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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。. A" C2 y% A1 X& g& M& m
netlogo自带的social science--traffic grid这一例子当中,9 ~4 o% X( ^, \1 f% T0 L
globals4 @0 g* n. k: G9 @% `7 ^& I/ v
[
1 ]8 l/ K4 y3 h7 P  grid-x-inc               ;; the amount of patches in between two roads in the x direction
4 C) C- q0 G- _/ e1 E4 Q  grid-y-inc               ;; the amount of patches in between two roads in the y direction
: `: T0 z1 ~$ B  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
5 u# g9 D+ g  L  `( _0 ]' m                           ;; it is to accelerate or decelerate
( I# Y2 e7 C7 X( B- L" P  phase                    ;; keeps track of the phase
& p# p8 S! p) _1 B8 Y  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure" i  ~$ A7 r$ T2 m: m5 t
  current-light            ;; the currently selected light! F: R9 J+ H4 }3 H
8 z/ `1 D* Z8 `* v+ F
  ;; patch agentsets; m0 A( C. \/ B4 @$ n
  intersections ;; agentset containing the patches that are intersections
+ E1 `. F4 A9 u  roads         ;; agentset containing the patches that are roads+ a( I. {6 R1 }* E9 c
]" h1 f! l! ~' z$ Y

& j* g- R, q# {1 C- X+ yturtles-own5 H$ j/ t9 j. Y( c
[9 L; @/ _$ C/ h: I1 O
  speed     ;; the speed of the turtle8 t3 Z2 {6 E$ X3 M
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right7 ^, U8 k& R& o% I
  wait-time ;; the amount of time since the last time a turtle has moved7 C" [2 S/ P8 R
]; A  Z- V! w9 B6 M5 `
2 _  |: z# V* `- `
patches-own
4 u+ f$ ]$ U. Y) j1 _[1 [6 p2 F& I0 ^) r
  intersection?   ;; true if the patch is at the intersection of two roads
" {' A" j# a) y" }4 w% M  green-light-up? ;; true if the green light is above the intersection.  otherwise, false., J- d' m" b' G0 E. [- T" d1 J
                  ;; false for a non-intersection patches.8 b. s0 ^2 }" d5 _8 ~
  my-row          ;; the row of the intersection counting from the upper left corner of the
; G4 {  u9 H+ F1 e2 @                  ;; world.  -1 for non-intersection patches.6 q  Z6 Q: ^0 D# [) G
  my-column       ;; the column of the intersection counting from the upper left corner of the: a5 e) X5 \7 d3 Y: J  |0 g- l2 T7 V
                  ;; world.  -1 for non-intersection patches.+ g) K/ L; B( `& ^; V4 ?3 f3 o6 t
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
; [& M- n+ Z$ O( _6 ^! ~  auto?           ;; whether or not this intersection will switch automatically.
' D( i# s0 j9 _* p5 A- A4 M- R0 j                  ;; false for non-intersection patches.
% B. w- j. e2 X/ y4 D8 Q) `3 Z]
% E. t# v2 X7 u! u: k* ^& f! x+ d9 J3 i
" ^. K9 G8 D9 |5 W
;;;;;;;;;;;;;;;;;;;;;;" k4 t: G, W- {- P0 p/ n& Z7 g( R
;; Setup Procedures ;;, c  j  T& o0 Y5 e7 V' @
;;;;;;;;;;;;;;;;;;;;;;7 i+ s7 ], `7 r( u6 T5 v# n' i

6 M3 S- `0 z. V( q* ?- L;; Initialize the display by giving the global and patch variables initial values." s! A/ [2 m; U$ P4 p9 {
;; Create num-cars of turtles if there are enough road patches for one turtle to+ D$ l5 q  `! N' f7 X1 u
;; be created per road patch. Set up the plots.
/ E: w3 Z& u: P& |to setup
0 E, ?. x% ]6 L+ {) q- k% f  ca
' ]0 B: c. ^5 ?* p$ i2 C( C  setup-globals
3 L$ d* w5 S/ h2 c
& d& D2 N7 b- }  ;; First we ask the patches to draw themselves and set up a few variables2 x# ]6 V2 n) b6 `4 D5 z2 j
  setup-patches
# ]! g+ I& B9 v2 c4 c2 N- z  make-current one-of intersections
% J4 y1 T5 X0 T; S& l# _0 x- V  label-current9 b8 o+ M2 w' ]; D

: P/ Q$ O, ~7 o% y$ d  set-default-shape turtles "car"
+ D% D5 [) {3 ~3 M, u6 ~$ Z
# U8 A& Y0 b& E6 u5 o  if (num-cars > count roads)
! z, v, {+ S9 F4 ^2 k1 X7 Q/ \  [1 Z" E) v1 P  X5 s4 U
    user-message (word "There are too many cars for the amount of "
: F% h2 ^, K, `                       "road.  Either increase the amount of roads "
' s: k: ~) x1 v8 y! ~4 N6 a                       "by increasing the GRID-SIZE-X or "; M- h& X1 U" R, q0 S
                       "GRID-SIZE-Y sliders, or decrease the "
! v( a/ A4 L/ q7 A                       "number of cars by lowering the NUMBER slider.\n"
+ Y2 G1 R" J) Q$ w; R/ p                       "The setup has stopped.")
( i3 n  Y+ l1 N; Z) I7 K# s+ a  y    stop. p( h/ W3 M7 M2 k- G: L
  ]
5 `, {2 A) g0 n# S8 b* ?1 g9 w# o
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
# O' }0 b9 f+ b8 @  crt num-cars
2 B1 c0 m5 s6 D0 @8 f( ^. x  [
8 O% v2 Q) f4 M  k. q* N    setup-cars$ m; ]8 I/ V8 O. W6 H
    set-car-color
9 `& f4 g- M/ D    record-data' m, d: h8 g6 T; P. m, k8 J
  ]* C3 S8 N+ }1 {( D. L* b& j/ b& V
8 B9 f; x3 d8 t# D" D# p
  ;; give the turtles an initial speed
1 d! v/ S8 _  h  [+ F2 i" l  ask turtles [ set-car-speed ]9 d$ k/ `# q, q# i$ v  n' m- a
2 h  _) ?) C3 ]- g6 u$ E: V: N
  reset-ticks
% M# C( q+ @0 O+ a; g' r" r/ M' `, Wend& l' s: k) L! R+ S7 V

' j/ N. g9 w& \) f;; Initialize the global variables to appropriate values: {# S" X9 h' R9 f
to setup-globals
; @; A+ N9 ~  D" Q/ {! ~. X, r/ y  set current-light nobody ;; just for now, since there are no lights yet
. G/ h) f4 k) K5 H3 r- n  set phase 0
! L& i9 d+ V9 A  set num-cars-stopped 0) U: g9 ~/ X8 a* M, w# [
  set grid-x-inc world-width / grid-size-x
4 K2 Z" V$ e$ B8 Z  R  set grid-y-inc world-height / grid-size-y
/ b8 ~! H8 P- A: Z  ?- c: Y/ x" L, ~3 z$ A! x
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
3 f2 t' c+ o+ J, q. V  set acceleration 0.099
( A/ C/ o  G' _8 K7 Y. p* |7 }end4 c( \* P1 @2 Q# t

, [2 o* O" t/ U) b) o;; Make the patches have appropriate colors, set up the roads and intersections agentsets,; c6 A! }4 {2 ]  S6 c
;; and initialize the traffic lights to one setting
3 I9 {0 g0 o7 Z( j0 xto setup-patches# C! R# F( ]  A
  ;; initialize the patch-owned variables and color the patches to a base-color" g$ Q# k- }+ A! s5 G: o5 E
  ask patches
2 a+ t' T0 F  v& m' ]  [
9 v1 u8 Z0 C9 W5 t* I    set intersection? false
  |0 [  Y* |: y8 i" o' F    set auto? false
' t1 W" H& M5 l. l: C/ e& C    set green-light-up? true
) g" \* T$ [+ z/ ^    set my-row -1
6 `6 O) B" j1 t    set my-column -1) v! R# W1 a3 c; Q% L% `2 H
    set my-phase -1% W, R& z$ A- P* ^3 X9 U, [
    set pcolor brown + 3) `' o; m3 i; {% _2 h. R+ q
  ]) s4 F; p" S. G2 r, l2 p

2 V& `" e) U( t# r9 C/ m  ;; initialize the global variables that hold patch agentsets2 B! D- p* F% A; ]* S- H* A6 H
  set roads patches with
- ^" T6 x9 ~2 t( A    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
. \& E$ B4 Y* n- {) a9 [    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 R) \/ e2 e  Q# x
  set intersections roads with: n: T$ [5 l5 t8 g7 B1 A* ?/ o
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
, ^" x5 _% m) M* r) K6 @: ?    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: X$ {0 l0 |" f5 f# Z9 z$ \, }0 |
  ask roads [ set pcolor white ]
1 b' i% j+ ]' b/ K    setup-intersections
4 U3 d0 h( W& ?$ U7 K$ r+ Aend- }1 q% V6 Z/ l9 J3 i: k- }
其中定义道路的句子,如下所示,是什么意思啊?8 @% L4 H- E# N/ A3 {
set roads patches with9 x6 F0 h: {0 t% W; ^
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, f7 I+ }0 E8 ^7 e3 o    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  c* l) f$ f$ ~) w% M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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