The Group(f, L) function groups list L into sublists where procedure f returns either true or false. The value of procedure f is determined by the expression $f\left(x\right)$ evaluated for each element x of list L.

The Group(f, L, opts) function performs in a similar manner, except that the value of procedure f is determined by the expression $f\left(x\,\mathrm{opts}\right)$.

If Group is indexed by a positive integer N, the expression $f\left({\mathrm{opt}}_1,...,{\mathrm{opt}}_{N-1},x,\mathrm{opts}\right)$ is evaluated for each list element x.

$\mathrm{with}\left(\mathrm{ListTools}\right)\:$

$L≔\left[\mathrm{`\$`}\left(1..10\right)\right]$

$L≔\left[1\,2\,3\,4\,5\,6\,7\,8\,9\,10\right]$

$\mathrm{Group}\left(\mathrm{isprime}\,L\right)$

$\left[1\right],\left[2\,3\right],\left[4\right],\left[5\right],\left[6\right],\left[7\right],\left[8\,9\,10\right]$

$\mathrm{Group}\left(\mathrm{type}\,L\,'\mathrm{even}'\right)$

$\left[1\right],\left[2\right],\left[3\right],\left[4\right],\left[5\right],\left[6\right],\left[7\right],\left[8\right],\left[9\right],\left[10\right]$

$\mathrm{Digits}≔5$

$\mathrm{Digits}≔5$

$\mathrm{Group}\left(\mathrm{`>`}\,\left[\mathrm{seq}\left(\sin \left(2.0x\right)\,x=1..12\right)\right]\,-\frac{1}{2}\right)$

$\left[0.90930\right],\left[\mathrm{-0.75680}\right],\left[\mathrm{-0.27942}\,0.98936\right],\left[\mathrm{-0.54402}\,\mathrm{-0.53657}\right],\left[0.99061\,\mathrm{-0.28790}\right],\left[\mathrm{-0.75099}\right],\left[0.91295\,\mathrm{-0.0088513}\right],\left[\mathrm{-0.90558}\right]$

$\mathrm{Group}\left(\mathrm{evalb}\circ \mathrm{`>`}\,\left[\mathrm{seq}\left(\sin \left(2.0x\right)\,x=1..12\right)\right]\,-\frac{1}{2}\right)$

$\left[0.90930\right],\left[\mathrm{-0.75680}\right],\left[\mathrm{-0.27942}\,0.98936\right],\left[\mathrm{-0.54402}\,\mathrm{-0.53657}\right],\left[0.99061\,\mathrm{-0.28790}\right],\left[\mathrm{-0.75099}\right],\left[0.91295\,\mathrm{-0.0088513}\right],\left[\mathrm{-0.90558}\right]$

$\mathrm{Group}\left[2\right]\left(\mathrm{verify}\,-\frac{1}{2}\,\left[\mathrm{seq}\left(\sin \left(2x\right)\,x=1..12\right)\right]\,\mathrm{less\_than}\right)$

$\left[\sin \left(2\right)\right],\left[\sin \left(4\right)\right],\left[\sin \left(6\right)\,\sin \left(8\right)\right],\left[\sin \left(10\right)\,\sin \left(12\right)\right],\left[\sin \left(14\right)\,\sin \left(16\right)\right],\left[\sin \left(18\right)\right],\left[\sin \left(20\right)\,\sin \left(22\right)\right],\left[\sin \left(24\right)\right]$