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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。& p+ z( W5 X  M1 p: ~6 `
netlogo自带的social science--traffic grid这一例子当中,
! P2 x& h6 |2 ]3 I( M3 M% lglobals/ G' J+ h1 ]* ~+ y1 a
[5 J4 f0 q, D# J) T% L
  grid-x-inc               ;; the amount of patches in between two roads in the x direction  v" p3 _" x' ^
  grid-y-inc               ;; the amount of patches in between two roads in the y direction5 }! ~7 K3 F) v) q* v
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if# n; Q7 K, j2 u  q
                           ;; it is to accelerate or decelerate
$ K8 I! E: K& `" G  phase                    ;; keeps track of the phase+ l+ u4 j( l( u) d  M( g& w
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure/ Q2 c5 `2 U: t* N3 I  H
  current-light            ;; the currently selected light
! p- J# m) w) u" K5 J9 {  }& y- _5 `
  ;; patch agentsets
+ f) s5 s" O! {, l- K/ r  intersections ;; agentset containing the patches that are intersections
0 m* V7 T6 D5 @& G4 G  roads         ;; agentset containing the patches that are roads- @' B# q. N, Q8 _0 N
]! J6 e/ t7 J! J# ^/ t

' P$ o& F! K+ {turtles-own4 t1 e' c- T1 p4 o3 \
[$ |, ~5 H- X7 N3 u$ `) L
  speed     ;; the speed of the turtle( Z9 q, t: c% A% J! B1 x5 @0 R( ]1 F+ w
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
0 b! W2 Z% }1 Y$ V. ~& M: q4 d  wait-time ;; the amount of time since the last time a turtle has moved8 ]1 a# [7 Q6 g& ~
]5 P0 P# R# W& c! u3 @. W3 z
8 E  t9 h$ {* b4 w2 E! h, C; B
patches-own
7 K4 j5 m3 l# F+ r2 F  C' A[, K. ]' {) ?$ q1 o) z3 f" u) }; R
  intersection?   ;; true if the patch is at the intersection of two roads: \( J/ p0 I7 M( ~! z
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
. J) \) P9 h  U1 e8 `                  ;; false for a non-intersection patches.- b; j3 _7 {) k2 K$ B$ b+ K
  my-row          ;; the row of the intersection counting from the upper left corner of the  {! P) F* }+ u" R! w9 }- N
                  ;; world.  -1 for non-intersection patches.
% m8 \/ }4 q- ]4 ^( H  my-column       ;; the column of the intersection counting from the upper left corner of the7 _0 D3 S. G& P5 t' i* |
                  ;; world.  -1 for non-intersection patches.
1 v! S! d8 Z8 k+ g* U/ V  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
; S7 I6 s, H" C, V" o  auto?           ;; whether or not this intersection will switch automatically.
3 ?6 |0 F4 g. b. ]8 P% _& f$ L( C                  ;; false for non-intersection patches.( v5 M& @$ U: p2 e7 N0 {
]
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, V5 k1 X6 X3 r. {% C0 P  z; l. q* b: H0 V- U2 W
;;;;;;;;;;;;;;;;;;;;;;
. s8 B: P; ]3 Q" @5 S;; Setup Procedures ;;
, w% A* j: R# P' c  t/ N# i$ H;;;;;;;;;;;;;;;;;;;;;;
6 X2 V6 X6 P6 `* s8 k1 `
0 Z$ k3 }" S3 _" V8 e" l;; Initialize the display by giving the global and patch variables initial values." c5 @( i* G; p, x
;; Create num-cars of turtles if there are enough road patches for one turtle to+ C3 f9 k8 ]# E7 ^4 ]! F
;; be created per road patch. Set up the plots.. F# U% Q* {( q
to setup1 y" F1 Y  y$ @. l/ O
  ca$ Q7 S- r7 p0 T
  setup-globals( b8 T$ ~1 w$ Y$ s7 ]6 [

3 e. u) D4 N9 @. ]  ;; First we ask the patches to draw themselves and set up a few variables) ]+ r3 W+ c! H8 `! P! r$ x
  setup-patches+ p0 o. X( X1 W$ `
  make-current one-of intersections
  Y- \" b: q# p* ^  F0 L# s  label-current
" v8 B+ D" D1 _( |$ U5 S% E, D
) ~7 n2 u& h! E. y5 Y2 n0 b8 T  set-default-shape turtles "car"
: {3 w& ]$ B' P4 V
: ?0 i: h. n; Q& ^8 d  if (num-cars > count roads)) u5 z$ S' ^6 |+ }+ Q
  [
; J! ^  [5 |9 q. R. ~0 y    user-message (word "There are too many cars for the amount of "
% p. B7 v$ i( \                       "road.  Either increase the amount of roads "$ b8 Q/ A. q5 S* F* ^7 P
                       "by increasing the GRID-SIZE-X or "1 [( w7 q: \/ \8 K
                       "GRID-SIZE-Y sliders, or decrease the "/ f, k. e$ z* ~0 R2 N5 A
                       "number of cars by lowering the NUMBER slider.\n"
" x. F) h: [! Q5 S1 J# S                       "The setup has stopped.")
6 v2 `" w7 p: t5 b+ _; d2 N    stop
& ]3 G! c5 Q0 ^$ ^. Q% T  ]. K4 R7 Z+ V  z7 f9 l1 e4 \

9 X0 Q0 s$ Y8 g0 T- O9 I4 _! y  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
. G" H, l  D  e! k& v  crt num-cars
" ?' [" D7 O- q/ H& k# q# p& z  E: B  [
2 O! J! M. S: c, ~( L' t0 T    setup-cars  O4 O% W7 _0 ?. A: W& K
    set-car-color# C6 w/ O- T( E0 s( }' X
    record-data8 T2 p( ^. Q' J& ?5 I" p1 z
  ]% C" j/ ~4 Z: o

4 t! H6 U" q0 n# v2 x' A% ^  H/ I  ;; give the turtles an initial speed
: b; r5 G; j" q9 r: [, o  ask turtles [ set-car-speed ]9 U2 P+ u: G, n
. H; J7 C- Z5 S, L
  reset-ticks
( U( a5 z+ A+ K" W% C0 X( gend
/ y$ K1 }% c2 r! J( Q
8 \% q, {' ^1 X! O# {;; Initialize the global variables to appropriate values
, I/ T; ]  |' E' T! \+ [to setup-globals% k/ X3 O' D& a
  set current-light nobody ;; just for now, since there are no lights yet
% |% i* P4 {; ~. F  set phase 0
4 w/ Z2 R! f2 U7 b: N  set num-cars-stopped 09 M6 D6 }9 |* M: v5 A
  set grid-x-inc world-width / grid-size-x
0 m- {/ {3 }" w' c( ]. k: {  set grid-y-inc world-height / grid-size-y
! V8 @4 Z; l0 j9 v' N! ^- y  w) p/ q5 X0 ~+ U* r# O
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary7 H3 D9 k8 z( f& Y5 Q8 e
  set acceleration 0.099: e* l$ Z7 \* [7 |+ R$ ]# y
end
5 u+ I* |3 ?3 Q0 N7 a( X/ X4 A" ~( Z$ R0 ^; f% b# q7 v5 l* B$ j  _
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,8 W- n& `- ]0 E, j
;; and initialize the traffic lights to one setting
# ?# `6 |8 ]) K, l, w* Uto setup-patches) t0 a6 @3 n% h8 B: o
  ;; initialize the patch-owned variables and color the patches to a base-color
/ g# d1 Z' \' x6 F! A9 N- v; `  ask patches
& s% I. B7 H. H$ H  [
+ X! T. q4 \3 V    set intersection? false
% H4 q' T. J: j9 X* ^  f    set auto? false
5 Y0 K4 _  _  }  X7 R    set green-light-up? true
1 Y7 Z  F% V2 g1 P& {' \+ z    set my-row -1; v! D1 M' [+ Z0 P- N4 f' {' F
    set my-column -14 R) `- c) n: C* g. _: u; J9 o
    set my-phase -1" U7 l3 c/ p8 S
    set pcolor brown + 3
4 G0 ]9 }1 K" A4 k- z2 c  ]( X' @- R) X2 \9 H/ r- y
: ^5 ^; L9 G7 W% F9 x! V3 w
  ;; initialize the global variables that hold patch agentsets6 F4 v$ g, T, H! i  c% N" f" Q! c
  set roads patches with! q/ C% S! i! i. f* T3 u
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ I, M+ c8 ~* x    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* u% U; n- X. t% F* a  set intersections roads with5 G. M" c0 {+ a9 L
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
  Q" v& ]$ K7 x0 F    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' `& x. D8 C# x" p. O1 e! ?! G2 T
) U; V+ _) ~7 m% Q% H
  ask roads [ set pcolor white ]' N& E) N$ g& l& v8 _7 }
    setup-intersections. k- R9 x$ W1 ]" A
end  X; C& Q/ z0 H
其中定义道路的句子,如下所示,是什么意思啊?
; \0 s# k* Y$ F( h6 `1 w4 K) w set roads patches with. F7 B, N7 i1 Q: M, x" A
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" D: S# a9 X' r' {) q3 ~
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% v8 |  v' M9 j8 V0 c* ?$ 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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