Dictionary u将选择[list，UnitStep[list[[All，2]]]-3]，1]添加到测试列表中。它不像其他的那么清晰，但是速度很快。 list = {{a, b, c, d}, {1, 2, 3, 4}, {5, 6, 7, 8}}; {5, 6, 7,

u将

选择[list，UnitStep[list[[All，2]]]-3]，1]

添加到测试列表中。它不像其他的那么清晰，但是速度很快。

list = {{a, b, c, d}, {1, 2, 3, 4}, {5, 6, 7, 8}};

{5, 6, 7, 8}

Select[#, # > 2 &] & /@ list[[2 ;;]

Cases[list, x_List /; x[[2]] > 2]

Cases[list, _List?(#[[2]] > 2 &)]

Cases[list, {_, x_, ___} /; x > 2]
Out[1] = {{5, 6, 7, 8}}

Cases[list, {x___} /; List[x][[2]] > 2]
Out[2] = {{5, 6, 7, 8}}

Select[list, #[[2]] > 3 &]

{{5, 6, 7, 8}}

In[45]:= Cases[list, {_, _?(# > 3 &), ___}]
Out[45]= {{5, 6, 7, 8}}

list = {{a, b, c, d}, {1, 2, 3, 4}, {5, 6, 7, 8}};

Pick[list, #>3& /@ list[[All, 2]] ]

selectByColumn[array_, index_, value_, range_] :=
  Select[array, #[[index]] > value &][[All, range]]

solutions = Hold[
   Select[list, #[[2]] > 3 &],
   Cases[list, _List?(#[[2]] > 3 &)],
   Cases[list, x_List /; x[[2]] > 3],
   Cases[list, {_, x_, ___} /; x > 3],
   Cases[list, {_, _?(# > 3 &), ___}],
   Cases[list, {x___} /; List[x][[2]] > 3],
   Pick[list, UnitStep[list[[All, 2]] - 3], 1],
   Pick[list, # > 3 & /@ list[[All, 2]]]
   ];
testCases = Hold[
   {"Packed Reals", RandomReal[{0, 5}, {dim, dim}]},
   {"Unpacked Reals", 
    Developer`FromPackedArray@RandomReal[{0, 5}, {dim, dim}]},
   {"Packed Integers", RandomInteger[{0, 5}, {dim, dim}]},
   {"Unpacked Integers", 
    Developer`FromPackedArray@RandomInteger[{0, 5}, {dim, dim}]},
   {"Rationals", 
    Rationalize[#, .001] & /@ RandomReal[{0, 5}, {dim, dim}]}
   ];
timing := 
  Function[Null, 
   If[(time = First[Timing[Do[#;, {n}]]]) < .3, 
     Print["Too small timing for ", n, " iterations (dim=", dim, 
      ") of ", HoldForm[#], ": ", time, " seconds!"]; time, time]/n, 
   HoldFirst];
generateTable := 
 Labeled[TableForm[
   Transpose@
    Table[list = testCases[[i, 2]]; 
     tmgs = List @@ (timing /@ solutions); 
     d = Last@MantissaExponent[Min[tmgs]] - 3; 
     Row[{Round[10^-d*#], ".\[Times]", Superscript[10, d]}] & /@ 
      tmgs, {i, 1, Length[testCases]}], 
   TableHeadings -> {List @@ (HoldForm /@ solutions), 
     List @@ testCases[[All, 1]]}, TableAlignments -> Right], 
  Row[{"Average timings for ", dim, "\[Times]", dim, " list"}], Top]

Column[{dim = 5; n = 30000; generateTable, dim = 100; n = 3000; 
  generateTable, dim = 1000; n = 150; generateTable}, Left, 1, 
 Frame -> All, FrameStyle -> Gray]