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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。2 ]4 }# ^, f2 E6 c4 \: `: H
netlogo自带的social science--traffic grid这一例子当中,; p* l! h' o! r' s- Y9 b! K. K
globals
7 f  i/ ~) Q- ?/ o8 q1 Z[/ Z% X; _, ^1 _& [9 O! a
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
, X7 R+ ~5 s, d- Q5 o$ M  grid-y-inc               ;; the amount of patches in between two roads in the y direction$ B( X! f+ q  H' I
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if/ m: B' W& }% q. l8 W
                           ;; it is to accelerate or decelerate+ v" M) P6 S) s% G6 a
  phase                    ;; keeps track of the phase0 F0 }) {' ?% y0 M
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
9 G! M: ?5 z+ l) c  current-light            ;; the currently selected light
& h" Y3 ^. E* g5 o+ V
6 D6 |; r& m5 j6 S) m* G, z  ;; patch agentsets1 A" q) |' l  E' y- H
  intersections ;; agentset containing the patches that are intersections9 C) n6 m( q2 H9 {
  roads         ;; agentset containing the patches that are roads8 \% P/ a* `  q2 a; H
]5 y3 Z. z7 R9 T$ Y
- u" ^' j3 T, |+ O
turtles-own( d  E( z% W, q9 ^
[8 |/ Q- ^# B; O3 G8 p: ~& Q6 L5 x5 k
  speed     ;; the speed of the turtle$ K( r3 h; F; a; d6 i) X4 r0 U
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
0 J" [% r$ N9 x( h4 v: K$ Y* u  wait-time ;; the amount of time since the last time a turtle has moved
- r) \" B) w/ ~( ^" v; O]  ^% n, W6 d: x* i. A; i
* Q* D& e/ d4 E
patches-own: K. _+ A. C* ^$ V
[: c6 E4 v# D8 n: F( w( ~
  intersection?   ;; true if the patch is at the intersection of two roads
: X8 n8 h/ X; \& P2 @/ m7 P  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
; f) Y3 l6 k+ P" ^, ]                  ;; false for a non-intersection patches.
8 z( w; l& {7 S! u3 w  my-row          ;; the row of the intersection counting from the upper left corner of the/ o8 E8 g! E+ M. F: z' b
                  ;; world.  -1 for non-intersection patches.2 t+ ]! y, i* \! H- D& c
  my-column       ;; the column of the intersection counting from the upper left corner of the
& J* \- x2 s5 n& Z, ~  o                  ;; world.  -1 for non-intersection patches.7 x5 i0 M  v2 q
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
: C6 Z. s( H' G4 C! X; d  auto?           ;; whether or not this intersection will switch automatically.
, I, {6 z$ _/ K1 d7 i                  ;; false for non-intersection patches./ s. J$ f& v' O3 ]& @* g
]4 I2 S3 \; B! U( }6 l7 {

$ T9 d; b  Q4 v5 o+ t
/ u9 Y% A8 Z% S# f;;;;;;;;;;;;;;;;;;;;;;
9 \  F) c& x7 f" y6 k;; Setup Procedures ;;
! m7 R$ o% |7 O8 S# ~$ @7 ?;;;;;;;;;;;;;;;;;;;;;;7 [( o! f  G# B0 d
, Q: |( G. }0 j" G
;; Initialize the display by giving the global and patch variables initial values.
$ L, o3 y' f. K;; Create num-cars of turtles if there are enough road patches for one turtle to
1 A! u7 f# u9 {  t" `;; be created per road patch. Set up the plots.+ V6 Q! t! b9 H9 j
to setup
- h5 k  R9 L& V0 U1 x9 Z" [- ~+ p; b$ }  ca
4 V3 n  \" b: R; q9 A  setup-globals5 N$ O) c: h9 Y8 J

* H4 ^9 f* m$ g6 a/ J2 _1 H1 o  ;; First we ask the patches to draw themselves and set up a few variables" F) h; d" j3 Z) F" F1 A9 h
  setup-patches
5 W) K. q- R! L9 W% m; H  make-current one-of intersections6 e: g, j* W, N3 _
  label-current- g$ a9 ?! `: S% _% W/ `

; Q# J+ p! c4 l& g! H. \2 X2 g7 X  set-default-shape turtles "car") s# p2 u+ T/ w

8 |5 ^% d, ^7 ]& `  if (num-cars > count roads)
7 O2 N. `: k/ }  [8 ?( N9 F& ^( q/ }# z
    user-message (word "There are too many cars for the amount of ": ^8 L) ], g: P) a6 m& {8 e
                       "road.  Either increase the amount of roads "
0 {; l. k: g) d5 t, k8 A                       "by increasing the GRID-SIZE-X or "9 t  S( u( g( {- E
                       "GRID-SIZE-Y sliders, or decrease the "
/ ]: O! ^8 S+ y5 b                       "number of cars by lowering the NUMBER slider.\n"
4 [6 z/ d6 x% N2 e+ o                       "The setup has stopped.")
# ^5 ?4 o5 P8 m* {* L4 ^, n) f    stop
7 X, B+ ?9 v- Q# ]3 O+ n$ H: m  ]9 `, @8 f6 D3 Z8 f

4 K5 U: [% O0 f3 F: {% V8 R0 w  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
3 {, p9 l# G5 w  crt num-cars
; f% x' m5 U) X: b  [
3 r( y4 C; k) y8 p& u/ J    setup-cars
3 N7 X: s& o, s* o0 {: ^    set-car-color
) ]0 O3 U% S+ C8 E& p+ Y! K    record-data- d+ n2 i' [* C  o% o
  ]
- I5 P2 X1 z3 k
: j' _! s6 _. `+ t8 e; f% j9 \( ^  ;; give the turtles an initial speed3 R3 w" {" X  {+ ?
  ask turtles [ set-car-speed ]8 x* ~3 |& x: O8 t- C) @8 E
, P4 a" |4 j/ |( o
  reset-ticks
- r: P& ~, I% F8 m* }- ?6 f* q1 Zend# i) r' E: Z, b; p0 U' x

- b9 w( P4 c6 J- b( W;; Initialize the global variables to appropriate values
. N, W/ P! x) Hto setup-globals
1 B' l( T7 ^  Q  R. R, H6 H  set current-light nobody ;; just for now, since there are no lights yet: L" e% `' {. r' p  k
  set phase 05 t; Q" u8 g( r/ z7 W& T
  set num-cars-stopped 0
+ F$ d. q% v0 N3 z5 S) Q  set grid-x-inc world-width / grid-size-x
, ?; `) M7 Z2 A: n6 s' z; y( e8 r  set grid-y-inc world-height / grid-size-y% D" M* h* z  L& h7 {; N
  m, T5 g/ r5 J/ w
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary+ X' ?# l3 m3 Q6 [5 A; s/ a! r
  set acceleration 0.099' j7 _6 P2 a5 ]4 e: l8 W
end( V3 R* J! V8 Q) b

2 U; k* N( U7 w$ T& s2 C' k;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
( W3 T- V$ Q1 J9 c. U;; and initialize the traffic lights to one setting7 r& ?% S3 F% j2 w2 D- }
to setup-patches( H& O7 N$ K/ L3 r8 R
  ;; initialize the patch-owned variables and color the patches to a base-color; g; z0 w7 c( X/ c
  ask patches
) M1 m( G5 i; ~% b  [, v- D# c) O7 L+ D3 ?% J
    set intersection? false  Y" n, M# I! I
    set auto? false! w4 v8 g8 K2 ^3 T+ a" |1 P
    set green-light-up? true
# T7 l! c) c* M; s( i  Q    set my-row -1
. Z9 y, M9 X$ q6 Y! T- t    set my-column -1
0 Y& Y# c$ t3 _( j" V    set my-phase -1
/ I2 `+ A5 y5 o    set pcolor brown + 3
! o7 f: T7 t+ P  ]
3 [! o7 U* \* t/ V
' N2 c/ t  w" \8 b; J* r9 {  ;; initialize the global variables that hold patch agentsets" n' r5 V; p% l* m/ c) H0 K  o
  set roads patches with$ P: G' I6 ^. l) s
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) `* N, h# @( {: w' t    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ u8 O4 c" Y9 s( y6 g& }! A
  set intersections roads with' N* l- K$ ]) n( t
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
2 U6 S. i; j+ p6 h9 Y; V0 D% |# B% s' Q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 T8 }& I8 c  f  C: O2 J/ V/ _9 i+ R# X8 d9 G' J0 W. L
  ask roads [ set pcolor white ]
7 k& f2 v: c  O1 N4 R1 e" c    setup-intersections
! j% T: i. S8 N; D6 Q& S& [. ~5 a0 {6 Uend
1 u1 [, @' |- L, c# c7 Z  S& i2 y7 a其中定义道路的句子,如下所示,是什么意思啊?
; s7 g: j# b. N5 K set roads patches with2 W6 _# z! y, h# J/ J2 w
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or7 q) E; \- l9 x6 a+ F0 o; V2 z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( M8 }1 C% q1 ]* z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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