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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。
* B. |! m- T% p  Bnetlogo自带的social science--traffic grid这一例子当中,
2 t  {( }# r$ B, {1 _9 Cglobals" b1 c  N2 f) M9 t+ E0 _
[
. e4 q3 A" X  ?0 r: `' e/ X; m* w8 Q  grid-x-inc               ;; the amount of patches in between two roads in the x direction
3 j0 I& {! L9 O0 p; z4 i  grid-y-inc               ;; the amount of patches in between two roads in the y direction% _( K# w7 u1 R3 c8 o  t( `2 S
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
; g* C, p# x* ^% i                           ;; it is to accelerate or decelerate
8 F9 u3 Q) {6 Q8 T  phase                    ;; keeps track of the phase$ x- I! r% x8 V$ j- t" I/ s
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure& K3 r0 j0 j& C6 O
  current-light            ;; the currently selected light
7 G0 ]9 X8 ?0 N$ \$ g8 \* I3 f- F' S
  ;; patch agentsets
1 S# z  Q9 l2 M1 j* W  E4 @* D  intersections ;; agentset containing the patches that are intersections
6 y3 |/ E$ a% s5 p0 B  roads         ;; agentset containing the patches that are roads: F# }4 J' ?7 y% Q' J; C4 J' Z! ?
]  s- R* R. `. W- x& A; j3 V

+ l  V  l8 V' Y) ~3 kturtles-own
# _8 V& U( }( d2 @4 m[
/ w" w4 I( c7 _  f6 `  speed     ;; the speed of the turtle
/ n  I* S; z' j# ^# b; F& f: b; g9 L  up-car?   ;; true if the turtle moves downwards and false if it moves to the right( W, ?7 K( `7 J' W% ], v  N) k( z
  wait-time ;; the amount of time since the last time a turtle has moved
! Y8 d$ ^! s& H3 r' o3 d5 {  ^' `]
6 e1 ?3 B0 o% U$ w$ c3 _( Z7 ?: I) v1 H
patches-own
- G& N9 a$ L+ {* d9 e) ^' j9 {  p[
" G  z6 d1 w2 K  intersection?   ;; true if the patch is at the intersection of two roads
' M6 l) D. K. g# R+ p7 _1 P5 }  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.$ V: ~  \4 S! N4 m8 h: I; P$ y
                  ;; false for a non-intersection patches.1 A+ g* j1 d# ]$ I& v3 L& B
  my-row          ;; the row of the intersection counting from the upper left corner of the
: P; ?5 ]* o( V, U4 h/ u/ O5 k                  ;; world.  -1 for non-intersection patches.
0 ^  G$ a( V' Z3 P1 r) d. V5 w  my-column       ;; the column of the intersection counting from the upper left corner of the
( Z3 v8 {" r4 `/ ?, o                  ;; world.  -1 for non-intersection patches.
0 x& P! q; i! D4 I  g: s3 \/ R  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.( r8 D6 G' r. Z# S9 B* Q- ^2 [8 o" i
  auto?           ;; whether or not this intersection will switch automatically.
# c% l* U4 m/ }4 a5 c                  ;; false for non-intersection patches.$ R" `5 }8 e/ `8 P% B# r/ L' F, y
]) E9 y3 N7 ?; d, b2 g( ^

$ Y% ^4 _0 j5 W9 V% v4 R9 `# M. t* W4 s7 {: x8 {
;;;;;;;;;;;;;;;;;;;;;;; Q* F* o( W  w/ K; w
;; Setup Procedures ;;1 x2 K/ p5 h0 Q1 M1 t  d
;;;;;;;;;;;;;;;;;;;;;;' e' U, X3 H2 Z! v

# m- ]8 O" ^7 J;; Initialize the display by giving the global and patch variables initial values.9 N: v: ^5 a8 ^
;; Create num-cars of turtles if there are enough road patches for one turtle to) D& z8 L* G; d
;; be created per road patch. Set up the plots.
( d( M4 E/ @" d! c) ]to setup
2 |! r# k2 @9 k  ca) }) @8 P# T! x3 ]- z
  setup-globals: y/ b3 E( i" P! E8 v4 O3 g. \

3 s; f3 ^9 l* b  ;; First we ask the patches to draw themselves and set up a few variables; p, c( e/ K5 \" Y# Y4 O  v3 ?
  setup-patches
- w( l, K$ E4 C8 e4 t+ Z3 q9 l6 h  make-current one-of intersections
8 D% D4 n2 v% \- ]% a  label-current0 F$ u& z' C6 r7 m& D) @7 Y, F
5 U! g; u) r' \( Q
  set-default-shape turtles "car"
0 a7 C  W6 Q+ Q) l+ ]5 V5 Y5 j4 K: f. ~# J- `& E8 M
  if (num-cars > count roads)
) `/ X* }3 u( P2 r" L  [
! G- T9 v" x7 h% |# n( E, `0 t( B    user-message (word "There are too many cars for the amount of "
6 t' y( B# R) H                       "road.  Either increase the amount of roads "
2 B* n3 l: k9 v5 K9 Z, T# p* x, h" J                       "by increasing the GRID-SIZE-X or "
9 ?# z, B1 w, h. O                       "GRID-SIZE-Y sliders, or decrease the "
. V/ t, L4 h  ]$ C+ A9 l8 W                       "number of cars by lowering the NUMBER slider.\n"
8 p/ _, r" Y, s                       "The setup has stopped.")
( X9 v) u- k# ~& ~9 Q4 {& w' ?6 p    stop% y' e/ i9 ^$ i
  ]4 o, J! Q; f" S# A
# Q$ h+ N7 {& Y" v/ Y7 C
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
( d1 J" H$ k7 z  crt num-cars) [. R, G9 j* u7 f5 @# ~
  [
9 C* ?% N5 z& Y6 [2 ~# \: T4 r    setup-cars1 K2 `2 F9 s* Y( w; i
    set-car-color+ ]  o4 x; c. `" |2 a$ r6 P( c, R- g1 V
    record-data1 l* G) j1 B' ]( |0 I5 v; k
  ]) E5 R: G7 Q0 a! e$ H4 o
9 G; @- L/ w5 a3 a+ m* E
  ;; give the turtles an initial speed/ D$ s; l# }1 b) n/ [7 Z
  ask turtles [ set-car-speed ]6 g( e/ ]! ?& m2 q

* S$ ^) k* e' X0 c  reset-ticks  L- r3 o9 l5 ?3 b, ^; W
end: [1 U8 ?0 T9 O, L
) O1 k0 X7 p% }) g( r6 F) r0 ~
;; Initialize the global variables to appropriate values
* W7 N: J$ j6 G: x4 `- `; {6 h/ f2 }to setup-globals, ?5 Z1 K) [8 S! \+ I
  set current-light nobody ;; just for now, since there are no lights yet5 l6 g4 p; k( J! e7 P7 B$ X- P0 g* \
  set phase 0, [! n6 c2 X8 d0 j# x
  set num-cars-stopped 0
0 Z" N, S4 Y' I& U  set grid-x-inc world-width / grid-size-x
6 Z) v" L5 y$ z" \1 q  set grid-y-inc world-height / grid-size-y
) d, F) i; v' m0 H, O/ S, o  @9 T- K
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
- a, W1 |+ X1 E  set acceleration 0.099
9 Z" J& ?) G1 u7 e. m5 nend: j. M9 v1 }* ?# Z" W1 B
+ [( M5 |% a7 \* E7 P- k
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
3 C3 `$ [0 `8 Y& @: {! l+ o) \$ w;; and initialize the traffic lights to one setting
0 W; t& H) P! h7 n* wto setup-patches
0 U$ H3 d1 d) @9 M; R/ x  ;; initialize the patch-owned variables and color the patches to a base-color) V4 v& R3 V" L/ U$ L8 X
  ask patches! b' A. E  p4 D2 X
  [
7 V! w% h2 C, }7 o    set intersection? false# Z. u) i( d2 j8 ^; \
    set auto? false* k& C& S3 l0 h" Y8 T* U
    set green-light-up? true
0 Y0 G3 R( Z! ~5 {4 A7 a    set my-row -1
% Z- J- }# x8 g/ d5 n/ i# n    set my-column -1
/ \" y% d  {1 L2 y) `. Y3 D    set my-phase -1
$ U! p7 h: g( |. u; p    set pcolor brown + 3* U: G2 c: u( T+ W& Y
  ]
/ M& e3 U/ ^6 R0 l/ W: I5 `" H% P! B1 |+ H; x4 X5 N1 D3 N
  ;; initialize the global variables that hold patch agentsets# [; X; j" W& ~* f8 g
  set roads patches with
2 M# W  _  [! r1 N, \: _    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
  ]& y- K" ?4 P    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! A; \3 `5 U, A. Y4 I0 A8 v
  set intersections roads with
  }  @' ~( U  l& k' L    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
" j2 j- l6 m5 e    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 ^! C: c# C+ t' z$ ]

6 [( {9 y! x7 J; ~  f: Z, h1 [5 S  ask roads [ set pcolor white ]
0 |! E9 n4 b  ^) a5 @  y    setup-intersections
1 A+ m( G6 g5 H7 pend$ d! O3 e) [- e  L* y, t& M
其中定义道路的句子,如下所示,是什么意思啊?: J4 J" K# G9 X# _
set roads patches with
9 c" q, I0 j) Y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 y0 v1 N) R0 A, S: V    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& |6 [# A' F* ^0 H* ~0 i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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