last value.

[alliepiper]

Gotcha. As long as it's doing what they'd expect it to!

[alliepiper]

Oops, and I'd linked the wrong commit earlier -- I meant to point at this one: d8f725a

[aashish24]

is this still valid?

[chaosphere2112]

Yup. Looks like it's still doing it.

In [1]: l = vcs.createline()

In [2]: l.x = [[0, .5], [0]]

In [3]: l.y = [[0, .5], [0]]

In [4]: x.line(l)
Out[4]: <vcs.displayplot.Dp at 0x111a548c0>

In [5]: l.x
Out[5]: [[0, 0.5], [0, 0]]

In [6]: l.y
Out[6]: [[0, 0.5], [0, 0]]

[doutriaux1]

@chaosphere2112 can you also please add the test to CMakeList.txt in testing/vcs ?

Thanks,

C.

[chaosphere2112]

Oh, yeah, that would probably be helpful 😅

[doutriaux1]

dont' worry I did it

[chaosphere2112]

Ah, thanks!