[CentOS] Conversion of text in shell

[Ross S. W. Walker]

Ross S. W. Walker
> 
> Ross S. W. Walker wrote:
> > 
> > roland hellström wrote:
> > > 
> > > OK! I finally figured out the solution for all you people out 
> > > the eager to hear it!!!
> > > it was infact very very similar to the last line I sent... 
> > this is it
> > > sed 's/\([^\.]*\).\([^,]*\),\([^\.]*\).\([^e]*\)e\(.*\)/\1,\2 
> > > \& $\3,\4 \\cdot 10^{\5}$\\\\/'
> > > 
> > > omg I feel so h4xx0r figuring that out myself lol
> > > Thx for the help all :)
> > 
> > I am surprised you got it all in 1 regex, I was aiming more for:
> > 
> > sed 's/,/ & /;s/\./,/;s/\(.*\)e\(.*\)/\1 \\cdot 10^{\2}/'
> 
> whoops, I made a mistake:
> 
> sed 's/,/ \& /;s/\./,/g;s/\(.*\)e\(.*\)/\1 \\cdot 10^{\2}\$\\\\/'
> 
> You need the 'g' option in the second substitute to perform a
> global, and of course the proper cdot expression.

Ok, not to toot my own horn, but it turns out that doing 3 simple
regexs is actually quicker then 1 complex regex, though with today's
processors you need to run it over a large set to see:

# wc -l test
20691 test

# time sed 's/\([^\.]*\).\([^,]*\),\([^\.]*\).\([^e]*\)e\(.*\)/\1,\2 \& $\3,\4 \\cdot 10^{\5}$\\\\/' test >/dev/null

real    0m0.175s
user    0m0.174s
sys     0m0.000s

# time sed 's/,/ \& \$/;s/\./,/g;s/\(.*\)e\(.*\)/\1 \\cdot 10^{\2}\$\\\\/' test >/dev/null

real    0m0.141s
user    0m0.139s
sys     0m0.001s

So not only is it simpler to divide and conqueror a problem, but
often it produces the best results...

-Ross

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