A suggestion on the mandelbrot one-liner in the docs FAQ

[matheusja]

Documentation

On the docs FAQ there's a about obfuscated one-liners. The third one is a about the mandelbrot fractal, using the code:

print((lambda Ru,Ro,Iu,Io,IM,Sx,Sy:reduce(lambda x,y:x+y,map(lambda y,
Iu=Iu,Io=Io,Ru=Ru,Ro=Ro,Sy=Sy,L=lambda yc,Iu=Iu,Io=Io,Ru=Ru,Ro=Ro,i=IM,
Sx=Sx,Sy=Sy:reduce(lambda x,y:x+y,map(lambda x,xc=Ru,yc=yc,Ru=Ru,Ro=Ro,
i=i,Sx=Sx,F=lambda xc,yc,x,y,k,f=lambda xc,yc,x,y,k,f:(k<=0)or (x*x+y*y
>=4.0) or 1+f(xc,yc,x*x-y*y+xc,2.0*x*y+yc,k-1,f):f(xc,yc,x,y,k,f):chr(
64+F(Ru+x*(Ro-Ru)/Sx,yc,0,0,i)),range(Sx))):L(Iu+y*(Io-Iu)/Sy),range(Sy
))))(-2.1, 0.7, -1.2, 1.2, 30, 80, 24))

I suggest 2 changes:

1. Replace reduce(lambda x, y: x+y, <...>) with ''.join(<...>)

2. Make the outer join intersperse the lines with a newline character instead of relying on line wrapping. This will turn the outer ''.join(<...>) into '\n'.join(<...>)

This results on the following code:

print((lambda Ru,Ro,Iu,Io,IM,Sx,Sy:'\n'.join(map(lambda y,
Iu=Iu,Io=Io,Ru=Ru,Ro=Ro,Sy=Sy,L=lambda yc,Iu=Iu,Io=Io,Ru=Ru,Ro=Ro,i=IM,
Sx=Sx,Sy=Sy:''.join(map(lambda x,xc=Ru,yc=yc,Ru=Ru,Ro=Ro,
i=i,Sx=Sx,F=lambda xc,yc,x,y,k,f=lambda xc,yc,x,y,k,f:(k<=0)or (x*x+y*y
>=4.0) or 1+f(xc,yc,x*x-y*y+xc,2.0*x*y+yc,k-1,f):f(xc,yc,x,y,k,f):chr(
64+F(Ru+x*(Ro-Ru)/Sx,yc,0,0,i)),range(Sx))):L(Iu+y*(Io-Iu)/Sy),range(Sy
))))(-2.1, 0.7, -1.2, 1.2, 30, 80, 24))

You can see the result and compare both on the following colab link: https://colab.research.google.com/drive/1NWfwNH_o5GPRTWwCdS-pVQLwEOSgstnz?usp=sharing

[serhiy-storchaka]

I think that it goes against the initial purpose of these examples: showing an obfuscated code with lambdas.

The first example

print(list(filter(None,map(lambda y:y*reduce(lambda x,y:x*y!=0,
map(lambda x,y=y:y%x,range(2,int(pow(y,0.5)+1))),1),range(2,1000)))))

could be rewritten in shorter and clearer form which does not use explicit lambdas at all:

print([y for y in range(2,1000) if all(y%x for x in range(2,int(y**0.5+1)))])

But then it would not be a good example for this question.

[matheusja]

Fair enough. Even then, I'm annoyed at the fact that the code doesn't explicitly insert newlines, is it possible to send another pull request, except changing only the part which concatenates lines?

The code would be:

print((lambda Ru,Ro,Iu,Io,IM,Sx,Sy:reduce(lambda x,y:x+'\n'+y,map(lambda y,
Iu=Iu,Io=Io,Ru=Ru,Ro=Ro,Sy=Sy,L=lambda yc,Iu=Iu,Io=Io,Ru=Ru,Ro=Ro,i=IM,
Sx=Sx,Sy=Sy:reduce(lambda x,y:x+y,map(lambda x,xc=Ru,yc=yc,Ru=Ru,Ro=Ro,
i=i,Sx=Sx,F=lambda xc,yc,x,y,k,f=lambda xc,yc,x,y,k,f:(k<=0)or (x*x+y*y
>=4.0) or 1+f(xc,yc,x*x-y*y+xc,2.0*x*y+yc,k-1,f):f(xc,yc,x,y,k,f):chr(
64+F(Ru+x*(Ro-Ru)/Sx,yc,0,0,i)),range(Sx))):L(Iu+y*(Io-Iu)/Sy),range(Sy
))))(-2.1, 0.7, -1.2, 1.2, 30, 80, 24))

The results may be seen on the collab link:

https://colab.research.google.com/drive/1RHtPuTYqwLiRh7S8SckI-cZj50fgvzGt#scrollTo=VJaN5YFEedqe

[gpshead]

thanks!

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