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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。
) U+ i) y- S; ]2 i- |netlogo自带的social science--traffic grid这一例子当中,
$ T4 m, u$ y. sglobals( ^" Q* W/ R. a2 a7 C/ y8 b+ _
[
" P1 U, S1 D" Q  grid-x-inc               ;; the amount of patches in between two roads in the x direction
  x& g) ?" B! X) J: \6 ]7 c# Q3 @  grid-y-inc               ;; the amount of patches in between two roads in the y direction) {7 J- Y8 ^1 Q: p
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
  L& q( s# t# ]# y8 _' [, A                           ;; it is to accelerate or decelerate! _  M% G3 T/ O. Z. Y1 k: Z
  phase                    ;; keeps track of the phase/ v" y- z8 w8 R
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure4 {  X( M  l  ^. t5 H8 m+ G
  current-light            ;; the currently selected light
$ Q  W+ F: q" U% Z2 f6 ?, p
' w& q6 \0 a1 c# G! N( ?6 Z  ;; patch agentsets
% P5 D1 O! \& i! `9 ~  intersections ;; agentset containing the patches that are intersections" P# |& b) P2 g$ @7 u7 W
  roads         ;; agentset containing the patches that are roads
) n2 s8 c6 J! p5 e6 h# d" P]/ h5 _$ [1 Y4 D

" |" o- w% T4 ~& g$ Nturtles-own
; e, o- T" t3 T4 L6 G[
. R( }; X0 m# [/ w# g/ l$ k  S# }  speed     ;; the speed of the turtle8 n+ C% V0 Y" k1 f: q7 b& H, n
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right8 |" f% c' D- R) \9 G3 j) E
  wait-time ;; the amount of time since the last time a turtle has moved
* z/ j# {  K; z  ?$ j; u]
) S0 r  G# J. c2 A
5 _) _/ I: m4 N. {6 n# \0 T# Spatches-own
+ Q! Y0 m; ?6 i' L, l, w[3 \9 ?; o, c  C  C
  intersection?   ;; true if the patch is at the intersection of two roads, G* n2 L% W' N
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.8 i7 I, U$ d/ ]8 ^
                  ;; false for a non-intersection patches.
% X9 t) w$ Q1 M3 k  my-row          ;; the row of the intersection counting from the upper left corner of the
9 d0 p4 _& i, R; @$ D: ~                  ;; world.  -1 for non-intersection patches.
7 Y" |2 x3 {1 _  my-column       ;; the column of the intersection counting from the upper left corner of the
  Y$ b  G& m- j, D                  ;; world.  -1 for non-intersection patches." q/ w2 ]5 P0 N. u4 ?
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches., j: o4 P& \/ _' o& O0 b
  auto?           ;; whether or not this intersection will switch automatically.  K, o, D4 C: i0 J
                  ;; false for non-intersection patches.
) ]' B# O& [$ L]( Q( f) u& p( i$ d' D

* B4 n2 q0 \7 K4 l  w7 ^$ a3 y1 V: H# V' z( ?
;;;;;;;;;;;;;;;;;;;;;;
0 J. y/ `$ B: v$ f- p) b$ q6 f- D;; Setup Procedures ;;
; O* h! ^2 O, j5 S8 u. G% S6 E;;;;;;;;;;;;;;;;;;;;;;
2 {4 x; x  p- X( B+ B" [1 y- S: G/ I1 Q) @! R$ S5 Z* n- J
;; Initialize the display by giving the global and patch variables initial values.4 U: [" t+ G$ }+ X- V1 I; a
;; Create num-cars of turtles if there are enough road patches for one turtle to6 y3 Z8 x' _. u7 `, ^9 R% M
;; be created per road patch. Set up the plots.4 `6 U5 |4 @+ d; X8 g+ s9 q
to setup
! @4 ]3 ^- z* D& g/ E  ca
: S" T. S& N: U  setup-globals8 ?. h0 j: ?0 x( u* {+ d0 l1 {
# Z% V' ~* j" C" G/ S
  ;; First we ask the patches to draw themselves and set up a few variables3 m; x/ ~( \, J; d! W
  setup-patches
+ v5 R' \" q& M  make-current one-of intersections  v( w! t# A- E
  label-current  _8 P! o5 q, g4 V! X% I

. W3 x/ i+ Q+ l  set-default-shape turtles "car"
& p# |: W, o6 z3 G8 C: I, q$ n! O$ {4 D
" t* \7 U) V# y* L0 |* A. K7 a  if (num-cars > count roads)
2 ]3 H5 \" H' T; f9 h! T  [
6 N1 I6 R3 O# |) k: F    user-message (word "There are too many cars for the amount of "
+ _* }0 a' y1 Q1 A2 V                       "road.  Either increase the amount of roads "5 j5 p2 H' l" m; z. X6 r4 L9 O# V. J
                       "by increasing the GRID-SIZE-X or "
7 i- D0 m+ s  t. M: }1 c0 Q                       "GRID-SIZE-Y sliders, or decrease the "% i2 f. |& @, p& \, f
                       "number of cars by lowering the NUMBER slider.\n"
1 D, y, U& G/ m& X                       "The setup has stopped.")0 ?; G6 }- b1 x+ T( B; \
    stop
3 a5 T  Y* _; X" x0 R. J. r: @  ]& }: f+ m* T# h3 d/ B: C" @

( a$ R; V# ~$ O( J! z4 m8 }  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color' Z, N2 m" Z: I/ ]4 [6 ^
  crt num-cars; Z6 n+ z5 ~, X! g
  [4 q0 P6 M/ L, z. K% s- o
    setup-cars
- P7 B! [' }0 s    set-car-color
, l' ^/ A& I. q% h- i+ R    record-data4 f# y# `$ t8 }: e1 K# v
  ]
2 U+ p! E3 `& b
9 k4 U  t) @0 B0 ^  ;; give the turtles an initial speed
1 ?' [; J0 H8 z  ask turtles [ set-car-speed ]. E% o) D6 n; H! [# t& L* \+ }: V* _" y

; d5 r( {5 l6 l& S; I  reset-ticks
9 A" p2 B' u/ _; {4 X" V) Pend
  H7 C4 x  z) Q$ ?" ~) g! l
9 A% ]! |* B& P1 I* J; E, n4 V/ O;; Initialize the global variables to appropriate values
% F1 I0 r. V8 r3 h( `to setup-globals
5 ]  b/ i1 G* v4 z( }0 g2 s  set current-light nobody ;; just for now, since there are no lights yet* X, ]$ u% X, k+ w1 _
  set phase 02 D3 W0 i6 ?* W3 F7 g6 }
  set num-cars-stopped 04 w3 r# N- B* N
  set grid-x-inc world-width / grid-size-x
0 j5 f7 ^& b3 T* Q  set grid-y-inc world-height / grid-size-y. _' m/ G* a! U& L

+ R2 `6 S: J9 e7 L9 w5 N2 i  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary% y& |$ ]1 l% D' L
  set acceleration 0.099
( V4 Y5 r9 X: v" t. y- Rend
$ V1 M/ z( W8 o- @) }* a3 }' Z  c; T6 g& X. }% s
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
1 V) `: B/ Y/ j; Q;; and initialize the traffic lights to one setting
( ~9 m: R* f+ S. s- }+ ?" e. l- pto setup-patches$ X( }( `  O6 v  s& ^" @9 A
  ;; initialize the patch-owned variables and color the patches to a base-color! `7 n! M8 r  g9 [( Z9 P
  ask patches
, r3 C. \. U* L  [
1 B" E! x, U+ n4 \2 }; S1 P    set intersection? false
2 y* M  j) E; h, a    set auto? false
! K  S, k  X; [) s    set green-light-up? true
1 B' n4 {! S" L( q3 C! P! V; \7 X    set my-row -1( M( k/ f, s" Z) V. G% ^
    set my-column -1
! i+ q' h  P4 g3 ~- m' k    set my-phase -18 L8 G4 E9 c  x4 f/ k
    set pcolor brown + 3
- Z/ K' ^  T, J5 Y6 U  ]! i' M" v# t0 s0 B( j+ l
" ^0 Q! g  N1 o: S4 ^
  ;; initialize the global variables that hold patch agentsets
9 |7 D" @* j! O5 ]. U; I9 u7 J  set roads patches with. p9 E/ e! N! _* h: Z% Z% k, @
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- T4 {8 U0 G( H4 v$ V( Y8 L9 P
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], `/ Y7 Y4 v* z
  set intersections roads with
" T9 D; F$ e* c6 T+ _3 m+ W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and0 V5 Y# Z. C* e# J& Z, S
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( s! ?  K3 ~0 |" j

( i# S+ H. n- q  ask roads [ set pcolor white ]
8 P! N9 m/ i- Y" Z    setup-intersections
% B0 R- [0 J5 ^( |5 e* ^end6 P/ m+ h& V0 g2 ?! x! i
其中定义道路的句子,如下所示,是什么意思啊?# t% n9 o9 ^6 q$ H
set roads patches with
" _2 W9 Z6 `6 r    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 q& V0 W, q1 t' }5 F: C" I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' F' z  T% `# Q8 K" Q; H1 \
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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