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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。4 Y+ s& n* Q) @6 U) ?
netlogo自带的social science--traffic grid这一例子当中,6 J3 z: r0 A0 b" x6 x
globals2 s" O' M) J% G0 A$ p
[' _6 ^3 W/ n  v) G( H- u
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
5 s4 a; Z+ |+ \. z% T  grid-y-inc               ;; the amount of patches in between two roads in the y direction6 @( s2 |9 z) N1 L: U7 n1 q
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
- q8 @. r: a- o" ?                           ;; it is to accelerate or decelerate
8 x+ P/ T7 T* B0 Y9 P5 ~  t  phase                    ;; keeps track of the phase
9 P+ Q3 o7 w5 D( H: i- n' L  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure9 s! `5 _6 r; s
  current-light            ;; the currently selected light
: B  a0 w; k% C
5 U: S- k4 X: B* M, o1 _3 J( o  ;; patch agentsets4 Z- K2 t+ o# B6 g- F' L2 O8 s
  intersections ;; agentset containing the patches that are intersections+ N7 f: k+ _) e
  roads         ;; agentset containing the patches that are roads
0 h$ ?9 y! i" B+ V$ ~- ]]" q3 l$ y. _- m; p+ B) T

- k- ~0 G1 \8 }% oturtles-own$ y9 T& ?9 q2 f) q/ a' O
[" I. x% \6 L) C4 G2 p& ~
  speed     ;; the speed of the turtle
/ L  n9 {+ L- ^9 D( x+ O% O; S  up-car?   ;; true if the turtle moves downwards and false if it moves to the right4 s8 V9 h3 z3 H& K0 i& u, f
  wait-time ;; the amount of time since the last time a turtle has moved- ]/ I0 r7 P3 O! m% h) o  S
]+ o6 ^5 [7 W. N
1 m" o: s! @2 U" }& {
patches-own0 q$ G7 I' r% {5 v8 e2 z2 y* b
[
! G# c$ u" p8 T4 o6 I  d" D  intersection?   ;; true if the patch is at the intersection of two roads
( H7 F7 ~8 D" U: F8 u  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
0 I1 ^4 G7 W5 V, b+ v$ f                  ;; false for a non-intersection patches.
5 {- @7 e+ ^" _: ], D7 V7 P  my-row          ;; the row of the intersection counting from the upper left corner of the7 y7 @+ f1 r4 y
                  ;; world.  -1 for non-intersection patches.
% D6 d  h# K% y0 @. O+ o; [" u  my-column       ;; the column of the intersection counting from the upper left corner of the6 S. ?6 v/ f3 a3 W7 i/ p0 N
                  ;; world.  -1 for non-intersection patches.
5 F4 b4 W4 a" V) @: ~; u  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
4 m) `, r. s- t1 y7 D8 @  auto?           ;; whether or not this intersection will switch automatically.7 f' q4 _: H; a' D9 [. J
                  ;; false for non-intersection patches.
5 Y3 @) v. o, ^, q- A]$ n$ W. I0 O& a& T+ d

( N# P$ L6 b  Y7 ]
* U; S" w5 k* h; }2 \5 a;;;;;;;;;;;;;;;;;;;;;;
1 l1 D( {# h3 o0 @: n" B;; Setup Procedures ;;
$ L# p8 L' }8 Y;;;;;;;;;;;;;;;;;;;;;;
- ]" P, V" R: a# I: n
( H' `. h, p; ]3 V;; Initialize the display by giving the global and patch variables initial values.
5 G  X4 M7 E, ]" \;; Create num-cars of turtles if there are enough road patches for one turtle to9 R# D. i, Z. E1 u  `' X
;; be created per road patch. Set up the plots.
& J: T2 T5 Y" F" [% g1 Bto setup. D+ w' s' [  @
  ca
/ h$ |  T( A2 _6 C" W. p/ A  setup-globals
8 [7 Z. g9 R0 A# h5 g# H8 T
- V* W+ t' q$ _% R' a  ;; First we ask the patches to draw themselves and set up a few variables
9 g# N5 o* B, y; B6 r4 j: A5 P3 U% h/ R  setup-patches
; |+ q' A" |* ~0 }8 k  make-current one-of intersections
: n3 m& l( x2 F! t& S- w( k; \' a  label-current  k4 p' d+ Y8 A% \

- n1 h- @& E7 j1 ?4 H3 ]& v  set-default-shape turtles "car"
' B6 A; Z. k) i$ V# i  `9 v: `* j: L1 h
  if (num-cars > count roads): X6 B: Q$ D# R
  [
2 v9 h' I, ?' q    user-message (word "There are too many cars for the amount of "
$ S- u2 L9 }# P; h8 X: D$ @' U                       "road.  Either increase the amount of roads "
# t0 r0 E  m; {2 ~5 V! ^* U3 ]/ E                       "by increasing the GRID-SIZE-X or "9 @$ h( ~% z$ t0 m7 I6 Q& X- t
                       "GRID-SIZE-Y sliders, or decrease the "
+ {* N; R* c( ?9 |, s                       "number of cars by lowering the NUMBER slider.\n"
! _& d0 \+ r5 R5 |* l) Y                       "The setup has stopped.")( Z! x2 ^8 W8 @) I* _2 s: ?
    stop
  [' n  e, B8 f4 F% W  ]6 A. Y2 D8 q3 |6 K
% F2 z" K9 k# I4 B
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
# e- G4 m: I4 r, J  crt num-cars- X2 E& t/ _! y1 |; K8 J& u
  [; C2 N+ Z, ], g2 R% s) q
    setup-cars3 F8 H! ]* V# T4 F/ K/ F
    set-car-color
& Q3 g7 T! r7 v+ W    record-data1 S" |3 g5 V( A( v& ]$ y
  ]
: d, o0 C9 J( S' E' C' a0 h" ^- s0 U% ^% f" `) K; Y6 B4 w
  ;; give the turtles an initial speed& b2 q& q% D3 K5 Q
  ask turtles [ set-car-speed ]
3 ^% E9 Z& g- T2 |- V
5 Y1 Y1 K& [& V) r  g  reset-ticks
' q% L" Z: s) j4 t8 s) s  xend+ o( t( x+ \4 `8 R% b7 O% W
6 A' H  G$ M1 U. w7 F
;; Initialize the global variables to appropriate values9 o( v; H, Q. B& z5 {/ ~5 L3 k
to setup-globals
  j* l4 l1 }. ?" N& r1 T4 o1 t  set current-light nobody ;; just for now, since there are no lights yet5 V  @6 @; f+ m
  set phase 0  p. [7 t, o5 u/ v
  set num-cars-stopped 0
/ w3 d6 n8 t  c  set grid-x-inc world-width / grid-size-x
/ u" x- j* q+ g# l" p  set grid-y-inc world-height / grid-size-y- A0 _' N6 }8 u% H

! s) [% L) k6 `! n0 U7 ?  v9 n. _  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
$ n. u' [+ z8 @$ W, {& @1 {/ G! F7 V4 k* O  set acceleration 0.0990 d4 i  z. j# p1 G7 `% n
end8 h9 B- C/ A/ ?) [/ N
# `; m& r' W* ]- s
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,/ p# Q! _# D3 M4 [/ A* s
;; and initialize the traffic lights to one setting; C) r5 |/ u) G% q# Y6 K. C) J
to setup-patches8 L- k! ]4 D1 D
  ;; initialize the patch-owned variables and color the patches to a base-color
8 M  i7 ~6 v  p6 z7 M& E  ask patches
+ {9 z2 z, N1 @. A) j" w  [' u6 w' |+ u* e$ M' Q
    set intersection? false
: i. @8 L% ~! Y* s+ i7 |+ p# O    set auto? false  D$ K3 L9 Y- E7 [
    set green-light-up? true; E7 _# X- T- Z1 {8 ?5 p* N
    set my-row -1! w9 \6 y% H5 s& |
    set my-column -1
  d7 J0 E+ N8 S* R$ g    set my-phase -1" o5 r+ c9 `3 D9 S/ _+ F
    set pcolor brown + 3
+ w: {2 b2 ^/ v! \& C& v  h. ?  ]
/ \. n3 S; d/ `' K3 e$ o1 d4 h# g7 R7 b; H3 e: S
  ;; initialize the global variables that hold patch agentsets
! j( y( X% D$ K  E2 a  set roads patches with
2 h; m" x- ~8 M% ^1 h2 V/ m    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or& d- {2 f" |9 u* S7 _
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 K3 l. q) S+ e" H! ~& ^0 Q6 l' W  set intersections roads with
. C7 i: W. y  Z  w+ b" H: L    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
1 R) i) G# g9 R) L: R" i5 T5 V+ }    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 T( F! E) F& u6 I! m/ I

9 R& ~. U% [4 _! y4 l: e  ask roads [ set pcolor white ]* s! B+ l( R  z
    setup-intersections
5 V5 ~; L$ x* A7 t( Z$ _# Oend$ p- T9 y, ?$ n  B6 r1 n3 ?, |2 E
其中定义道路的句子,如下所示,是什么意思啊?8 {, \! O) L$ S* ?! }
set roads patches with
* S  L5 c! c' R4 M    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% W3 e5 d6 i3 G! e; b& Z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 Z" I  E# I( Y5 V
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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