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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。. W" y1 b7 v' B# l( I
netlogo自带的social science--traffic grid这一例子当中,
3 S$ [: t) |8 _globals1 Z4 u/ r- n: D8 T
[
/ y5 s, }, t0 H9 R2 U  grid-x-inc               ;; the amount of patches in between two roads in the x direction' K& T2 U7 U6 A0 @0 B. V9 k
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
2 F7 Z+ U! k1 z% K# Q) `' c  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
9 K' B. J$ @& }" v, o$ e                           ;; it is to accelerate or decelerate# M7 g% V, F) c) P) y' [: k
  phase                    ;; keeps track of the phase
, Z0 o& s* c4 N* e  B6 \8 R  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
2 v& K. r9 ~# X  f7 O; f4 l: ]# ?  current-light            ;; the currently selected light" K# R+ n3 I/ K/ h$ r# ^
: y6 f5 H( h9 D( v! Q% o
  ;; patch agentsets( i: P' \( Z. q  K* F3 r  f, f/ t  g
  intersections ;; agentset containing the patches that are intersections
# W4 M5 e7 O4 g- U9 q  roads         ;; agentset containing the patches that are roads
- O& f/ z& j4 U9 h( s( ?]) {3 d4 s  y9 [9 q
( n  d; l' H( i  V
turtles-own) S6 D0 l6 O+ U& Z2 X5 J% N: q
[
0 T: ]( \. u2 z* i" l% C4 z  speed     ;; the speed of the turtle
0 B4 i2 Z1 Z1 T: ~; \6 T  up-car?   ;; true if the turtle moves downwards and false if it moves to the right; U7 Q  b% r# B1 U2 `
  wait-time ;; the amount of time since the last time a turtle has moved! C: [# u7 Y1 B1 z4 I3 s
]
. B' c+ L8 x- }. z
3 q. C. `/ W/ _# Apatches-own- S: l# w. P3 i, a7 {* l0 H
[
; R5 v/ m/ S, c" D1 b  intersection?   ;; true if the patch is at the intersection of two roads
0 i( I2 ^( d- S* t1 P+ v- ~% o  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
6 C/ U1 Y4 U* p$ [* H* s6 l% [* E                  ;; false for a non-intersection patches.5 z7 u" v' O& [1 u2 S/ {3 c
  my-row          ;; the row of the intersection counting from the upper left corner of the
% M( c$ T6 }8 V& s6 z( v                  ;; world.  -1 for non-intersection patches.- t. x1 D/ N& w4 X- @
  my-column       ;; the column of the intersection counting from the upper left corner of the
0 P' W+ P2 D( }) K                  ;; world.  -1 for non-intersection patches.: @8 b! _, W! Y9 J5 a
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.# |: q" o8 b; c" D4 S) y# |  @
  auto?           ;; whether or not this intersection will switch automatically.
7 [% `; i# X9 C# N# {% ?  w6 _                  ;; false for non-intersection patches.& w; ^$ a; f# |: K, `3 q
]9 v' `  _  O3 i' o5 Z

) h% `" m7 s+ k7 D5 V
7 X( a" e: [! l/ v  s;;;;;;;;;;;;;;;;;;;;;;6 R& |0 |* N* l( I3 d& Z
;; Setup Procedures ;;8 {* @3 Y/ G5 V8 e
;;;;;;;;;;;;;;;;;;;;;;
- d$ G; Z  A  E
  Z+ O: |! p: h& u;; Initialize the display by giving the global and patch variables initial values.9 C- R* |/ |" O8 z* w
;; Create num-cars of turtles if there are enough road patches for one turtle to+ e3 L  j7 R( l
;; be created per road patch. Set up the plots.3 [1 S; F; ~! J/ g
to setup
6 a1 o  m0 j" o. D" }  ca6 c( @9 q! {+ s* D- e, }' A
  setup-globals% ~5 q* g9 @1 e2 s: I9 m

# V: B) |% r' Q1 D, j, {. l2 s  ;; First we ask the patches to draw themselves and set up a few variables
/ h" y* {* C& x  m  r" ]  setup-patches
  m8 w6 t) [7 a2 _  make-current one-of intersections/ S4 f9 u2 J% o4 f9 t6 X' \* S
  label-current
/ G8 |) ?: ]% ?5 J5 T
. Q- A0 t6 V6 }$ {  set-default-shape turtles "car"
, H& z! A% j9 s2 U$ k! s& O8 C$ J& B+ B* x. o' U* R
  if (num-cars > count roads)
+ X6 K6 J: v1 |; p  [* \5 t% K8 f, P
    user-message (word "There are too many cars for the amount of "9 ^, m9 v0 \0 \& |
                       "road.  Either increase the amount of roads "
- X. u2 \2 ~! M& J/ a                       "by increasing the GRID-SIZE-X or "2 P( k+ c3 R% A6 R; P
                       "GRID-SIZE-Y sliders, or decrease the "
; W8 s# V6 I2 |# |( g/ O+ L! K% Z                       "number of cars by lowering the NUMBER slider.\n"
; b, D+ N, E, C5 e. t: }; X                       "The setup has stopped."): [7 F6 N! U- A7 V2 Q4 @
    stop
: T0 V( p. |5 h7 ~3 w3 |: `  ], i2 t3 b, S( G' m; ]

, v2 P: L% q2 p, u/ G  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color3 }0 L# \" q' F( v% L5 W9 D4 I" F
  crt num-cars3 M$ a2 v# r2 V. ^0 @9 t
  [4 s( L1 {4 C' D' ]" c* e" ?
    setup-cars
9 L2 ]0 S! g5 s# ?! T6 ], g' Q    set-car-color. R' V# }( h& |5 a9 M5 v
    record-data
! t: p8 f; B  o. w- U; n. K  ], z( I; j( i! L+ d, j$ Y  F# ?

7 o* G, a8 C, \  ;; give the turtles an initial speed4 q3 ]) K  y4 L1 t  l0 E
  ask turtles [ set-car-speed ]
( _! ]9 w8 n; o5 C& I% Q0 z. Y! Y2 r% v( s0 ^: z
  reset-ticks+ I- _' [) I0 N. R2 i5 T! P& J
end
5 y) G+ l% I* [$ _& j; s* M9 e
;; Initialize the global variables to appropriate values8 x( y  k& x9 w( p
to setup-globals
0 S# x# y0 i& Y9 r, Z  set current-light nobody ;; just for now, since there are no lights yet: A9 T' s9 `/ x3 M2 k2 X
  set phase 0
3 f# e$ K+ {: G7 ?  set num-cars-stopped 0
+ y" z6 N+ w3 s  set grid-x-inc world-width / grid-size-x
1 J  d+ j; p0 Q8 U7 _# w% u  set grid-y-inc world-height / grid-size-y# i* |1 a2 o: ?; U! V
4 X# ]8 G! ~6 @, {  q  E0 Y
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
  Q' m$ b" N& `+ I$ s+ O  set acceleration 0.099
' g# b* ^# }6 F% Iend7 @8 t+ P* \+ x9 V2 q

6 [+ h; e  C% D3 E( ~0 G2 Z# W;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
+ U: r' M: `( W0 a2 q4 A;; and initialize the traffic lights to one setting7 X4 J" x- [3 u' p2 K' i
to setup-patches
( ~9 W$ J8 {- s& V1 J  ;; initialize the patch-owned variables and color the patches to a base-color
* R  ]/ _# _( k  ask patches
# Z/ K; j& s5 n  [
3 T  c5 u3 b& p6 E, [$ i: O8 `, q- V9 |2 A    set intersection? false  |  [! J' Y% V2 j5 H
    set auto? false
+ n' Z# b6 T, l1 b2 O) T& b    set green-light-up? true1 i* R; E' T; |2 [0 \
    set my-row -14 ^0 t5 Z" |& Q2 u5 K& p! A
    set my-column -1
& l$ c. k' b/ t' y7 S# |) e0 a" @    set my-phase -1" d' ^) ^, I! L! f5 f+ z+ ~6 T
    set pcolor brown + 3
+ h& Y! b/ T1 |- C3 C  ]
( h4 Q7 h& Y& F$ i. ]) K
& [4 b! e* ]+ T  ;; initialize the global variables that hold patch agentsets$ n6 W7 Y. W( J3 n
  set roads patches with( Y5 z1 m- F. G2 J4 q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or- x6 N$ X; Z) B& ~% y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! Y7 s3 t4 z4 w4 y
  set intersections roads with1 M3 L5 ?7 B, \: q0 _% @* I
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
% q" L. U+ S9 p* U    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 u6 R) e. r* ^+ ]
6 |1 t& M7 u, f: c: ^0 m
  ask roads [ set pcolor white ]
( p$ @  L+ ?8 [  B; Y6 X2 d    setup-intersections( r" n) v+ @9 @3 ~8 ?
end
/ g9 s0 p! D: {! y6 l其中定义道路的句子,如下所示,是什么意思啊?
3 [( }: ^) q3 i4 a' L) O set roads patches with
4 H8 C' \" @( l$ g3 b; d. `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or0 W6 d; E! u, K/ f
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ m- h3 ?# r, T) O7 h: m$ W  b% ?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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