number of kernels cannot exceed 6

[benweishi]

When I try to do 7 kernels together.

import numpy
import perfplot

perfplot.show(
    setup=numpy.random.rand,
    kernels=[
        lambda a: numpy.c_[a, a],
        lambda a: numpy.stack([a, a]).T,
        lambda a: numpy.vstack([a, a]).T,
        lambda a: numpy.column_stack([a, a]),
        lambda a: numpy.concatenate([a[:, None], a[:, None]], axis=1),
        lambda a: numpy.c_[a, a],
        lambda a: numpy.stack([a, a]).T
        ],
    labels=['c_', 'stack', 'vstack', 'column_stack', 'concat', 'c_1', 'stack1'],
    n_range=[2**k for k in range(5)],
    xlabel='len(a)'
    )

I get this error:

IndexError                                Traceback (most recent call last)
<ipython-input-26-2c6678d2791b> in <module>()
     15     labels=['c_', 'stack', 'vstack', 'column_stack', 'concat', 'c_1', 'stack1'],
     16     n_range=[2**k for k in range(5)],
---> 17     xlabel='len(a)'
     18     )

/usr/local/lib/python3.6/dist-packages/perfplot/main.py in show(*args, **kwargs)
    208 
    209 def show(*args, **kwargs):
--> 210     out = bench(*args, **kwargs)
    211     out.show()
    212     return

/usr/local/lib/python3.6/dist-packages/perfplot/main.py in bench(setup, kernels, n_range, labels, colors, xlabel, title, target_time_per_measurement, logx, logy, automatic_order, equality_check)
    152 
    153     data = PerfplotData(
--> 154         n_range, timings, labels, colors, xlabel, title, logx, logy, automatic_order
    155     )
    156     return data

/usr/local/lib/python3.6/dist-packages/perfplot/main.py in __init__(self, n_range, timings, labels, colors, xlabel, title, logx, logy, automatic_order)
     50             self.timings = self.timings[order]
     51             self.labels = [self.labels[i] for i in order]
---> 52             self.colors = [self.colors[i] for i in order]
     53         return
     54 

/usr/local/lib/python3.6/dist-packages/perfplot/main.py in <listcomp>(.0)
     50             self.timings = self.timings[order]
     51             self.labels = [self.labels[i] for i in order]
---> 52             self.colors = [self.colors[i] for i in order]
     53         return
     54 

IndexError: list index out of range

If I use automatic_order = False, the error would not happen, but the result plot only show 6 of them.

[nschloe]

I cannot reproduce the problem, and looking at the code I cannot see what this should occur. Are you running an old version of perfplot?

[nschloe]

Closing for lack of feedback. Feel free to reopen at any time.

[benweishi]

Sorry for the late feedback. You are right, I can't reproduce this error locally, including local Jubyter notebook. The error only happens on the colab.research.google.com platform. I install the perfplot using !pip install -U perfplot. I'm sharing this notebook:
https://colab.research.google.com/drive/1P_c8gI3sVjP30-bH0ezcs87USAOvb39I