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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。
4 C* ^$ P2 L0 Lnetlogo自带的social science--traffic grid这一例子当中,/ t2 l/ o( w5 n, V
globals; f; W/ |1 U3 v
[
( p% m, h$ L& i8 K) ^& l  grid-x-inc               ;; the amount of patches in between two roads in the x direction' T7 M$ m4 U8 }, A
  grid-y-inc               ;; the amount of patches in between two roads in the y direction9 W  o9 x2 m( r& L
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if  J% N) Z  ^; _. e2 ?5 d
                           ;; it is to accelerate or decelerate& ?  c" C1 k) ]  B- L8 [0 J; Q$ {1 P$ N
  phase                    ;; keeps track of the phase& ^' I: X  W. a  T1 l9 t0 n
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
7 r, c4 b* G1 Y  current-light            ;; the currently selected light9 U9 z$ [* y: q: G6 v. U' J9 G

: }1 `/ F) S% r4 v, N  ;; patch agentsets
! ^. L' X8 k  B1 i$ n  intersections ;; agentset containing the patches that are intersections
5 l3 V8 A8 N7 B  roads         ;; agentset containing the patches that are roads  p% s3 |9 Q/ @+ X6 l
]
: a3 q4 {/ q" R- p: {; i" D4 O
" a8 {4 G6 h' f0 {turtles-own
8 y% I' Z# y0 _: t3 d& k+ ~[1 c0 V) u$ M' r6 ]- b# M5 A" g
  speed     ;; the speed of the turtle
0 d/ J/ e6 B$ \( w- {8 ^  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
4 K: @5 ~6 A* F" S, \- k  wait-time ;; the amount of time since the last time a turtle has moved5 m* f3 U) I/ J% g" l1 X
]2 B! b: R) y- k2 r. q8 v6 l, ~5 m& [

. G  l2 G$ B: O1 [. k+ |, }patches-own
8 H' ]2 E: T0 i! B7 q' N[
" I# D: \+ Q9 W8 j" a  intersection?   ;; true if the patch is at the intersection of two roads* t7 g6 V' m+ U8 |- L! \/ q4 K9 K
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.0 F6 \: Z/ ^# S/ K% e- X. n9 J
                  ;; false for a non-intersection patches.
* b5 r9 T8 T: D+ Z  my-row          ;; the row of the intersection counting from the upper left corner of the6 V- M+ b- h3 h5 c$ b
                  ;; world.  -1 for non-intersection patches.8 D9 Q+ @3 ?, M3 \# T6 [" x
  my-column       ;; the column of the intersection counting from the upper left corner of the
) j2 \6 C! W; I; B) I                  ;; world.  -1 for non-intersection patches.! J% W  f$ b: X# e: B" S9 G
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
* b7 ]! `! u8 I  auto?           ;; whether or not this intersection will switch automatically.
5 ]  c' X: p/ g9 S6 E* u                  ;; false for non-intersection patches.# [( i: T+ e4 F8 W1 c) a8 W: g
]6 Y3 k7 z, n$ l/ l7 p) y5 z

) f" h" s" y* A2 X1 L* T1 Y# j
! A& ?) w$ o0 B8 T;;;;;;;;;;;;;;;;;;;;;;
6 Q( ~( }! j5 U: g8 };; Setup Procedures ;;. N: e6 t. E$ f7 b  b& t
;;;;;;;;;;;;;;;;;;;;;;
7 f/ B% Y/ ~. c5 Y8 b0 y, v! Y9 B
% O! _2 P8 i7 q' e# b/ O! e% D;; Initialize the display by giving the global and patch variables initial values.7 v- Q3 A: {9 p" i" J
;; Create num-cars of turtles if there are enough road patches for one turtle to0 d4 S$ |  r. g+ y
;; be created per road patch. Set up the plots.
4 [* X4 Q; I; e7 I& B& Nto setup
) G$ E& d- w& z  E3 K  ca
& v1 s( X% t% R% i# N4 W  setup-globals
, @9 p! z1 r1 b; P" f4 D6 }8 Q8 i4 q  z$ \
  ;; First we ask the patches to draw themselves and set up a few variables! F! S: N/ C# k! o) A; b
  setup-patches
4 a6 E. S8 a3 c% B  make-current one-of intersections$ z! [1 H3 m$ w5 F: }
  label-current; g" U' b$ R4 _  y
! q* U, [. m0 b( J
  set-default-shape turtles "car"
4 Y  e& n+ A* C) A- o# R! c; T6 |0 ?9 t3 |: V3 w) g
  if (num-cars > count roads)( e) ?) \& e. M& }: P8 @
  [
) E7 Y. }7 s$ f4 |& g    user-message (word "There are too many cars for the amount of "/ J& n3 N4 v0 K6 F
                       "road.  Either increase the amount of roads "
9 h% v9 g+ d' s) n2 H                       "by increasing the GRID-SIZE-X or "- [/ {# a# `% K6 M6 `2 Y
                       "GRID-SIZE-Y sliders, or decrease the ": M6 U$ t1 p1 P4 [% U# M
                       "number of cars by lowering the NUMBER slider.\n"
( C+ b6 l2 r0 k; L                       "The setup has stopped.")- l9 |8 n  G) R0 A( `9 K1 a9 D; D! _1 ?
    stop0 i1 Q- {5 t& F0 Z7 q# k4 W
  ]1 P. V' b2 b3 Z8 ?5 Q  C: [

- i5 w. S0 g9 ?! A$ A( K  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color: N' }" `  d" p
  crt num-cars
" \7 g, u; B5 P/ x. E: E; `  [
$ ?* k( `7 m, x. p0 }1 ]    setup-cars: ]7 t- n- ?0 @% T0 T0 e
    set-car-color+ F/ G$ |: @2 G+ w9 E; m4 K
    record-data
% Q1 h  z6 Y! Z4 w  c1 s1 v  ]; n6 Z8 d/ W, p! ]

) l5 `6 z6 p4 p7 @: }  {6 \/ q6 o  ;; give the turtles an initial speed
' B7 ]% i! F+ T  ask turtles [ set-car-speed ]# g; r* f$ A: p5 \, B6 `- F# X+ i3 T1 W5 K
3 f& ]5 G' B5 b* ^( Z& b8 J, h7 t
  reset-ticks
3 q8 S. q. `9 m( t" u' m: oend" r5 e) i' n" k  }: F) ?
) S# q3 }3 R7 N3 l% o- R. v; `+ ^
;; Initialize the global variables to appropriate values
. R( ~4 u, w: @) K/ q+ wto setup-globals
% X6 R7 t+ b2 p/ y7 n  set current-light nobody ;; just for now, since there are no lights yet
" i9 x9 Q- s; _1 B% x  set phase 0$ n, _$ W9 S% G- g0 @( a6 Y; m
  set num-cars-stopped 08 t1 i* r+ ]) i8 n
  set grid-x-inc world-width / grid-size-x
6 p* Z) F6 G! m- H! q: B) `% x  set grid-y-inc world-height / grid-size-y
- Y. w& _# l1 `) _& R
$ z) W% H; d" F; Z. Z. f0 k  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
# ?( D0 j& _# l# ^  set acceleration 0.099
1 `' s/ O% Z8 H! I- s+ Uend8 T! I3 Y# \- N) Q

+ N8 W9 T  C( q;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
' ]+ w4 M4 m- g;; and initialize the traffic lights to one setting
! z2 B8 f0 u1 L9 Vto setup-patches
/ E' N, j+ ^  e5 Q0 J  ;; initialize the patch-owned variables and color the patches to a base-color
4 S8 p  f, h  K! l  ask patches
! P; j! s5 l1 N7 x4 D" n( \2 E  [
" a& X) i* J' D1 r. ?    set intersection? false
/ C9 J! h0 n+ m" Y2 k7 w  t    set auto? false( J1 f6 A2 k5 y7 \9 C9 K+ W
    set green-light-up? true
1 H% p7 ]8 u( K  d" F/ S    set my-row -1
" j# W* \- z& Y! Q    set my-column -1
, q: O7 O. [5 T* Y2 n: W    set my-phase -1# N& g' M: O' y4 ?3 m$ K: |
    set pcolor brown + 3& H0 f" o$ K- o7 p* h/ D' A
  ]: [9 H" P' C& [/ e

* e, K1 z  |: b) i6 M  ;; initialize the global variables that hold patch agentsets. c7 o# L2 ^' V5 O
  set roads patches with
$ F; E6 n# |% T8 d    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 m, {5 ]8 |; o% D& o( W    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ T! I1 ]% [3 Y% ~" _
  set intersections roads with
$ i: _  q& C7 n4 a9 L    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
" _! s, p1 e) b/ ?    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* Z# M9 i5 V" o, i; Q- a0 M
: b) {! O! B+ w$ e  ask roads [ set pcolor white ], |$ y2 L1 H/ V; J, m* H7 g) G
    setup-intersections
; m4 Y9 O% h$ z" xend8 O1 \+ k9 W. ~3 [
其中定义道路的句子,如下所示,是什么意思啊?
" l  g6 ]( b$ ^/ \( } set roads patches with
/ b4 i3 l# b9 t    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) D; c- H: w3 ]2 K" r2 ~: N: }9 a
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 D! N: W/ l4 E) a9 y8 @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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