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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。0 d. i& v/ p" N' S
netlogo自带的social science--traffic grid这一例子当中,
) C; z. M1 c% G  A; X1 z4 Iglobals+ @/ g- a" X' C
[
  o' Y9 G' u* {1 B2 m  grid-x-inc               ;; the amount of patches in between two roads in the x direction9 m6 o4 q. ]6 u* x) H! {* B
  grid-y-inc               ;; the amount of patches in between two roads in the y direction- U% a1 {  n% J/ ?$ G4 e  t+ D
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if, t) Z1 O: ]. ?
                           ;; it is to accelerate or decelerate
8 }9 a/ @9 X) ~4 R  phase                    ;; keeps track of the phase3 y9 Q- o: x) V; V( \5 P
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure# S( @8 _- y8 P; i% f$ V; _  y
  current-light            ;; the currently selected light$ H6 m2 P  j% \1 j- c' w

& m% P4 Z) S7 J0 Z1 F/ f  ;; patch agentsets: J" t; u9 G6 s/ C) ]
  intersections ;; agentset containing the patches that are intersections
6 L9 R8 [9 x0 o3 Q% T# ~) z  roads         ;; agentset containing the patches that are roads. L5 b9 B. c- t* o3 z
]
. M' e- v' d, q! p& D* |: s! D4 b& E
0 m) q7 f# K! ?( M; @turtles-own
0 S8 n: j' j- \: h! X[
; F0 ~( k6 N( w2 ?5 I7 z  speed     ;; the speed of the turtle
3 L+ i3 w: f6 j2 I( W  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
0 n4 A" I+ ?! ~; g  wait-time ;; the amount of time since the last time a turtle has moved
+ [3 T% R2 X2 z]& F; x% f6 N5 R2 @8 X5 Y' Z
- K0 T4 Q$ L" x! [( V  w7 x
patches-own
$ ?4 R6 x; E8 R9 b- \[
" w2 p3 ^8 Y5 E2 A0 @  n/ B  intersection?   ;; true if the patch is at the intersection of two roads
6 k* p7 u! T& O  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.: i7 W0 @6 \  V( `9 _8 a
                  ;; false for a non-intersection patches.
" m& C+ N% i, ?- V% D* a) J  my-row          ;; the row of the intersection counting from the upper left corner of the' P3 A8 V, X7 h7 m) G$ [
                  ;; world.  -1 for non-intersection patches.$ _1 u% X/ Q# ^
  my-column       ;; the column of the intersection counting from the upper left corner of the
" o- ]3 j; E7 R* |2 I8 `1 m                  ;; world.  -1 for non-intersection patches.
2 F2 t/ y7 F& q9 R5 Y. L. a  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.2 F1 ^5 m% f0 U$ n  f* X5 Y% s0 v
  auto?           ;; whether or not this intersection will switch automatically.
/ n! \8 [  {6 N2 G                  ;; false for non-intersection patches.; r' s# b" v2 w) B  D
]& L4 Q% i% K0 k$ M

2 q/ k+ l3 C5 K9 Q6 H3 Y4 p3 _+ W( H9 \4 i$ g3 z& O7 [4 F5 ~
;;;;;;;;;;;;;;;;;;;;;;
. d1 I3 o1 S& J3 b$ t0 w2 u;; Setup Procedures ;;
5 g3 e. A5 `' r* B! r;;;;;;;;;;;;;;;;;;;;;;# F/ r4 y! Z) w3 M- L2 S

5 L( Z) B! r7 F5 }& [' R. |;; Initialize the display by giving the global and patch variables initial values.8 V+ ^* O  y5 b  _1 U" v- {: g
;; Create num-cars of turtles if there are enough road patches for one turtle to! l" m% l7 g* h
;; be created per road patch. Set up the plots.
: f" X- N: L2 R% y3 Cto setup+ g0 Y0 i1 b. `& v. I  M# Y+ c
  ca
% V/ x" q- p, u1 q6 V/ n  setup-globals9 a: a& d7 Q; q- k* i& |

  F4 Q! a) l$ A. f; E5 A  ;; First we ask the patches to draw themselves and set up a few variables
1 _! V0 V8 y. b  setup-patches( e8 U4 t8 f) L' U- r8 m
  make-current one-of intersections0 L, B" F/ t) {( ^. Y- f8 p3 s5 A
  label-current
- l: Y! D" V$ E. E" _  e& _
/ B+ x1 S/ y4 Y% T6 Q& Q. V  set-default-shape turtles "car"
7 }3 @- J" c" l0 T
$ V  D7 d. `, J+ M0 _( J+ w, i/ m  if (num-cars > count roads)& N- @/ @% n# M; c
  [
* P& c( \$ C, a; O& o    user-message (word "There are too many cars for the amount of "
. m! B8 K, k) N( g+ Q" B6 ?                       "road.  Either increase the amount of roads ": Z/ o3 r) H6 c# N( @5 e
                       "by increasing the GRID-SIZE-X or "6 J6 T1 c  y5 \1 c" M
                       "GRID-SIZE-Y sliders, or decrease the "' R3 [1 |; Z- x, C7 U) m
                       "number of cars by lowering the NUMBER slider.\n"
$ }  q5 M# G9 a" l. m                       "The setup has stopped.")! Q' O% r% L$ S+ D
    stop
! Z; S: m: |/ |  [# D* q  ]
! @4 a% L) D! }/ o; L1 o- ^. r  b" @1 c9 \1 U) ]. [* i+ z
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
0 i2 W& t' s/ L0 U7 _5 h  crt num-cars
! \# |# H/ ^! P  [. E% x" A" v* G* F! f7 j+ t
    setup-cars
( Y* _- j9 y9 `- s; o$ P    set-car-color
, ^% u: ~+ U' C4 S+ Y# o    record-data0 b3 e4 M2 G% x3 x% J- V
  ]
3 P: [4 T* a; s" a7 @( n- g. k* C$ Z4 P: m& ^/ W/ ^5 k! b7 u+ u: v
  ;; give the turtles an initial speed6 Z' r7 x/ y' L
  ask turtles [ set-car-speed ]$ y% c. g* q* c' y2 h

& c: n* c+ X# o% L  reset-ticks
# i+ G; W0 {, [2 }' A# l3 Vend
7 v2 v2 [& P# X# c5 b3 {+ l9 W( x9 A" I1 a9 j
;; Initialize the global variables to appropriate values
' c( _* v* r0 g( Y- G8 jto setup-globals, R! W8 b2 s- p) j. P! @5 y
  set current-light nobody ;; just for now, since there are no lights yet
: n$ h: n0 S: _. [3 e3 ^" e' q  set phase 01 }9 V+ M6 ]. ^5 \. B
  set num-cars-stopped 0
- `% W/ h$ ?9 G0 x* I  set grid-x-inc world-width / grid-size-x+ V0 q7 l+ O3 T! ]/ D, N
  set grid-y-inc world-height / grid-size-y3 J% W( ^$ w% D2 p% O# R1 m

$ w$ W4 y" G2 q9 C9 R/ o8 m/ P  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary) o. ^+ A) ^' V+ u. S) [, @0 i
  set acceleration 0.099
: G% G' I# p" P2 R3 Pend' v, |! I5 q2 s1 L- i8 l5 q
; ]+ x$ }. {6 a6 s
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,+ m$ y+ ~' B0 ~& v" k
;; and initialize the traffic lights to one setting; m! @% k% H5 h: W7 K0 e- W
to setup-patches
# [5 E9 C# i7 U: d9 P  V- O6 }  ;; initialize the patch-owned variables and color the patches to a base-color* l: E- k! K& K/ e. `' K4 M" \
  ask patches; x' A/ i7 J: T- A  x
  [
% ?, G9 u: v- d3 K% w. @) R. Y    set intersection? false
6 A; H% i9 N0 b! |! b    set auto? false
; ~: e- u3 u9 r/ a3 j3 z    set green-light-up? true2 N1 B" M( `- D7 X  J# w8 y
    set my-row -1
+ O8 l, f, n4 V; j    set my-column -1
2 M. K  n1 H+ |% W    set my-phase -1( q+ O# m6 {) |$ D. {
    set pcolor brown + 32 U2 B% j. s4 n9 Y4 X- S2 i
  ]1 Y0 R; O7 l. i

3 a$ R" i! f4 n- l& Q% y  ;; initialize the global variables that hold patch agentsets
" f) i) b3 E& [; F; z  set roads patches with# @2 n" y$ u: a. o9 |7 U7 l" s* [
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! ~8 K) ]1 {" |, N: C8 K3 J# e0 h
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  N6 y  [* x# D+ C9 i0 _# d% V3 {  set intersections roads with
0 Q6 f+ C8 }& g+ ?, g) l    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and- Z+ W! E# X1 ?; F
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; S" l4 G# K8 s- V2 S1 F
# M1 _# `  w, x; i
  ask roads [ set pcolor white ]
+ t9 q9 s' K' c6 Q4 ~! |    setup-intersections
' _; d9 S" X) P/ _% w1 E  nend5 q7 D4 \  S+ q) x
其中定义道路的句子,如下所示,是什么意思啊?
, A6 \. X' ]% o) ` set roads patches with+ U* \- y5 y* j5 {: O# _2 F
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ ]! `2 N: ?9 i/ V* g
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ s! V8 _' J8 G" L5 Q: 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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