Mathematica Programming » Functional Programming
Map / Scan
Note that often we can even one-up Table
and Do
in terms of simplicity, while losing no performance. Map
and Scan
pass an argument from a list to a function, much as Table
and Do
iterate over a range or list:
Table[PrimeQ@i,{i,10^6}]//
AbsoluteTiming//First
0.369371`
compared to
Map[PrimeQ,Range[10^6]]//
AbsoluteTiming//First
0.3625`
Even better, though, Map
has a more compact in-line syntax:
PrimeQ/@Range[10^6]//
AbsoluteTiming//First
0.374421`
Over time you will start thinking in this new syntax. Rather than “map prime-q over range of 10^6” you will start to think “prime-q slash at range of 10^6”.
Note that both Map
and Table
generate output, while their equivalents Scan
and Do
don’t. Even though Scan
does not have in-line syntax it is worth getting to know, as it can sometimes be more efficient than Do
and is, of course, vastly more efficient than For