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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。' F$ }7 [) W; J' ]& q4 Y4 D( F
netlogo自带的social science--traffic grid这一例子当中,, x+ O" O9 K0 ~6 c! c# `4 G- ?
globals
( c9 J; F, }8 l5 j[
" }7 N, D4 d. A! o, M& ]  grid-x-inc               ;; the amount of patches in between two roads in the x direction) L2 i% I% P( K0 X* y* X
  grid-y-inc               ;; the amount of patches in between two roads in the y direction7 K  I! w* P  m* N2 E  W- f) o
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if" u: e) @# b% c) v2 G8 C# n
                           ;; it is to accelerate or decelerate* u# y5 Y8 D( I7 ~4 U1 H
  phase                    ;; keeps track of the phase# b2 H; I% r* j2 ], b# z* F) z
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
' I! F4 p: ?8 ]8 w3 @" b4 s  current-light            ;; the currently selected light
' G7 R: s) L7 j+ n0 P+ _" j
( P$ D; y2 y: c; r& X  ;; patch agentsets5 V- @; u% n0 B! b+ q1 f+ m/ ]  q
  intersections ;; agentset containing the patches that are intersections
- `2 k- ^4 e% x7 H( r6 T  roads         ;; agentset containing the patches that are roads
; L7 h8 p$ O4 y! R: s( N6 d9 f]6 y- c9 a6 E4 K$ d. @" w8 g2 o6 Y
0 j' ~: d3 x5 T- d
turtles-own4 J. j/ c, E4 w/ X7 X& i1 E
[- U- v, [4 E# ?, v# i
  speed     ;; the speed of the turtle
+ @$ L  Y' Y9 l  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
% f5 G9 o* m  r  wait-time ;; the amount of time since the last time a turtle has moved
; Q  d& y' k5 H]7 D3 k1 U+ K: N6 }: u

9 f3 @6 o  u8 n0 {$ zpatches-own
6 H. o* x& ^+ \[
( `: U& p% u5 I' }& s& i* ]5 |  intersection?   ;; true if the patch is at the intersection of two roads
; h4 n3 p+ X& U  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
+ B: O, S. I5 k# q9 n2 `                  ;; false for a non-intersection patches.
0 B& Q- Q3 _9 [  U  my-row          ;; the row of the intersection counting from the upper left corner of the
& P4 A) p6 q' b8 _2 x8 d                  ;; world.  -1 for non-intersection patches.0 A+ n' _2 t" N2 U9 Q* ]  U
  my-column       ;; the column of the intersection counting from the upper left corner of the3 \+ n, Q9 E; c$ v. Z8 w4 H
                  ;; world.  -1 for non-intersection patches.
0 ~$ O" {8 ?" p; D* b/ Z8 c  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
  X1 L8 Z1 ?. h' W! L  auto?           ;; whether or not this intersection will switch automatically.5 ?: Q+ \) E, ~" l2 V$ _
                  ;; false for non-intersection patches.) p/ A. b# V2 u" D* {% n
]
* t6 C4 W: f! F# A: k2 y0 }; K' W- p4 G! G' O

2 A, P7 b0 D$ @$ g% m& @8 u;;;;;;;;;;;;;;;;;;;;;;" Y  l* y+ G' v& B2 f
;; Setup Procedures ;;8 N) `: ]2 G3 ^+ W
;;;;;;;;;;;;;;;;;;;;;;9 i- S  K8 ]0 c

3 e. |& x  ^8 G  W;; Initialize the display by giving the global and patch variables initial values.6 J# b0 R9 j, I4 @, L+ |0 ?9 K1 {
;; Create num-cars of turtles if there are enough road patches for one turtle to% R* G2 a6 f) ]5 K+ Q! w
;; be created per road patch. Set up the plots.
1 U0 ?2 u4 i- ?to setup
" M0 }* c# R2 ^+ w  ca5 o& R3 s7 Y' L
  setup-globals2 a6 D/ `1 \$ o# R. h8 ^5 s

& v9 u, A4 L* f2 u% P: k8 t# g3 p  ;; First we ask the patches to draw themselves and set up a few variables2 K% B8 [+ B5 z* Q: T1 c6 X9 U8 a
  setup-patches9 c. G! J/ A% ]% z# Y/ B) O+ f+ N2 m) }  [
  make-current one-of intersections
0 D' s) i: i1 ~& [* L$ t" E* x  label-current
* }0 B# _4 O! M# B& w% x; I% |9 T' _. `8 V4 T6 [% s+ Q9 H, l3 i$ R
  set-default-shape turtles "car"' N4 S4 F1 x2 T- ~- `

0 d7 C* `! Z5 q/ k! d6 }' i  if (num-cars > count roads)1 j- U/ [% p1 e, u* I
  [
' \9 j4 y! D6 p8 F7 r    user-message (word "There are too many cars for the amount of "2 k8 F' j4 g) H8 s- s
                       "road.  Either increase the amount of roads "7 I4 C9 a( K3 T; \4 L' J" s
                       "by increasing the GRID-SIZE-X or "& _7 `5 m6 R7 Q8 y* i  m
                       "GRID-SIZE-Y sliders, or decrease the "
- N9 c6 v# B5 t2 I. q( K                       "number of cars by lowering the NUMBER slider.\n"  F6 }4 B3 z- z1 X% a6 A
                       "The setup has stopped.")
4 K0 p) L& N$ f  N/ h    stop- D  C5 L7 p1 V$ f$ E* ?
  ]
" X, _, C% W+ d9 j: ?/ G# }
& L8 c4 @5 z! e( N  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
) y0 w% D  T7 ]6 `, K& Q! k  crt num-cars- C$ d& d# \8 {: y3 Z! S  E0 Q9 h
  [% p6 H" k! r: w! u& M9 U
    setup-cars
5 r) h8 C/ M; k! B2 H    set-car-color6 D. d2 y3 u" s. U
    record-data+ ^( i# n0 `6 v4 R
  ]
) l0 o) [5 a$ ^9 O# G) g
& J$ i2 p+ Q* s0 R( F  ?  ;; give the turtles an initial speed
6 C0 j4 E! f  J$ \' s  ask turtles [ set-car-speed ]! e5 v# H* u2 G% ?: V
$ N  T* `9 C/ V8 C$ ?* j2 G
  reset-ticks
4 t: ]  O" j. C+ l9 [: I6 k/ i3 `3 ?end
/ ]+ C! F+ h$ Z5 ^- D0 A+ L! J7 j4 f9 r% Z& Z
;; Initialize the global variables to appropriate values
8 |# T& `7 ?, [5 S6 @to setup-globals! O6 X! N" w9 q9 k
  set current-light nobody ;; just for now, since there are no lights yet
  |( l3 ?) Y2 x1 q9 H) Q  set phase 0# D+ w+ u: W) N
  set num-cars-stopped 0" O0 t4 M4 p: ]& O  Y0 N
  set grid-x-inc world-width / grid-size-x
2 s' n8 W9 _$ Z8 ~! b( |6 B# @8 M  set grid-y-inc world-height / grid-size-y
4 J6 }9 L+ Z9 o, \! m$ ]
2 e/ N$ R8 J  z6 |0 P2 g  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
5 C* q- U7 o# [+ Q  set acceleration 0.099
5 M5 U, O# L8 g+ C) y# Rend
* P7 h  T* L. x% D* a8 ~9 u7 h' U9 M- O) l& J" {
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,' t- P8 A3 d3 N
;; and initialize the traffic lights to one setting& p: e5 f2 @* {8 t' o3 q3 |
to setup-patches! t5 P. L  V4 ^
  ;; initialize the patch-owned variables and color the patches to a base-color
% m" T4 g+ K1 _# Q2 m4 A) _  ask patches
6 B/ b3 F1 D) j- l5 U  [
, E0 ~2 {; w! a0 a, S+ U1 ~    set intersection? false3 Q, q' {2 E4 m& e1 o1 b
    set auto? false" B! u- A% z% t
    set green-light-up? true
7 k4 J+ r4 v9 _' `    set my-row -1; j- p8 t& G, D) P' V% E" V
    set my-column -1
$ A$ {$ G! n" L3 p/ S! k+ k) E1 k" G    set my-phase -14 e' S$ I2 x* o& x+ f
    set pcolor brown + 3, v: ^! X& Q9 k$ V2 G  ~0 p; R
  ]" R- R) p: {, K6 b0 I" X

' y" O) _/ a% V9 W7 g  ;; initialize the global variables that hold patch agentsets# F& W# Y8 j( l/ B! b
  set roads patches with8 b, ?& y) t3 B: ?
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, X7 w- m4 j. i2 S; a* G    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; A) X2 m9 g) X8 o  set intersections roads with2 d  [$ v0 ^# C" H7 u/ s( F! i
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and4 x/ Q) X# y+ l
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  j+ l  f/ ?0 V/ d; U. Z
7 v, {( S3 g$ \' f  ask roads [ set pcolor white ]
/ S8 a/ o8 f/ O. F7 A0 g    setup-intersections6 S; Y+ N  {4 R7 Y6 t' a
end
# s3 p% D4 j9 k% I其中定义道路的句子,如下所示,是什么意思啊?$ N" p/ g* ]3 G& v
set roads patches with/ [% j7 h( F% x4 C: t$ o
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) }5 j2 t8 E' c5 z) ~    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% Z9 B  Y2 O$ c* i5 Q8 W* c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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