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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。
& b9 w( a0 k* d8 n* V( v  Onetlogo自带的social science--traffic grid这一例子当中,  T* C2 s  e' w3 r1 L7 [8 `
globals
2 e7 C$ q  E& f6 U[
/ P. |4 T; y  ]/ h+ K  grid-x-inc               ;; the amount of patches in between two roads in the x direction8 i2 b1 L/ _/ t5 O3 ^
  grid-y-inc               ;; the amount of patches in between two roads in the y direction7 h* l, f% @9 s; N. Z  V6 M. y
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if' Q' C  f7 f% p# Q
                           ;; it is to accelerate or decelerate
7 b5 L+ F7 B: f4 d  phase                    ;; keeps track of the phase9 |4 N3 P& u) R0 Y5 f
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure+ z* i3 x# J( N- [6 c/ m; P
  current-light            ;; the currently selected light
6 ~  T: u( }2 M& h, @8 a7 @. F1 [& v* b, m
  ;; patch agentsets
/ D. Z# U' F4 [- X9 I0 q  intersections ;; agentset containing the patches that are intersections
4 s/ s8 _* F- |- L8 E5 v% h  roads         ;; agentset containing the patches that are roads
: [& q+ s9 b" T* G. i]: ]/ n4 |" i4 V7 V0 Q) [5 J
7 G8 M0 l; U: F6 S% w, E2 ?/ K9 `
turtles-own& s: [: l' J/ Y8 G1 W# |* E
[
# N2 ^6 c3 J9 `" E& t  speed     ;; the speed of the turtle7 t7 G5 ]% C, N- _( R; m/ N5 x
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
# |3 _9 j) G6 |: V) J  wait-time ;; the amount of time since the last time a turtle has moved, s8 {! }& \9 g0 A* Q% g) D" P
]- ~% u2 S* y1 u3 |$ H: Y

& g% M( j( l: |$ k) d4 o7 upatches-own+ K7 z+ b9 k- I. X* }7 b
[
9 ?7 N" g; P0 |  `" ^  \  intersection?   ;; true if the patch is at the intersection of two roads. a. u& X, L) w
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
! |# Q4 G4 X4 u                  ;; false for a non-intersection patches.1 k6 m; z+ A2 e- S# y" S
  my-row          ;; the row of the intersection counting from the upper left corner of the$ D4 M4 ^. Y, [  g- V4 o  O
                  ;; world.  -1 for non-intersection patches.
  {6 n6 t8 N% ~* Q$ y  my-column       ;; the column of the intersection counting from the upper left corner of the8 v9 v& ^2 i& k! J5 F* o: c
                  ;; world.  -1 for non-intersection patches.
+ A# Z% P3 @. s  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.4 ~9 O( i7 f. j% W' |7 h
  auto?           ;; whether or not this intersection will switch automatically.
1 j  J: \6 r$ p                  ;; false for non-intersection patches.
# N/ j: [9 x( j: `]9 j" C) N  E5 B1 ~' \

6 A/ h4 p1 F% d8 N) X" e9 {8 y
8 `* H% J& T7 f# C8 E3 g;;;;;;;;;;;;;;;;;;;;;;6 M$ p$ u9 |2 i1 E  p" k/ W
;; Setup Procedures ;;7 }, L: W* y( a5 I
;;;;;;;;;;;;;;;;;;;;;;
: @$ ~9 T3 p0 L, Z. T% q5 X
* z% Q/ H: T3 F; l/ Y7 {; D;; Initialize the display by giving the global and patch variables initial values.
, Q& \. x& J9 p6 x5 A5 U% ]6 N# ?;; Create num-cars of turtles if there are enough road patches for one turtle to/ f, l! G/ c# E- P
;; be created per road patch. Set up the plots.
1 H9 U* Z/ R3 K5 Mto setup
1 I( S5 s! Y9 A$ `' k5 B4 D, ?  ca9 j5 i9 V7 d* M9 U$ G0 S* w
  setup-globals6 z7 [8 S6 L# G) a3 {
/ {5 r9 G% ]' P
  ;; First we ask the patches to draw themselves and set up a few variables' R* g  p+ W  U6 Y+ y1 ^4 Q
  setup-patches0 {" F5 Z+ j. P. `5 i
  make-current one-of intersections
; P" j& y- E0 F0 a  label-current
' B* d. C2 B9 n; E; l) a$ D: N4 `! e6 [& E
  set-default-shape turtles "car"# N2 E' r$ p& h% C

, J! G# J" {9 S5 ^% e  if (num-cars > count roads)- Y+ ?4 y, I. U' V+ p0 M3 h) v
  [
" e! C4 [. W7 y' _) q    user-message (word "There are too many cars for the amount of "% g# }5 F. y( ]4 n) [
                       "road.  Either increase the amount of roads "
" V6 i9 O4 Z5 O. T                       "by increasing the GRID-SIZE-X or "
/ M& J# G3 B- _( f1 m! d4 ~0 O                       "GRID-SIZE-Y sliders, or decrease the "
# @+ F3 S1 C6 ?: _4 [                       "number of cars by lowering the NUMBER slider.\n"4 _) e$ h: j7 m4 O& i' m  h/ w
                       "The setup has stopped.")# N3 @% w8 h, Z3 F
    stop1 _4 Y" a* u. S
  ]
# g6 B+ G2 K- W% L- N8 L: |; F/ ]& i: X5 d* B/ ]
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
, ]' ?) |1 k: q/ U2 H8 y3 h  crt num-cars4 c( k- p5 a7 ^, B3 _& o
  [
7 X7 M' x& a6 u$ u, R  v    setup-cars3 A/ d; w) z5 W$ ?+ o
    set-car-color0 S: n! `! y- D0 j  F
    record-data5 v1 H' @$ g& m- ?+ O4 D  \
  ]
( T( @: C. s3 N( o( }+ I3 A" f7 j5 B; J. o3 t* F% e5 E; O
  ;; give the turtles an initial speed
: X+ i+ A  ^; n% `! h9 R6 @  ask turtles [ set-car-speed ]
2 S* g1 a3 z3 X" r! P9 M2 a
3 {/ Z1 }0 z# m" i: G5 n# V. G  k  reset-ticks0 |- Z3 t. o0 @& o0 V/ _7 D. n- Y" f
end0 u; W$ j' K$ u$ i
$ [2 N0 V! {9 x0 y2 Z# Q+ B/ o
;; Initialize the global variables to appropriate values* a/ [& w  c; n" Y% N
to setup-globals/ j8 Q) P+ U% ~
  set current-light nobody ;; just for now, since there are no lights yet
0 r! v4 l  N$ L9 p# ^4 I  set phase 0
/ s; a; ]8 |* t" ?; p- i. ~  set num-cars-stopped 0
1 T2 b+ {& Z5 g  d  set grid-x-inc world-width / grid-size-x
; O1 a0 w3 J6 ^% J& f9 J  set grid-y-inc world-height / grid-size-y
; m' }" {, u# a# A' }
$ I7 ]/ n( q1 o0 s' d, D+ B  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary2 a' t; o+ V2 ^6 S7 \
  set acceleration 0.0990 Q. P. U3 M8 m; [7 }: \0 j! G
end3 s: p& ~2 P7 w/ T0 ^" U7 d
+ c# {) s& J2 o- G
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,7 F2 v8 f* m" c7 m# q% J
;; and initialize the traffic lights to one setting
/ \1 p3 {, r6 r! fto setup-patches: b! B" a3 V7 b0 R2 E1 e- n* a
  ;; initialize the patch-owned variables and color the patches to a base-color+ y9 `  L$ L9 R: r% V5 J
  ask patches" r; [) f; M8 q2 L
  [5 h$ s" t2 I  P+ X! i. N
    set intersection? false4 ?2 c0 D+ S! r* G! ?) V8 _# i6 K
    set auto? false& v" T0 A: i4 u: O# y8 r% \( Z
    set green-light-up? true2 o2 f/ L9 m4 P8 N" y5 _! W+ J! |# g
    set my-row -1% Y5 K- N$ a5 t
    set my-column -1$ A4 U2 _7 [- V9 H( ^9 w4 l
    set my-phase -14 `  w" e2 k$ D. m8 j
    set pcolor brown + 3$ P+ b6 `+ L, h
  ]
# k9 K2 w$ t, b: w& e. v0 w8 A  p4 _. X) s6 c4 ^( \
  ;; initialize the global variables that hold patch agentsets; F5 y, z+ A! S
  set roads patches with
; s& M- ^" b& \) Z9 b- ~. {    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* A% `3 E; I+ {9 q# L# z/ k    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* J  ^5 m" R! U, ?  O. \
  set intersections roads with
" l% {2 m9 @% h+ l& L# y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and) g  x& e& t2 f/ ^. c
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; ^6 C: t/ m/ j" h) D/ q

1 N# s3 G7 F3 K2 x" i. [  ask roads [ set pcolor white ]
5 P1 U0 M8 G& a* n* f    setup-intersections0 _1 I: }5 d; h1 G5 Y
end6 x* C' n; m- v- O" V& \* X  d
其中定义道路的句子,如下所示,是什么意思啊?7 o+ H6 D' o% ^- l2 I# p, c8 j
set roads patches with" y; L$ r, i+ w/ }- `4 D: m0 i
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! G8 ~* w2 d1 G$ H- F1 T" Q7 }    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# w( \2 o4 d/ W) \& [8 f. N2 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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