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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。
1 G. p. Y- C. j& o' j" anetlogo自带的social science--traffic grid这一例子当中,
* a6 `8 g$ T; Q" _' e( @globals
1 r' T) O2 v) }8 O8 }[( N" e' @" H% J: R7 ^% B) ?* D; N
  grid-x-inc               ;; the amount of patches in between two roads in the x direction9 ?+ f! |) D4 w1 w  E
  grid-y-inc               ;; the amount of patches in between two roads in the y direction4 x% [$ t1 n9 [/ {
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
+ O; V+ s+ K8 K6 T% r                           ;; it is to accelerate or decelerate
  ^( K7 p8 q* e: q4 R  phase                    ;; keeps track of the phase# i, N5 G% i7 Z- N4 Z  [0 S
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
! ?2 W& x  Y0 [; H( [% M% K  current-light            ;; the currently selected light
4 g+ c* s* r# [' ]$ X* q& L7 V7 V/ m0 B% C/ y  M
  ;; patch agentsets
. l+ {9 V! ~& l3 d  O3 w  intersections ;; agentset containing the patches that are intersections
! \& L1 M- U3 [0 X! ]& X  roads         ;; agentset containing the patches that are roads' [9 D" _( H! F  |4 Q
]* t$ e: p5 t  x
  Z% e; V1 x4 o8 Z& {6 l1 g$ M2 j
turtles-own- y$ {9 T! {: ^4 a4 X8 T& ]2 t' I1 V
[
; E9 ^+ Z% `1 ~5 c5 {  speed     ;; the speed of the turtle
; f# s! J% N) z+ e3 b& I  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
8 |: w, A$ V, h3 q& o% t0 F" e  wait-time ;; the amount of time since the last time a turtle has moved
" O2 n0 Q" E, I6 g]9 Q8 F1 W" f5 l5 q: m" P( Q  ^
, N0 N7 L" K% j& R$ B& m; @
patches-own
2 [! k8 B: e) P! g[
6 t* d) o* Z  E0 W7 u: w) `  intersection?   ;; true if the patch is at the intersection of two roads
+ q/ j5 F! i7 q3 N6 z2 [  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
* p5 T$ X/ p+ V- @                  ;; false for a non-intersection patches.6 i& s* ~8 C0 _/ K+ I
  my-row          ;; the row of the intersection counting from the upper left corner of the
8 R8 c& N& j4 D" p# o9 T" @! r                  ;; world.  -1 for non-intersection patches.
6 Y: p" t( m: Y1 E) u# N# z1 {  my-column       ;; the column of the intersection counting from the upper left corner of the, [+ S5 w7 J0 a2 x
                  ;; world.  -1 for non-intersection patches.( M* L" U# C. T" j2 j1 e0 Z1 d
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.' O1 W& m4 J: E# f+ W
  auto?           ;; whether or not this intersection will switch automatically.
4 U( p7 k3 Z, U) f1 R                  ;; false for non-intersection patches.. \6 Q4 f" J9 p, t  X8 b
]
, S" |/ {: K9 C0 l" S! c8 Y: n( l# ?
; |3 p7 P" @9 g3 S9 L
;;;;;;;;;;;;;;;;;;;;;;+ w! J: a3 s- p/ v7 o
;; Setup Procedures ;;# N; X( E5 b- h$ w
;;;;;;;;;;;;;;;;;;;;;;
' R- F5 K, c3 T3 V6 p' t$ z8 b  F, U. B4 w/ t# u
;; Initialize the display by giving the global and patch variables initial values.
$ J  O3 I2 Q/ F) v3 k: s; x;; Create num-cars of turtles if there are enough road patches for one turtle to2 s4 f' r  j# ?' l: Z7 s
;; be created per road patch. Set up the plots., Q: g* c1 d8 V, ^9 L# W, V+ h
to setup
; b: o! a8 v. b  ca
1 k3 ~  a0 h. q' z% N# ^3 H  setup-globals  o& Z, k7 D" _  c2 ]

# M! \$ J2 ]: |: `, w: M  ;; First we ask the patches to draw themselves and set up a few variables
7 ], J6 }! o' r0 \9 ?% j% Q  setup-patches3 N5 L  M7 \1 s; I9 a. P
  make-current one-of intersections. c: G* D; v* r9 H9 R
  label-current/ y, y1 i$ x: L; T
3 Q+ H' I& u% J4 N% w3 F
  set-default-shape turtles "car"0 `8 X' M6 a6 L( T: Z; J2 u
/ R+ Q/ n, Q0 {) o+ p# e  E; h
  if (num-cars > count roads)
8 L0 Z4 g4 |8 J" n! ^  [
& y( `: T/ w3 a' X5 y; X    user-message (word "There are too many cars for the amount of "
5 r: [: ^4 H" Z0 x% z                       "road.  Either increase the amount of roads "9 T; `$ m: x5 t+ x
                       "by increasing the GRID-SIZE-X or "0 G. l2 n; N* L, ]  Z
                       "GRID-SIZE-Y sliders, or decrease the "
/ \  U2 M8 c, @% R                       "number of cars by lowering the NUMBER slider.\n"
8 W% i7 E2 c) p, P                       "The setup has stopped.")
& z3 Y; ?3 y5 ?' {1 ^/ J    stop# K7 {6 I7 [& s. [# T4 |
  ]
3 ]: z- F6 c5 Z) q, [2 Y% K4 F2 `. k/ j, B
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
1 a: y+ o2 v/ @. H* x" S  crt num-cars' s4 \' R3 q6 t& G
  [
2 m" R& u5 i4 a5 \) u    setup-cars
$ [5 \* ]9 x+ y& s2 \2 N- h    set-car-color
! ]; k. f) l- W# W    record-data
1 ]! O7 Y6 c7 ]; P4 t  ]! j, z9 }8 C7 T6 C; B3 ?' ^
7 X" U; r7 D: y) \& E
  ;; give the turtles an initial speed% [' }5 A  U- x4 q/ Z
  ask turtles [ set-car-speed ]
6 W/ E& P* D) c0 M+ [) @( h- \  D2 w/ w
  reset-ticks$ Z# Z) ^" Y9 z9 H4 a- i) `
end
$ ~9 W, S7 \. l5 ~3 x& p; e, @( _' B2 _
;; Initialize the global variables to appropriate values
; ]  Q7 I0 F# Q$ f4 `* A: b) r; Ito setup-globals4 o. Q! G6 T& c' C& y7 @, e; j
  set current-light nobody ;; just for now, since there are no lights yet9 Q1 I8 w/ ^* {0 }. l
  set phase 0
; L4 K9 i% m" K) e  c# w/ z8 k- R: K" d( O  set num-cars-stopped 0# j) T/ f% U* `7 Z6 H. A* D" q
  set grid-x-inc world-width / grid-size-x$ V% ~8 f+ O! J$ K+ f" {- C7 N! |
  set grid-y-inc world-height / grid-size-y
' s5 O2 l$ U( H& C$ D& Y6 U
9 v# R( j) O, D9 Q3 G8 B4 m/ P' G# ^3 x  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary/ Y: c- A& J+ N
  set acceleration 0.0991 C4 x3 |; ^+ s
end
* j; R, f3 I* L- r/ l' H0 ^8 y+ y8 v7 i1 |
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,2 j& u7 t4 D0 }# m( }
;; and initialize the traffic lights to one setting
4 }0 n  u& x6 }4 Mto setup-patches. L8 |% S2 m& N3 Y
  ;; initialize the patch-owned variables and color the patches to a base-color
6 d5 u+ @6 ]$ o/ [% S! t  ask patches7 o- x) s  u  Y
  [
, u* q$ A" b8 y( T3 o( D    set intersection? false
: b. P' W2 o( ^/ L$ A% R0 N    set auto? false
/ q) z7 P! [- Y0 Q7 {: l    set green-light-up? true
& _7 x7 U" @. y% E; z+ \, Y    set my-row -1
* [$ A4 v! d- F# `0 g5 H) C8 ?    set my-column -1) k" t* `. T' b' a" U. G: `) w- e) \% x
    set my-phase -1
$ F4 p, x  e3 o9 _; ?$ S9 ?# d( z    set pcolor brown + 3
0 e+ b4 @& y4 c- ]: r, m6 n: |  ]9 o- ?' T. |* m
0 C! q. v6 m# o
  ;; initialize the global variables that hold patch agentsets. o/ \9 Y0 t3 R9 k% P5 P/ D
  set roads patches with' E1 ]& M, P2 r  C9 j/ H, I
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" D2 d8 ]- j3 s7 ~6 i# E& F    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 V" _, [. X' M! a: v, ~  set intersections roads with
; [! W  j+ {1 F$ {, D: o! s0 D    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
7 {7 P, {: B( m' \    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 d* I; Z7 ^3 I

4 V' G4 w: f' n- c. r; u5 v  ask roads [ set pcolor white ]: g  _) U  N! _# L3 E
    setup-intersections0 E3 J: c) m2 x/ z4 @4 B/ V; I" N
end5 m, ]9 O2 K, M, r% F) V- P
其中定义道路的句子,如下所示,是什么意思啊?2 f& n: H: P5 L; ?
set roads patches with# N0 l( y( G9 b+ E# i" N! F3 p* |
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 M4 S7 `  U; f' h
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% @9 K) J" }4 m. ?4 B. q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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