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[求助] 在看例子时有几个问题看不懂

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发表于 2012-6-20 08:59:43 | 显示全部楼层 |阅读模式
新手,在看netlogo自带的例子时,有几行程序看不懂,希望高手能够指点。2 K1 q2 I9 E! h3 Y# B( C0 r
netlogo自带的social science--traffic grid这一例子当中,
2 U8 `7 P9 I8 e6 b3 x3 P5 O! z1 ~+ Aglobals; t- w  H4 \1 T% _) Z2 ?8 ?
[0 h: R1 ?0 S, w8 ~& t) B; E+ O
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
5 ]* f, ^3 l" j- h3 L  grid-y-inc               ;; the amount of patches in between two roads in the y direction! P$ c0 N  g/ w4 b
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if# S% d2 p# \) g9 W( `  X& e  o
                           ;; it is to accelerate or decelerate9 B* k2 N. _! z3 t; ~0 l
  phase                    ;; keeps track of the phase
$ V/ K6 I: d' P# B  y  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure2 {  X2 i% E" L4 `9 c( R9 @
  current-light            ;; the currently selected light. S+ E0 l  p$ q+ m( a! W6 @6 |, o
7 f; {; R) g# Q5 T( n
  ;; patch agentsets
  v" i7 y+ c: i& S  g0 u  intersections ;; agentset containing the patches that are intersections, ]0 U5 j8 X& Y/ X% J
  roads         ;; agentset containing the patches that are roads& c0 S) o3 @* H& D. ?- f5 C7 t
]
; X2 T- Q/ X( y) Y! w: y6 d) D
3 {) W5 j+ S, K9 m. J% u" f. Vturtles-own
8 {, l2 L6 d3 G/ j[
- N0 R5 s1 N) ]  y) S. x, W. }  speed     ;; the speed of the turtle
: p( X# j0 i) [  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
% t: D) J+ a! U4 z4 u# N, ~6 N6 B  wait-time ;; the amount of time since the last time a turtle has moved$ M" T# o0 k3 n# M# Z/ X; `  x9 z
]" q8 _- `3 G4 v0 l. {
9 h) c$ [7 s. ~
patches-own- H* N$ ]! w; j8 `
[8 ]7 {1 d7 f9 t
  intersection?   ;; true if the patch is at the intersection of two roads4 E* j- w% l) f
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
/ A, `% L4 }; |/ G' \( @9 _                  ;; false for a non-intersection patches.
# s& U1 B' K/ H1 r# b6 O8 P  my-row          ;; the row of the intersection counting from the upper left corner of the
/ j0 b! B2 Y1 F& @                  ;; world.  -1 for non-intersection patches.
6 D. Y4 Y5 V; L, S  my-column       ;; the column of the intersection counting from the upper left corner of the9 D' F+ ]4 n9 n" [
                  ;; world.  -1 for non-intersection patches.! l9 @5 h3 p. o7 J6 q
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
% |( O6 s6 F* s+ s  auto?           ;; whether or not this intersection will switch automatically." g' [! f4 i/ y/ Q3 N4 i& {
                  ;; false for non-intersection patches.7 N, [8 J9 N( ^  t1 M
]4 S. M; N2 b8 Q' n) A" \9 }

8 P, c* V/ c; l5 }7 r. K8 ~
4 s' C  Z# _6 i& I# p;;;;;;;;;;;;;;;;;;;;;;* b0 |- a# u) ?) y4 }1 m
;; Setup Procedures ;;3 Y, G4 w: O' Y# c4 d$ w% }9 o
;;;;;;;;;;;;;;;;;;;;;;
( X4 L# t- n5 r* m
* _( j3 F# G( S5 t/ E$ m/ J: \;; Initialize the display by giving the global and patch variables initial values.+ J4 D5 Z) D; C$ N* I' z6 w" Y, E
;; Create num-cars of turtles if there are enough road patches for one turtle to: V/ k  r1 G0 m% ~' J
;; be created per road patch. Set up the plots.2 ?; j# s9 m2 E$ N; {* D
to setup
7 A; D0 z& I+ P3 f  ca% {1 l1 w- ]% A# m5 v7 t: q/ j
  setup-globals( [0 f+ x1 _8 b
6 {) V3 F, M, B" M0 y+ I$ M
  ;; First we ask the patches to draw themselves and set up a few variables
& H. r+ L! Y# S0 J2 X1 ^  setup-patches& Y+ |$ a, F, Y" @7 l" O
  make-current one-of intersections
8 C2 F6 M. i) Z) ?% b, r( }8 R  label-current
3 T# V7 L6 D3 [
/ l. ]: ^' b$ N. i7 Y9 e  set-default-shape turtles "car"9 M, M  W' L/ o( e$ k& b

8 e/ q, c" O9 B1 [, C2 F, {* L  if (num-cars > count roads)4 [8 K2 K5 k0 _! w
  [  ~( ]( D% k6 _3 q2 @% E
    user-message (word "There are too many cars for the amount of "- g, z! X, k. m8 d5 }# z
                       "road.  Either increase the amount of roads "
) C# s6 p" z+ E/ S$ Q                       "by increasing the GRID-SIZE-X or "3 K9 H. A! |0 E# m, m, B/ ^
                       "GRID-SIZE-Y sliders, or decrease the "
) x2 E- J4 B$ P6 \( ?                       "number of cars by lowering the NUMBER slider.\n", F# s+ H) V2 |/ h
                       "The setup has stopped.")5 P0 Z* J' K. G3 T; ~+ ~' W
    stop
) X6 \( J3 l% k, Q  e  e  ]& \* F% I, J+ f( v& t( A

' N+ _& F) B/ D; {5 C  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color% G, S% G1 u! l% L/ Q9 M6 X
  crt num-cars
, P# C7 s$ W; K  [3 L+ J0 I& g: t/ `2 w8 B, n
    setup-cars
, k! t: o) d& _    set-car-color
6 @- \1 ]( R) i6 J# K    record-data; E7 B2 V) A; M! \
  ]
# \, k3 W0 }9 D7 C" h  x& c
0 U; ^$ j0 _, \" C- s3 A  ;; give the turtles an initial speed
( U7 Y9 d3 S2 S6 P5 ~! S6 X: v) m( [  ask turtles [ set-car-speed ]( V( u9 q( y$ a* L
- z& s; p  \6 W& s6 X0 L
  reset-ticks4 Z4 ?' D6 X! C) P( T& `
end" O& I* i8 `* ?- o! i/ Q
3 }; @& f1 {" O
;; Initialize the global variables to appropriate values
# j3 N  d: e8 r3 xto setup-globals
! C8 a1 M. K. ?/ h; h" o& |/ e  set current-light nobody ;; just for now, since there are no lights yet
1 u& L4 Y4 I( Y, w9 n) b% h$ a  set phase 0& [1 u' Y4 d0 x3 E, Y
  set num-cars-stopped 0
5 C: t0 B7 X7 ?3 u6 b  set grid-x-inc world-width / grid-size-x
0 m8 L+ O2 C3 _3 |) }  set grid-y-inc world-height / grid-size-y
2 u' L3 t8 N# I# ?4 ~3 v7 y
" @% j9 P8 T  ~1 h# ?  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary; ]" ^( e6 ^+ L. c$ ~
  set acceleration 0.099
0 h* v$ F  w3 R8 g. Jend
9 [* Z! b8 Y- J* j% ?* O% ?- R; l0 d, Z9 v; F& P& x/ s. _
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,1 j1 d5 `; l5 K
;; and initialize the traffic lights to one setting' Y0 @2 H3 H+ `' U
to setup-patches) \, {% ]' a% V8 s7 ~! h
  ;; initialize the patch-owned variables and color the patches to a base-color
1 ]# {: J5 z: l9 N2 y0 C  ask patches
% X* h$ ~5 `* ^* L5 B9 g3 u  [
/ a7 j: E3 E* A1 e8 _( J    set intersection? false
( t: L) o1 [( S: e  f    set auto? false9 B' E" f. k. v2 H2 \
    set green-light-up? true
3 \$ |: i9 j  [: f    set my-row -10 E$ m0 q; R8 {( C
    set my-column -1
; g  ?) ~0 p- w7 Q    set my-phase -1
" i6 t( V6 ~: _% e% S% _    set pcolor brown + 3# z6 Q7 ~* k& |! M( u6 e
  ]* ^3 k1 v1 i' e1 q% b3 v

; v  x. [$ N1 w2 A# n' L) ^; W  G, c  ;; initialize the global variables that hold patch agentsets
7 U6 _+ A; M  j" K# L! D" O  set roads patches with" R8 C% n* R5 V* K3 t
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 D7 `& Q# u' q2 H' O( Q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 r' C9 F, [4 o( f: {9 H! L  set intersections roads with6 t  ~; {) u/ k' y4 T' h/ ~7 W# L
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
5 Y7 ~. H( E; _) ~/ H' v. V6 r& A8 X    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* L; G8 y5 h: \8 t3 S5 n
8 }$ o2 F, }  x5 a! c  ask roads [ set pcolor white ]
* _  b" H8 t' r+ R    setup-intersections
; K: T, A9 q" y3 t) Yend4 M! E* t) T5 L7 j. q3 q6 k
其中定义道路的句子,如下所示,是什么意思啊?& H( e, P/ n! t6 K( X5 s7 K, U
set roads patches with. r0 a( g" }. \" x! o; r
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 d& k* U7 y9 ^; I! L7 Z& K    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. n* F" t- F  |; ^. u
谁能帮我解释一下[(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0)是什么意思吗?
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