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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。
! H" \' v5 P! v: `5 d. ]netlogo自带的social science--traffic grid这一例子当中,8 D% U/ u) |# p
globals
  x4 O: ^6 U" g" Z* U[5 M, j1 I0 ]! @% t6 I1 t5 P  y
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
4 I4 U- Z, U# R5 p* [8 Y4 \  grid-y-inc               ;; the amount of patches in between two roads in the y direction
$ K5 W" }9 ^# j6 v1 t/ z, b  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
7 x; d- Z- {! l( x                           ;; it is to accelerate or decelerate
9 k  B" s& j& c  `' k  phase                    ;; keeps track of the phase
" z8 h3 x9 M' m# J' A! {  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure8 w1 A: n: c* x& M3 `
  current-light            ;; the currently selected light
9 N1 M6 K6 a: d
7 D4 M+ q8 L6 ^6 x4 @0 x5 `  ;; patch agentsets- d3 G; o! t3 j% m' @: Q
  intersections ;; agentset containing the patches that are intersections5 K0 [1 P/ w2 k% X! e
  roads         ;; agentset containing the patches that are roads
  u9 I* u. z, x% h5 M* s]
1 n( I) ?: V0 _, u4 i: [) A6 G; g2 W5 S( p+ g
turtles-own
& w1 S; L* }& h4 M- O0 W# u[5 I& i, Y8 A/ A) w- \
  speed     ;; the speed of the turtle% W5 ?9 \% W) R& w- o
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
* Q( K6 Z9 r) x  wait-time ;; the amount of time since the last time a turtle has moved' [6 _/ Q. V1 m- R/ I$ l
]
, D; R1 ^" z' R0 \1 \7 Q# \: p: Z) K0 P4 T" H- x& J
patches-own3 Q3 \+ O& y& \: e9 w
[
8 {4 s7 b% {, W  intersection?   ;; true if the patch is at the intersection of two roads% d4 n) g5 L0 L2 @5 G6 n
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.. w1 y# p; i+ O1 `" Y
                  ;; false for a non-intersection patches.: B+ z: Z" Y3 q2 l. ^; Y5 c
  my-row          ;; the row of the intersection counting from the upper left corner of the7 j* U  B% j/ J+ e$ M/ {7 E
                  ;; world.  -1 for non-intersection patches.
) c8 a" ]6 G3 I. w; a  my-column       ;; the column of the intersection counting from the upper left corner of the
. E* S  a, A+ Q: Z: b. S                  ;; world.  -1 for non-intersection patches.; e* {* H, L" @5 Z
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
& n+ @  t" Y1 w7 e  auto?           ;; whether or not this intersection will switch automatically.
3 r' H1 ^" c: ?+ n                  ;; false for non-intersection patches.: f" s7 O: t/ h7 \$ @6 K4 Y" |
]) D: o& e  w* m& ?, Z
9 k) G9 _1 F0 C( |
1 a( F7 ]- T: |  U
;;;;;;;;;;;;;;;;;;;;;;
3 p! ?" p8 L0 ?;; Setup Procedures ;;5 m' d1 G% c4 [7 F, e+ P
;;;;;;;;;;;;;;;;;;;;;;6 b) M2 X+ I8 e0 o% f$ N

* L* i7 ]2 C% p5 g, ^. G/ ]+ q;; Initialize the display by giving the global and patch variables initial values.; I5 _* d& J/ y- m; B* c
;; Create num-cars of turtles if there are enough road patches for one turtle to
! S! ^5 R+ o. ?% U) G! |$ U;; be created per road patch. Set up the plots.
# U! f1 A8 B  a- e/ a) oto setup' g6 D# V7 t3 @5 J
  ca) ]( q3 ~; S' F4 w
  setup-globals
4 S6 P! A# c4 _$ u( n/ ~& u
4 A5 @. L# n, H* @: G! z  ;; First we ask the patches to draw themselves and set up a few variables
: S! j8 U3 W9 b  N; D/ r1 W0 w  setup-patches
* I" w0 G# U, Y  make-current one-of intersections5 Z3 X9 t3 C/ p
  label-current% q' y& f+ |0 ~4 i

* ]& g1 ?, q6 I4 }3 ~  set-default-shape turtles "car"
$ K( O" @8 u3 m# D2 O1 Q% g$ M* e: ^  C7 X6 F" K
  if (num-cars > count roads)$ N$ N: M0 K, o. `+ ^" h# [) |
  [5 H5 G1 G, Y$ J
    user-message (word "There are too many cars for the amount of "
" g" O, `# Z/ g7 ~; \. v                       "road.  Either increase the amount of roads "
0 h: K  M* S. a7 X$ j' G                       "by increasing the GRID-SIZE-X or "
  H6 T8 o- [/ c" o                       "GRID-SIZE-Y sliders, or decrease the "* b5 t" ]9 ~/ Q
                       "number of cars by lowering the NUMBER slider.\n"7 B5 }9 ]2 i" P+ n' C$ t- q5 y
                       "The setup has stopped.")- q- `! q3 Q6 S" S2 i* J7 p( y
    stop
. u3 x- E& v. Y$ }$ P" l+ _  ]
* |2 N* S, g1 g; }% n* O3 g
  [) f7 ], T6 y* _3 q1 K% I  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
( e4 I  H1 k5 `" r2 R4 r& s) m  crt num-cars
; S7 P+ X9 {) E) m5 i, {  [
: a1 V3 u, W# ]. ]    setup-cars
9 M5 U% z6 t! w" ?    set-car-color! m1 J, w7 |: n8 x! U/ K: ?6 @
    record-data
% R" Z0 N0 L1 k9 D# i& ?' S  ]% L% |0 t4 B( S
. _, s6 M6 s/ \6 J  R! }1 {  [
  ;; give the turtles an initial speed2 p5 D( U4 ?( _* d! r, D
  ask turtles [ set-car-speed ]
% W. [6 q3 |4 y2 e. l! L/ a
# {% e0 ]3 C! ?! v' L. @  reset-ticks4 t- V6 s# ^6 W  {2 Q# g
end
% c4 q) _. {( w+ a5 e
$ N: Y% `8 U" ^, t2 I4 i9 @;; Initialize the global variables to appropriate values, `7 G- W$ e& ?3 B: P4 @& R
to setup-globals9 P) C& D, v1 F: d2 i" r
  set current-light nobody ;; just for now, since there are no lights yet
: ~2 A$ O" P* |  set phase 0
3 K( r8 x4 Z* R( r' w+ s$ g  set num-cars-stopped 0* f7 g6 Y3 A1 ^
  set grid-x-inc world-width / grid-size-x
0 f* B% G% f' ~  set grid-y-inc world-height / grid-size-y5 I0 e* d6 A5 Q
2 W' F. c7 A/ F3 ]6 m; L- w
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
' n/ i: ~5 i& m, F% M  j3 @  set acceleration 0.099. p' V! V4 t/ u* Q* k- O
end
( [. o* R, n% d- {7 M9 q
5 i. J4 @7 ?. f3 A6 p9 R;; Make the patches have appropriate colors, set up the roads and intersections agentsets,, |' @) L' D5 \$ S$ U# _7 P1 A
;; and initialize the traffic lights to one setting
  T$ _5 @% ^) m  l! ^to setup-patches
. `# Q# h: c/ p; x  ;; initialize the patch-owned variables and color the patches to a base-color/ s; m9 H5 Y2 J5 S
  ask patches
& g) b7 h: n& [3 [! u- P, r  [
3 v& s2 w7 r) B# _$ F" M1 V7 _* ~, _    set intersection? false: G, p2 Y1 J, q- Q4 \& r
    set auto? false- v3 N4 h. ~, m9 m
    set green-light-up? true
+ A' \' f! R/ i' [; ~  |3 D) h) ^    set my-row -1
0 f; Z, ]: p' I# ]! \    set my-column -1
- U6 i9 n8 l8 _8 V8 Z    set my-phase -13 {" ?) E) q/ u( g7 ?9 Q
    set pcolor brown + 3
$ [7 E& w+ B1 F8 v9 H  ]
# y& w' p$ n+ K( K( q; m$ q) \( Q+ ?0 \' ~
  ;; initialize the global variables that hold patch agentsets
; ?5 n6 R4 e, P; O  set roads patches with/ l% L: R4 |# @% C' H6 u. o% `
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 A& Y" Y3 k( p! I5 y/ D) _
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- k- h9 ?1 n# Q! f  C/ Z
  set intersections roads with# R8 E4 H6 q3 m6 e; l# U% K) l, Z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and" R: H% h2 u  V; w' l
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- @; ?. x; ~7 G( }. P% h% [$ h
. t$ X4 q& j% F  }5 w
  ask roads [ set pcolor white ]
9 h$ l# s6 q7 Q    setup-intersections! M5 `& a' }) r. z5 z* A9 O% ^
end7 N2 c" J: H" y4 |( V1 Z# F
其中定义道路的句子,如下所示,是什么意思啊?; n1 W5 X9 U/ B. k9 ?
set roads patches with+ a. D* K0 g4 Z8 p( H9 K# N
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) B. w9 n, `: g    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' A" ^4 j+ H2 I: ~
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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