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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。0 M# `- Z7 q' k9 _
netlogo自带的social science--traffic grid这一例子当中,# X( c0 M3 d# {; X" C
globals5 ?# J1 y, V; u/ |! V
[
4 t, |" T7 T% [. R+ e$ H7 }* V  grid-x-inc               ;; the amount of patches in between two roads in the x direction; T) b) b, r  }: I9 q! s
  grid-y-inc               ;; the amount of patches in between two roads in the y direction* Y- U- H* O/ [: u5 v( E
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if/ b' W. Q0 ^9 t; x' x
                           ;; it is to accelerate or decelerate
, [: p" l3 g3 E0 P  phase                    ;; keeps track of the phase
9 G' k# b: ^, r: H* t- A1 `- j  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure2 h$ X$ X' V% K
  current-light            ;; the currently selected light- G" M/ W- j+ @2 A5 F
  n  ~. i. v& T5 \  a
  ;; patch agentsets
& t* s- {5 U- @  p  intersections ;; agentset containing the patches that are intersections: b6 P" [$ ?. a" ?
  roads         ;; agentset containing the patches that are roads
3 e# u3 P) G5 A, y9 Z/ N% T$ ^]
& Y( D& v5 k) U8 z% X6 l# c( H; O! d& R; ^# k
turtles-own
7 ]/ M% e0 x, g* H[4 t4 k# o; i. ?/ ]3 o( Q  \
  speed     ;; the speed of the turtle
; {3 X% Z* [7 V: X9 K; l8 v- _4 u  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
, {4 G3 K9 f" l9 ]; `  wait-time ;; the amount of time since the last time a turtle has moved  p) ~% R6 M) G0 }! C
]7 v5 d# G, P& m" S3 }% `; q! |: {

/ l' Z) r1 O: h9 X/ Ppatches-own
6 G' t. Q6 h0 J+ C% f[
% I, l9 R& K# n/ _, H  intersection?   ;; true if the patch is at the intersection of two roads' U. [! N* q4 D
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
+ k+ r, F" G4 ^, P  W; e                  ;; false for a non-intersection patches.  w( X, F3 f. @2 I- V
  my-row          ;; the row of the intersection counting from the upper left corner of the
1 X& |7 D% w; f: F+ r                  ;; world.  -1 for non-intersection patches.
# s, m- L3 F, }% j- y' C  my-column       ;; the column of the intersection counting from the upper left corner of the
+ e% Z( s/ o' ~# h1 R3 d! ]+ Q' n                  ;; world.  -1 for non-intersection patches.; D: K3 s( V+ H  F. v1 U
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
2 t. Q0 t; V2 o5 [  auto?           ;; whether or not this intersection will switch automatically.
/ B' X8 T. k7 Z' Y9 I                  ;; false for non-intersection patches.
7 ?, M- u9 R3 L6 `7 y6 T2 Y  G]& O9 _9 {, M7 `5 i0 ^

2 M7 t/ w! B# C
# ]% E0 [' B# E" K% W;;;;;;;;;;;;;;;;;;;;;;2 `7 R* w( D% u) j  r7 `
;; Setup Procedures ;;, `3 d  Q9 P5 k& R! h, N
;;;;;;;;;;;;;;;;;;;;;;
! U! r! @" f; K( h) C. l
! b2 U6 W* P( w, r+ j: T;; Initialize the display by giving the global and patch variables initial values.
; D: c: {9 y6 W" z4 h& O;; Create num-cars of turtles if there are enough road patches for one turtle to$ \) |% |% d+ |) Y+ I8 M5 S
;; be created per road patch. Set up the plots.- j& l4 K* L9 Z5 K% e
to setup% W& Z3 x& ~+ l8 L- p9 r) A
  ca( }- i+ s* U! a& w7 W  J! ~& I
  setup-globals
  o8 A$ q* u; C7 r7 Z- ?# d
* K/ y( q7 Z+ i3 ]. o& m: C  ;; First we ask the patches to draw themselves and set up a few variables  L: m/ s- ~5 z6 j) A5 U
  setup-patches8 X3 N/ d2 H0 \' h* J
  make-current one-of intersections( [! f/ x) t% u! G
  label-current' X; C0 ]; W0 N* U( x! f1 A7 @

3 \1 c: _* A, M+ v8 _: {  set-default-shape turtles "car"
3 T  t- ~5 B1 `1 E9 b/ z9 l/ x3 I% F
  if (num-cars > count roads)( c9 e+ V, w4 i6 q" \4 V8 |
  [/ {1 H! x4 x2 p, L" Q0 H
    user-message (word "There are too many cars for the amount of "
( \/ D. ^/ k5 I* |4 a) f                       "road.  Either increase the amount of roads "+ ~# a) G: c# Q
                       "by increasing the GRID-SIZE-X or "
! v6 k& d) o( G3 ?                       "GRID-SIZE-Y sliders, or decrease the "/ R4 \* O0 n9 R. R( \( u
                       "number of cars by lowering the NUMBER slider.\n"
( e3 z( K" |( _" M3 j7 D- I                       "The setup has stopped.")
0 R' [$ s% p( p" _4 Q% d/ U; n    stop9 s1 N3 P* d8 i' J3 l0 h* ]7 A
  ]
; ~6 d! Q1 d+ w8 L) u5 P1 t7 n
  o3 O) b) V) e9 \  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color8 F, @! T* K6 n4 C: s
  crt num-cars
: P" a1 Q8 @& k3 y, R  [
0 R- A* D2 _6 Z    setup-cars- r) x) x+ T( `" {* [0 L: R: j) D
    set-car-color; h  A0 I7 I$ J- ], |
    record-data
5 R7 ]4 E3 r8 I1 J  ]1 S9 q- _5 Q" B3 }# N" t  S

9 r7 z8 {8 u) Z3 X  ;; give the turtles an initial speed/ Z1 m: M/ C8 N! v
  ask turtles [ set-car-speed ]( y6 }! ]! I" w- r! m8 O3 @( C

6 w' W  p3 u- t  reset-ticks6 f& s2 P8 D; D
end  [' _1 q" P8 z1 ~& p1 J
3 t: ^" [2 E+ O4 N$ o) n6 Y
;; Initialize the global variables to appropriate values
+ |1 K" Q7 L7 A6 B1 N, R8 w. ^to setup-globals4 s# ?# y: r0 C2 p% D
  set current-light nobody ;; just for now, since there are no lights yet9 |4 e2 M/ `/ s
  set phase 0
3 r0 ~4 E2 }6 Q* T, x" c  set num-cars-stopped 0) |6 }2 l  e* V7 j
  set grid-x-inc world-width / grid-size-x
" I' Y# g# p& e% [2 W1 ]) Z  set grid-y-inc world-height / grid-size-y
% p0 a7 [( Z5 e5 V( ~2 d2 d* U
6 ~+ j; a7 w  E4 w4 h- U# y  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary! o& H  V% M4 z/ `# Z( K1 N
  set acceleration 0.099
% h. d* p, P/ {# f; ?" G8 d# j& Iend' m- C& X; L' P9 q9 `
6 U5 a' n: z5 H2 t& m4 h- L4 E
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
( Z0 t$ @' D6 x  W6 A3 k! R% @;; and initialize the traffic lights to one setting: a4 K  d$ m' u) i# q
to setup-patches7 ?- F: F, n: b
  ;; initialize the patch-owned variables and color the patches to a base-color
& [( b/ W! ?0 U; w9 \  ask patches' V+ t& y) a7 M: V/ _
  [
- L- J, N! R3 {; `% |    set intersection? false# }4 v. J' P6 X" B7 C6 q7 N* i* ^
    set auto? false
: ?# c2 ~' _( Q# H& d& u0 [& k2 c    set green-light-up? true
& V. o8 f! w' A, f- s, d0 s" E' s    set my-row -1
/ V$ q$ W3 s- k9 l' z. t6 i; u, m    set my-column -1& E( B* q6 W! ]% u) f
    set my-phase -12 E/ \7 K* `5 d2 i$ _
    set pcolor brown + 3+ q+ {) w) ~( u% F! Z
  ]7 e$ n1 h* y0 m+ G' B; p# G

5 `! ~5 ?+ I' O. {7 u  ;; initialize the global variables that hold patch agentsets
: e1 j+ X) c. G- ~; i+ M  set roads patches with' [8 o) ]" J4 B7 J; c
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' L' E: O: j  x/ I: B  b, |1 L
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ O( ~& _8 c: }4 Z- a# X% t
  set intersections roads with
* Z0 R. _" u" F) R0 e3 I0 a    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and0 m( O9 v7 j& g/ D% t! E
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 A6 Q4 l# I+ L" T: U# q8 y: r  z3 O" T: _' `  @9 v
  ask roads [ set pcolor white ]3 A( E: G4 i- `0 @+ r: s; y
    setup-intersections- S  x% R# v, q7 @
end
2 A1 X8 K- n7 c1 I2 h% Q其中定义道路的句子,如下所示,是什么意思啊?0 K! [0 q  Y2 I2 W
set roads patches with& K: `# l+ }0 J* z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! Q+ q* U$ g) r/ \$ O& N    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 U+ J# Y) Q6 k/ M( U9 x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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