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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。  |/ Y# ^6 n% N) P
netlogo自带的social science--traffic grid这一例子当中,# `9 P& i( u) e
globals+ q+ T) X3 E( A' e# v
[; ?8 x8 P  e4 f
  grid-x-inc               ;; the amount of patches in between two roads in the x direction% T- V& Q; ], x0 j3 l6 ]
  grid-y-inc               ;; the amount of patches in between two roads in the y direction9 c- |5 R$ Q# U4 d4 X
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if2 c; {- \$ v2 f) u# j$ d7 u
                           ;; it is to accelerate or decelerate
4 J, P6 b; k8 V; C# I5 k  Y  i  P  phase                    ;; keeps track of the phase
! a: N2 U0 r5 j  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure# V  u1 Z; b$ K
  current-light            ;; the currently selected light0 F, _) L5 _, v9 J' z5 |/ H3 O8 {
! m4 j. a! `9 [- o9 t  B
  ;; patch agentsets- o1 p2 S- |: i1 @) O
  intersections ;; agentset containing the patches that are intersections
) X6 T( S" d4 I- x6 u1 ^# ?# I  roads         ;; agentset containing the patches that are roads
# Y" _+ u" w" Z- B]: N* q  [+ P1 k9 g
6 ~: G8 o- x: N/ z" N0 V$ G
turtles-own, r7 v5 ?7 B0 Y5 Q; T
[
$ s. X9 |; i5 q! u( Z  speed     ;; the speed of the turtle: u  B5 S& `3 ?/ b5 ~- U
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
& B" y1 v- _) [* ]0 Y  wait-time ;; the amount of time since the last time a turtle has moved
9 q: R6 n0 e- Q- K3 ]+ j- ]]/ b7 p% k& ^2 Q+ N& m

  ]. c# J% O3 Spatches-own; F% V5 `" U6 J; |2 J
[" z. v8 Y7 o7 H0 h- i
  intersection?   ;; true if the patch is at the intersection of two roads; ^0 a( j* z% o* ^
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
1 `4 }% n( V- F# `7 J; Q                  ;; false for a non-intersection patches.6 a7 N) O; o  ~+ c' s
  my-row          ;; the row of the intersection counting from the upper left corner of the
1 }! P4 ?" }) H& G/ B( X                  ;; world.  -1 for non-intersection patches.
1 F- f+ N' i# r+ W1 U6 H  my-column       ;; the column of the intersection counting from the upper left corner of the2 B6 v4 ^' m5 L* w1 {4 `! M
                  ;; world.  -1 for non-intersection patches.
# `1 S9 z9 o- h" Y" v$ Z2 F  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.1 {4 k: r, R5 g. V7 p5 _) `
  auto?           ;; whether or not this intersection will switch automatically.
7 Q8 v' w' Q" p; H8 H7 V                  ;; false for non-intersection patches.
9 H" v8 Y& N) V/ g]
' H. O1 g$ t% Z1 P+ r! n
; |$ p6 _/ `3 f- `  q
9 X9 v% O0 ~. O9 G  ]- r0 K;;;;;;;;;;;;;;;;;;;;;;
1 o& R" Y, L- a+ O, b;; Setup Procedures ;;& E: g2 z# n: ~/ N
;;;;;;;;;;;;;;;;;;;;;;8 A" k3 Y5 a6 ~. a! O/ V/ `
, Q; p: n; I$ \, G0 l
;; Initialize the display by giving the global and patch variables initial values.' Z/ ?7 `5 s3 r3 f( s, y
;; Create num-cars of turtles if there are enough road patches for one turtle to- W  E, p. `# h  @
;; be created per road patch. Set up the plots.8 v) A( ~- k4 x, j$ i, ~
to setup% _' E/ [+ W+ f1 F' s
  ca
+ B( ?& M0 x  q8 }+ i  setup-globals# F" H, ]- ?) p/ I! f" H# `
( p7 t5 A! w, g: ~% k* {
  ;; First we ask the patches to draw themselves and set up a few variables
  e3 L8 z6 M2 P7 I( E, a( N5 [3 g  setup-patches. j# u) t/ Z" N4 L* _" `
  make-current one-of intersections. {: ?" Y7 w9 R) [! P9 L5 a
  label-current. F5 O# F9 J( ]8 }0 m! `
- W, N/ X0 M7 \8 L1 ~/ }# l/ W; v
  set-default-shape turtles "car"+ a+ H2 O  u% Q& T5 U) w5 ?
: W3 ?& }( e$ K3 |
  if (num-cars > count roads)
! {0 @$ c: g% ?! S! g  [
2 f) a, i: D! _$ c; q# w    user-message (word "There are too many cars for the amount of "% v) t/ K; c' a# X5 |; L
                       "road.  Either increase the amount of roads "
  L* K" ^& `) Q+ F- R                       "by increasing the GRID-SIZE-X or "& h- ~6 K6 |6 P/ |2 f
                       "GRID-SIZE-Y sliders, or decrease the "
) `/ T7 ]) c! H: }- V4 t                       "number of cars by lowering the NUMBER slider.\n"
5 ^+ J6 s5 w8 V; V. X; O! r! B# H                       "The setup has stopped.")
( f* U- [1 Z. E( B4 v    stop$ Q. F/ p( x5 H
  ]
* S) Z7 h4 q, j/ j0 C6 ~$ Y$ {8 |& ~: T
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color8 o  f+ V: L+ L- x6 r2 n
  crt num-cars8 m! Z, r3 D  P3 a% V, _% U
  [
: \+ _8 }3 P' u2 {6 P    setup-cars
1 ]; V) _3 |2 O2 X) n4 x0 l    set-car-color# @* W" C" C# J& h9 L/ j
    record-data
4 N6 ]0 h& g. ^: k" b  ]
- s* q+ p: a/ Y& U9 n& n- O) i! ?/ e
  ;; give the turtles an initial speed
8 m' Q% R% y+ R5 ^+ S6 Z' B- s  ask turtles [ set-car-speed ]
9 G1 Q; T  o8 J! k% P5 o
4 {9 S1 ~: G( D1 y4 R( U  reset-ticks( w$ v* L& m6 {( w4 Y
end) }5 c2 h+ I% ]" k- _( N' ~/ o

9 O% D' {4 I' L' m) a;; Initialize the global variables to appropriate values* T' O  r* ?1 [* B* U$ a2 W
to setup-globals
* N1 t9 I' n# D  set current-light nobody ;; just for now, since there are no lights yet* i5 M; _% Z, {! Q
  set phase 0
+ _: P( y9 a$ p( h, m% ?! b8 A4 _) B  set num-cars-stopped 0/ k6 Z: [* F3 [" m; z. q
  set grid-x-inc world-width / grid-size-x# ]& s( p& X+ D  k( @: ~
  set grid-y-inc world-height / grid-size-y* P, H1 Q2 m" E9 a' X# }
5 Z/ V* v: S; U) t  g
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary+ r7 O8 r' N% l: k) `+ Y, L
  set acceleration 0.099
& c8 z5 Y% ~, O- j8 G+ c# J5 l* t0 yend
. a# a: s0 P% q. S, n
* z8 g) ]2 [2 F;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
9 W$ T& o  y( D% i* z) B! Z;; and initialize the traffic lights to one setting
: v- k' E7 L3 G% n" _to setup-patches4 N$ N; q8 b5 e" e4 e2 [8 E' W+ [
  ;; initialize the patch-owned variables and color the patches to a base-color; I1 l8 B. K/ g5 F% t
  ask patches
/ ?- S. X5 A4 |6 c  [5 @' H/ j: Y' {9 \( v
    set intersection? false; B+ _" A+ O8 m& b
    set auto? false' b& t' x/ g2 Z5 |! K: X
    set green-light-up? true+ _/ o9 X' d* h6 D; c
    set my-row -1
# N9 m4 a: g$ H  X- v6 X. O, \    set my-column -1/ v  P6 O0 M8 \/ p; Q$ h
    set my-phase -1
* g4 f, P3 h/ `1 v8 A, {    set pcolor brown + 3: S  t6 A3 i" C$ c6 s  i
  ]8 t' ~: f9 c: B. H8 n

0 y" ]1 z6 G* L3 V- u  ;; initialize the global variables that hold patch agentsets
5 ]$ t1 X% W; G- A( @1 I  set roads patches with' D  t! @% S5 ]. M- P
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 s# Y% S# l9 A1 O
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 v- ~% O$ }: ^7 c: k  E5 S5 f
  set intersections roads with3 L7 p6 C6 n# S. @" v
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and# N1 ~/ j$ ^. Y4 V) I" L  W1 s
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 Z* ?2 s6 B, x2 v. v4 n0 I0 W  g, \, Z7 U
  ask roads [ set pcolor white ]' h3 A- `1 T0 z! {4 n- ~
    setup-intersections
! g% H) r7 c1 F. A" I# k' Vend# C, D9 R0 n! c; i6 P8 a
其中定义道路的句子,如下所示,是什么意思啊?
4 q8 G/ B2 u+ Y3 c& [6 A set roads patches with% ?9 R8 b3 q2 F6 R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ W) F+ R/ J4 F8 M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 {9 S3 Y! I" L  F  h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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