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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。  M5 U5 J" [& m6 q) g/ b; ^5 S' [
netlogo自带的social science--traffic grid这一例子当中,
$ R+ H) T/ [1 L' W3 }globals
- W6 {& p" ~1 u/ j8 V& |[! t# O" }& Z) j6 t5 v
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
* Q$ _" g+ y7 b- O4 ^  grid-y-inc               ;; the amount of patches in between two roads in the y direction+ x% W' T% r* ^# t: U4 q
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
; F+ I. F4 u" W$ v! b                           ;; it is to accelerate or decelerate
5 o5 u# X/ N& k  phase                    ;; keeps track of the phase9 A5 R5 z! ?9 N+ k% N
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure1 Y  H% \5 h& j
  current-light            ;; the currently selected light
  ~: D0 S# ?) r2 M0 U" R# G9 ?
. T6 |% b: i; R  ;; patch agentsets
1 ^; H- d5 p4 v1 n* `  intersections ;; agentset containing the patches that are intersections8 c1 K6 @# }  z1 P3 Y
  roads         ;; agentset containing the patches that are roads8 w1 ~: j8 |% @0 M' |& }
]
  {2 Y6 O  j/ Z. E- B2 |) `# q+ }- @) D7 Q( S* V
turtles-own
8 s$ K* J7 ~4 f0 |: i[
- u  m# `5 g9 o; y  speed     ;; the speed of the turtle
/ R6 p7 X' u9 v. H  up-car?   ;; true if the turtle moves downwards and false if it moves to the right& t4 a, F+ C. o6 R2 k
  wait-time ;; the amount of time since the last time a turtle has moved
4 C$ o$ h% g6 A6 x]
& Q/ ^( C, F! ~: V  e) `
# M0 P, C$ X+ N$ _patches-own, O+ Q' d3 D+ h$ j3 M0 `
[1 f% u; I5 |1 F. z; n
  intersection?   ;; true if the patch is at the intersection of two roads, \0 u8 K' e) _3 h0 l, N
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
9 Z' Q+ K6 B- }# l- \                  ;; false for a non-intersection patches.
7 H9 G; _; d3 J, l  my-row          ;; the row of the intersection counting from the upper left corner of the
8 ^6 F& D% U, v2 D1 L0 y                  ;; world.  -1 for non-intersection patches.
+ E2 R$ z9 V7 R2 g8 g; ]  my-column       ;; the column of the intersection counting from the upper left corner of the' d% \. n, ?9 a$ e8 Q" `. k
                  ;; world.  -1 for non-intersection patches.
" t. K/ P. z3 w- y  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
$ Z: M! Q: L2 a  auto?           ;; whether or not this intersection will switch automatically.
* Z7 L; \' c) y% n  K  d                  ;; false for non-intersection patches.
3 Q+ L2 W# _4 H# E" o6 v% [" l]
9 x  K. }( b! k8 \: S( D3 Z. P0 h  H$ N' q3 Y

. L. r4 c: z2 c( N, i$ P. ]. r;;;;;;;;;;;;;;;;;;;;;;
/ \1 E+ {8 X: Z3 `3 C, Y) z% E;; Setup Procedures ;;
' o6 q7 o2 h' J, q& p( Z+ Y;;;;;;;;;;;;;;;;;;;;;;
( }0 N+ H9 v3 L
+ M0 }7 ?/ ~2 j+ m;; Initialize the display by giving the global and patch variables initial values./ _0 ?/ l" L  O) z
;; Create num-cars of turtles if there are enough road patches for one turtle to% g. D0 `) Z1 Y9 Z2 {) k3 g
;; be created per road patch. Set up the plots.) p$ b/ M7 z1 v( J4 O
to setup% D2 C3 B8 x9 Z8 b
  ca" C/ o# k$ R' d1 ^) N- T
  setup-globals
& @! u  \1 S3 x
! P/ g6 H( L, T. \: I  ;; First we ask the patches to draw themselves and set up a few variables% \+ T* v, G0 M8 t6 `+ s0 R/ ]
  setup-patches
( e- X2 B  K1 W  J! Z: o; K  make-current one-of intersections' Z) D% r7 W- p* D- y
  label-current
3 b; c7 O( E0 y( |' j. v- u2 ^, B' A$ }
5 J9 `, Q* U9 ^1 E7 z9 t  set-default-shape turtles "car"! o0 C+ h( f, \' t( g/ I+ k

) f6 @) h; b& q+ j" n4 P5 a  if (num-cars > count roads)
$ b, j' V! _4 q  ]" J, `  [
3 Y; x. i% d0 N+ Z: S& t    user-message (word "There are too many cars for the amount of "
9 u; C- o" P$ m# J' w$ u! d                       "road.  Either increase the amount of roads "! N8 Y9 D4 x; {, v6 S' r; ~+ w
                       "by increasing the GRID-SIZE-X or "
2 |6 o$ e. h& m& A                       "GRID-SIZE-Y sliders, or decrease the "& e4 D# W" A+ i. ^7 D& F* b) e
                       "number of cars by lowering the NUMBER slider.\n"
. o+ ^0 }  e0 p* w7 |8 I; W6 V8 L                       "The setup has stopped.")1 d6 `( d+ C1 m+ e; p
    stop$ g- J/ x1 @$ s1 }* @; q; v
  ]  m/ O+ J4 k! g, L$ s

7 @& S6 A1 ?" ]  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color* a) \# Y% T& e/ U
  crt num-cars  P2 [9 A- B* Q9 `5 n3 ~" Y
  [+ t7 G4 b: a% T& t6 c( }' N5 n
    setup-cars4 G, U8 M  D1 n* n0 a/ E4 d' X
    set-car-color
) `; s+ s2 e) k    record-data
" O/ o0 e; o0 I/ J! `' K; L: _  K  ]  \) J. i( j; `/ o
& {0 l; \4 M  e% p
  ;; give the turtles an initial speed
1 P  k4 K! G, l# t; H( t  ask turtles [ set-car-speed ]. @" J' B) e+ P6 \+ B' d' J* n% |
# F4 N% W0 }' D" u
  reset-ticks
8 p4 y! X: ?& N" j% m  jend
* X/ H) _+ E0 B4 @* q9 h9 Y" _0 B; K$ c+ n
;; Initialize the global variables to appropriate values+ a2 X3 Y/ w- ^/ }6 Z9 W& E
to setup-globals
6 X% `0 u3 Q$ O( Z- [  set current-light nobody ;; just for now, since there are no lights yet
  B6 X3 ^: p+ i  set phase 0
4 Z7 v* P! u' I+ b  set num-cars-stopped 0* e! y5 X+ ?% Q9 ~  G
  set grid-x-inc world-width / grid-size-x
2 X' a) o( w3 T1 x4 X; g9 x2 V* _8 G  set grid-y-inc world-height / grid-size-y
* ~% G% N0 r' F5 ]7 L" f2 ~  a0 L& b0 ]  y5 M* F- _
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary  P  b' o+ }- n* l& u- x
  set acceleration 0.099
. H# y8 ?6 U& e5 x& j9 J# Y2 j4 Zend
+ W6 y) \' \1 ]; z" j/ n$ Q
5 J- r, o  M) [6 s" ];; Make the patches have appropriate colors, set up the roads and intersections agentsets,* T+ b) z4 G/ }6 k6 D
;; and initialize the traffic lights to one setting
3 o7 [/ p$ j5 p7 h0 bto setup-patches1 E1 Q/ _9 ~' h! e/ K
  ;; initialize the patch-owned variables and color the patches to a base-color
) c/ t0 X8 f: O4 J  ask patches
. ^; f+ J7 D( e) K; I; A3 {' r+ S# _8 L6 E  [
1 C* D$ n$ j7 V0 ~5 W( Z    set intersection? false
3 `8 _7 U& `, b9 @: G/ z3 Y    set auto? false
0 O4 a& Y2 p$ C3 S3 F, r    set green-light-up? true
. ?" ^) t2 a' h) o; T6 T. o6 P$ G    set my-row -1
! r/ n3 H# }9 p- d0 _    set my-column -1
, ~9 o$ q3 o8 h+ K) l    set my-phase -1
5 }9 e& b( W8 Y9 i    set pcolor brown + 3
+ N1 y" V3 p  R) S: s- z  ]& W2 q% Q+ A+ h+ }% v6 t( @

4 L+ U$ X  X+ C  {1 D; k$ K+ n  ;; initialize the global variables that hold patch agentsets8 m3 @) X1 @3 ^7 E6 @! C
  set roads patches with
# |1 f8 V5 j/ J  a    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
2 B. r+ `) Y4 k7 [    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% N# y4 c/ F8 w
  set intersections roads with
9 F4 R. q  s0 u4 ?3 s4 U- {! a) o    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
1 u  {4 u; b- @) Z4 Q, V: \    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 W9 @; x: |2 }3 T, k; J( u( C
5 o& S+ u3 e1 b" E, {( ]0 `! j  ask roads [ set pcolor white ]
6 U( h0 w6 O  E, A    setup-intersections
9 [2 _/ ?" m" G$ Rend
2 `3 F& ]: |4 P- g5 i/ s$ {0 M( ?其中定义道路的句子,如下所示,是什么意思啊?; w7 O+ X4 n) b" L7 q9 }+ K) y
set roads patches with
. L% I% y) m9 F1 c& a0 ~! s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
' Q# |) v4 o" j+ j+ G# S( ~    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& F9 ]. z1 M) u: i9 u
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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