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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。% k3 D6 K' [$ K( Z" _5 j" X' s
netlogo自带的social science--traffic grid这一例子当中,
8 b, V6 p$ ^' T$ d, M  }, Rglobals
' |# G' p6 w8 x2 F9 \[1 e& `. c6 [2 Z* B$ M* v! K
  grid-x-inc               ;; the amount of patches in between two roads in the x direction; \7 G" W- V1 Y* a  ~4 ]) c
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
  \  x2 i! [! z" `6 n8 ?  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
/ U* h) x* U- f: L                           ;; it is to accelerate or decelerate
/ m1 B& A+ L; S; k2 I  phase                    ;; keeps track of the phase* Z2 }5 u! t1 m8 B# ?
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
$ ]  i2 q  w, N, ]  current-light            ;; the currently selected light3 P) X3 P- U6 @$ b0 A6 C6 E# t

3 C7 ]; R% b# f: X! M) X* Y  ;; patch agentsets
9 e8 l) F) \* Z2 ]0 l  intersections ;; agentset containing the patches that are intersections( a% I7 f: C  t: b* W
  roads         ;; agentset containing the patches that are roads; _/ `* a# @/ d
]
" g6 Z& @/ m% j: |+ ~6 L6 H5 L/ `7 y$ u# H# T8 m/ V& E, Q) d. \  V
turtles-own5 s1 v& a8 z6 X% C
[
$ r( e$ j0 F3 d+ Z/ @  speed     ;; the speed of the turtle8 W0 ]7 ~: q2 e0 W7 K' V
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
( y/ A! z; U3 Z  wait-time ;; the amount of time since the last time a turtle has moved2 g) p8 {1 [. d( z" W* L
]. V! g& t  z6 V9 q" x5 c/ \
: e! Y7 {$ c) s; g( g
patches-own
: j6 ]7 h) e/ M6 O* w$ K[8 l0 F! h" I0 U, |) |0 k, H
  intersection?   ;; true if the patch is at the intersection of two roads8 x3 {. z- u' q* f
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
3 |& v; a1 x7 n! e                  ;; false for a non-intersection patches.% I% D3 J( i3 U- |' ?
  my-row          ;; the row of the intersection counting from the upper left corner of the, ]" n# u) x$ n! ?* E7 `
                  ;; world.  -1 for non-intersection patches.
+ h7 U4 @; d2 T7 C3 H! @5 I  my-column       ;; the column of the intersection counting from the upper left corner of the
! H- C0 W( ]& Z$ D! g' O+ p                  ;; world.  -1 for non-intersection patches.6 W3 G# N. Q% K' L/ E* [$ ^9 N
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.7 g  J6 }1 ^0 v
  auto?           ;; whether or not this intersection will switch automatically.
2 t+ V/ [1 s- G+ p                  ;; false for non-intersection patches.
: E" h/ y( t4 [3 @% ?]
3 O; `- ~: {, s+ B8 Q
; Z% X2 x* O! p1 o; F- W  Q4 j8 Y: s2 I% y1 B( r! p6 F' t* E
;;;;;;;;;;;;;;;;;;;;;;
$ W8 _# ^( o1 o- ^6 ]( [) P' D;; Setup Procedures ;;
7 d' X1 N/ [: g' Y( a/ n;;;;;;;;;;;;;;;;;;;;;;
" {( F* K# }4 _/ u: y$ _8 K. W; t4 F7 X' t
;; Initialize the display by giving the global and patch variables initial values.
1 Q& o  |1 B# d3 p+ U;; Create num-cars of turtles if there are enough road patches for one turtle to
& p8 Y$ b% z. W" b, s4 j5 Z;; be created per road patch. Set up the plots.6 q  {' F5 D3 u! ^# A) l, m
to setup* a3 e0 J4 \, l
  ca
$ L, F5 W$ }. m  setup-globals* U/ O$ F7 a9 B$ a

# r* {( G9 S# d( t& |$ j% s1 ]3 T  ;; First we ask the patches to draw themselves and set up a few variables
' c, }3 k! L6 p; ]8 v6 u0 F% j" c  setup-patches% d! m1 r3 `9 F2 n/ [+ o0 c1 Y
  make-current one-of intersections
! t4 T1 `6 W6 U( F8 b  s6 |  label-current
& l0 L8 s& |# s- N0 z3 l& u$ T/ |9 `/ }- ^
  set-default-shape turtles "car"
5 H3 D; \( R& c9 B( X$ u  n' L
8 K$ @: }- J; o  if (num-cars > count roads)1 c/ K/ {3 }" H" }/ C4 [6 |  N- C
  [
, F0 }  n; ]" ^* s    user-message (word "There are too many cars for the amount of "( Z7 @# R2 W7 m- x. V
                       "road.  Either increase the amount of roads "/ U0 Z/ v" |$ A1 f7 j& ?; l5 l' c( n
                       "by increasing the GRID-SIZE-X or "
% t. u8 B3 [/ e! ]$ o- ^                       "GRID-SIZE-Y sliders, or decrease the "
8 ]$ Y9 g+ P, ^& o                       "number of cars by lowering the NUMBER slider.\n"5 }6 N# f3 H! \; \
                       "The setup has stopped.")
" u' A( l' d! Q    stop
+ ^" \6 x1 V& Y1 D2 x* R  ]
! m8 _3 a. j4 K
: V. L3 F" \/ W" u  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color: s( M* h8 e' ]3 w
  crt num-cars! T3 b- V0 l' `
  [& r- {2 P: E. }6 c
    setup-cars; M4 {8 [9 {( h) l& B  h  {( {
    set-car-color
! X. F& S/ `5 c9 Z0 l2 d    record-data% \: p0 V$ }7 }7 r+ \3 ]
  ]' A2 c, j1 U! |4 d5 ~6 f$ \' e$ m
4 |: V4 E, k) u2 V2 ~# k6 o) ~
  ;; give the turtles an initial speed
5 s' e# @9 N; E& I* a- k2 E* C$ v  ask turtles [ set-car-speed ]" O3 [# z" X- c# p( E

" D( v) C, g+ H. f9 l( J  reset-ticks9 W2 p) l$ A3 |+ e0 }
end
8 R! J" h5 M* v6 u8 Z: q+ T- y. r, Q# `
;; Initialize the global variables to appropriate values
# e! |5 {& w- x- z4 G% e, i7 Gto setup-globals: t5 l5 S1 g( o
  set current-light nobody ;; just for now, since there are no lights yet9 q! c. q$ U+ p9 K
  set phase 0
& f: s& X* u% j  z1 C# \" t  set num-cars-stopped 0, C  \  v2 {: w
  set grid-x-inc world-width / grid-size-x  i) R5 T6 k% l. r  Z5 m
  set grid-y-inc world-height / grid-size-y
) G( g; ~! l2 \& F/ \$ @  W
; c/ u: _* S2 [6 E- b  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary, ^' q6 u! v* h9 ~/ }
  set acceleration 0.099. o( Z& s. H7 l) [
end/ V' P/ Y8 x* O/ Q

8 D" p) R" K+ ]) @4 |5 A" k;; Make the patches have appropriate colors, set up the roads and intersections agentsets,1 q' e$ s6 @/ u0 ~1 N
;; and initialize the traffic lights to one setting; P& O4 i2 W/ E* m' H- I# |# M8 }
to setup-patches0 v+ z% j& L/ m  ^8 z. @. b. Y2 w+ h
  ;; initialize the patch-owned variables and color the patches to a base-color
$ w# T6 [3 t! Z  ask patches
0 J) g$ v+ y0 l- L0 S  [; U/ x( ^* N2 p7 u# Y# _" U: E
    set intersection? false& k+ |' m  ?! W! d' t
    set auto? false
. p+ P# J8 A0 N# p+ s3 f    set green-light-up? true' ^# t4 L( ]- Y( J! b5 f9 M: U
    set my-row -11 ?6 E  P" q" c: U, a  o
    set my-column -1. C0 Z" z; n5 x# ^- v% `, A
    set my-phase -1
$ h3 Y  w# r+ l- q1 X. J3 Y    set pcolor brown + 3
. i$ \/ N! d; [# I  ]
2 y. W' X( T1 M; V$ P, S
7 A5 c' v# I& ]8 T  ;; initialize the global variables that hold patch agentsets5 V+ I1 v& ^% M
  set roads patches with) ^) y: ~" |% G: ]2 F
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" y3 [. \0 l. I7 C& M% X3 ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& v0 z% s1 y& ^' J- `1 k
  set intersections roads with: [2 l' T, P: g
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
* y  z& |% B% I) u* n$ `0 B    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) T% h4 q0 k! {1 m6 h, Q
/ ]6 r3 I# n) c  ask roads [ set pcolor white ]( y" [) d" \- {9 b/ b# S4 p
    setup-intersections, u, ~% r$ f0 ^3 Z6 e( \6 k2 L
end) P; A$ K( t# [) `' `( d
其中定义道路的句子,如下所示,是什么意思啊?7 m6 J. D  I6 {( [7 s$ x# @
set roads patches with
! `% Z3 X( b/ t6 w    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* y0 j2 {1 Y' |
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 M+ w% L" f+ O: N8 ]/ i; s& D6 u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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