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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。
! Y3 Q) F! ~  _' m/ unetlogo自带的social science--traffic grid这一例子当中,
. r' }/ S# v. {) p0 \globals( P! I, y. [6 s  ~
[
! u$ i2 B, x0 N: x0 q  w% y8 w  grid-x-inc               ;; the amount of patches in between two roads in the x direction3 X: Q* u9 k& P8 ]5 d5 V0 S2 R
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
  P4 U4 q2 V- G  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
+ `7 V4 @& ~& N) f" z$ n( n                           ;; it is to accelerate or decelerate: g' Y3 n' c' R, g9 H( d% O0 w1 Y
  phase                    ;; keeps track of the phase3 U# }- j7 C8 F, E
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
% T* R4 {, z' k0 N6 X- |$ y  current-light            ;; the currently selected light  C  {* ?/ m1 q3 O( U! \
6 V4 {, d- n+ u! o
  ;; patch agentsets4 e1 L, C; \. F8 Q5 I8 ^  G
  intersections ;; agentset containing the patches that are intersections$ H1 I& I" B& p0 b- F
  roads         ;; agentset containing the patches that are roads
8 r' m' R/ K7 \' _9 L2 R]3 N5 m( w( M4 y* P2 v. x+ B' h; a
: z* G6 [) j/ Y
turtles-own3 X7 P4 L" |0 p% P5 E; l3 N
[
0 W4 S2 C3 \) _  q. v# n$ [  speed     ;; the speed of the turtle
/ Z5 A! x  H/ ^9 W; V  up-car?   ;; true if the turtle moves downwards and false if it moves to the right5 G& m; O& c7 x& y1 w. X; Q' _
  wait-time ;; the amount of time since the last time a turtle has moved, m2 Z4 D3 j2 J4 u2 G; T4 V
]0 n0 t0 L! b4 v
, B$ C3 W3 s8 O- [+ x/ c& B. D
patches-own7 X( ^; v8 f9 r* t) N
[
- t) A4 l# F1 W' t" S7 i# z  intersection?   ;; true if the patch is at the intersection of two roads
, \" G1 Y/ C: H8 P  green-light-up? ;; true if the green light is above the intersection.  otherwise, false., Z' M( d0 f0 K3 m% b  M- x+ ~, u$ N
                  ;; false for a non-intersection patches.: X: d& X; U( a, o1 n8 X
  my-row          ;; the row of the intersection counting from the upper left corner of the1 W# F. G) D! o. f9 S" R4 W
                  ;; world.  -1 for non-intersection patches.
" g4 p& _- P  a  Z- h  my-column       ;; the column of the intersection counting from the upper left corner of the
. f0 J, x. M4 m8 W5 H) x                  ;; world.  -1 for non-intersection patches.
. r  N1 f$ x* Y% b9 v  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
1 `3 a2 L/ u: ?  auto?           ;; whether or not this intersection will switch automatically.
, f$ n  b) J0 p0 r' `2 q1 V                  ;; false for non-intersection patches.$ [* q( W+ d; k/ g0 O# A6 j) A
]
; n' p: l$ g+ b9 H1 d: ]
8 |) I9 t9 j* m3 |  y" J% J# z. z2 l6 J/ ?% j# B" o
;;;;;;;;;;;;;;;;;;;;;;: ^; z- h6 N5 g, `
;; Setup Procedures ;;
, n, ]# E) R4 a9 m0 {" {7 A;;;;;;;;;;;;;;;;;;;;;;
" g( o  Z2 `1 Z8 ~0 O
; J4 W$ U. D" D" R' d9 U) s;; Initialize the display by giving the global and patch variables initial values.
$ o; Q$ Z: }% Z;; Create num-cars of turtles if there are enough road patches for one turtle to
8 N. F6 [8 Q, X' B8 d) L7 E6 e;; be created per road patch. Set up the plots.! v% f4 X& Q, s3 `, `/ P5 r
to setup
4 b  T- u! J6 T' e) D1 m- p6 o  ca- l6 R$ Z4 k: ~1 K
  setup-globals
7 l7 X7 w2 Z* x5 p2 p. m# j
6 W0 L7 |; T3 [: z6 c  ;; First we ask the patches to draw themselves and set up a few variables2 {7 m: P9 }4 i/ m; {0 G
  setup-patches* J% U% |8 U2 y" |1 `
  make-current one-of intersections7 E: G' P6 h9 x0 ~4 O- Z
  label-current
" D' Q6 t4 P0 Q- G3 Q9 @8 ?: T( {
  set-default-shape turtles "car"
; N+ U2 e! d0 B; k: S9 ^# s* g& a! h3 [% Y) f# e% X" Q! ~+ G) s# {
  if (num-cars > count roads)" C8 v. G- @' R  M3 {
  [9 D- L, B* U8 W( ?2 L5 \; p
    user-message (word "There are too many cars for the amount of "
7 C0 L! z* `! W) w                       "road.  Either increase the amount of roads "9 `( d+ h" p2 o9 Z/ s9 G
                       "by increasing the GRID-SIZE-X or "
# b. w/ T$ e6 Y8 B7 j2 C. r5 c                       "GRID-SIZE-Y sliders, or decrease the "2 j# \/ Q9 p  G$ I; V: X' X! G
                       "number of cars by lowering the NUMBER slider.\n"/ b; T1 C. w" M1 U% A' t0 \
                       "The setup has stopped.")  X9 w1 d* T& s
    stop4 `/ S- a1 O3 k
  ]
' x( T' t- d* Z  J* N- m9 V
4 s7 k; n+ s  X& b9 ]0 f/ u& ~9 H  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
6 u# s2 J6 U! [" z9 F( Z/ }  crt num-cars2 L. e; P; ~- ], O
  [
0 _4 S7 q6 _9 w* n) J    setup-cars
; Z2 m# P* L+ t: ~3 \% }3 ]1 O    set-car-color( k* q' p. Z: E" V% _9 W
    record-data
; U- R6 u" m7 ^) X  f- @9 q0 T  ]5 c7 s/ u) Z4 I0 T# j# k0 R2 n7 T
+ z$ Z! O" T9 m
  ;; give the turtles an initial speed
# i- A6 S( |/ u. f- \5 ?  ask turtles [ set-car-speed ]
# |  E3 g; ^: Q! @& q: t
5 x) g' k# I' k& E  reset-ticks$ f4 w( S! ^. ^9 u+ T& z
end; R" \8 R! Q0 D5 c( _/ C5 l

/ [6 I0 D, ~2 \;; Initialize the global variables to appropriate values
$ [+ x: L& H7 B* q. F) rto setup-globals. @/ ?, }  Y3 k' A0 M' {
  set current-light nobody ;; just for now, since there are no lights yet
6 O8 W! r+ g; }4 a# D  set phase 0* D% A- H% k9 b3 u: j
  set num-cars-stopped 0, |3 r9 B% U! M* N8 z5 J, b
  set grid-x-inc world-width / grid-size-x
# w3 M$ x& i" F* c* v' S3 M1 E  set grid-y-inc world-height / grid-size-y: H* X% [/ K3 o

! p. i0 A# ]$ v/ `! u6 @7 H) P  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary" p8 K6 U/ u; V* B5 |/ W9 V/ N
  set acceleration 0.099
$ ^' q( }( C; o) O' wend+ V/ S# u4 _; s, Z5 o+ D! c
: M" G6 w5 h8 ^* E& X$ h
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
8 f+ R% K3 G) {5 k;; and initialize the traffic lights to one setting
6 H( O+ y" g/ L+ F5 f- F: y: Cto setup-patches
( _: ^0 |  p4 d8 B) @9 _9 r, q  ;; initialize the patch-owned variables and color the patches to a base-color
3 S- [$ v7 Z9 [& C- V* ]  a6 C. P  ask patches
, T, `6 w; k2 M6 R& g7 w: V  [& H: c, k" K( u5 g( p" T
    set intersection? false, q! p, y5 r5 U  {7 n! l. _
    set auto? false
6 f. B! f5 B) X( ?8 a+ x7 R    set green-light-up? true
" J; B6 D2 t/ e9 A$ K- P: Y5 r% R    set my-row -1, [6 }0 V  h3 B
    set my-column -1
- F+ F: S4 M6 Y6 `    set my-phase -1: @; ?& x" K% u
    set pcolor brown + 3, }: ?0 S! K- B4 z/ D( p  d- p
  ]
$ t0 z: k6 c& K9 i! Z+ j, _- L3 a: w# S5 h% l
  ;; initialize the global variables that hold patch agentsets
1 `- M, R: n# q- T  set roads patches with! |$ ]# Y) E: o9 Z& T: ]+ o
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 k! H3 R; F1 I( S8 K. s
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" w- {2 t. S+ s" d
  set intersections roads with
8 r3 _$ R9 s4 f" i7 v    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
+ U# t* D" }* z# q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ O9 G) H1 U- w' s% x# O9 \$ ?

) U" x; v  O4 M" h  M4 }  ask roads [ set pcolor white ]  c) Q8 U! a0 V
    setup-intersections* M6 x. Y( N' B$ _9 ~( b$ ~
end
, ~1 M- \. ^$ t$ i, Q+ F其中定义道路的句子,如下所示,是什么意思啊?( l3 h2 t3 b2 n  x
set roads patches with' w! e/ ]/ o7 v' @: l; X. A
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, m0 a; J' o0 B4 B    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" O5 O8 ?4 x$ i. ?9 }9 ^
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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