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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 G4 J+ c$ g; F
netlogo自带的social science--traffic grid这一例子当中,) |% H* f+ h4 L5 f4 U5 [: o
globals
! s8 N' A" b! I$ Q/ Z) w- m[
( n+ J! n  P9 Y1 D/ A  grid-x-inc               ;; the amount of patches in between two roads in the x direction1 [: }4 u- Y5 i3 V$ x8 q
  grid-y-inc               ;; the amount of patches in between two roads in the y direction7 K3 M' O/ }  c' L
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
- o; `0 _( K8 Z3 M. h9 J5 Z! v8 U7 u  ~                           ;; it is to accelerate or decelerate* [- g' O% {( D* {0 `0 ]. k' F- W
  phase                    ;; keeps track of the phase
! Q9 G5 ?, s3 [0 r  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
$ c% z' w* `! @. X% C  current-light            ;; the currently selected light
& k+ w( \- B! ?& ^- @6 y9 H5 ?8 s
/ C# G: ?6 I/ N) V  ;; patch agentsets
5 S; p; A& U& B( F, q- c  intersections ;; agentset containing the patches that are intersections) F0 h& z0 ]. m5 [# m
  roads         ;; agentset containing the patches that are roads0 v) m# l8 h; \& w6 H, A
]
9 k  E2 Y# K" n2 I* F9 l( j9 T; F; U1 V! w
turtles-own2 I5 S/ ?# }$ D! b3 Y
[5 G1 H' n4 X3 }( R
  speed     ;; the speed of the turtle4 n5 m" E: a' j) K
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
$ ^2 U7 F$ w7 I) O  wait-time ;; the amount of time since the last time a turtle has moved
# l& _9 i& T+ b$ K]
+ L( S! J  ^2 F+ w! i) p, O7 h- }0 ?" o: p$ z
patches-own
. S# C+ l9 D. ?5 a[
  V9 v6 i& |( G; H$ v  intersection?   ;; true if the patch is at the intersection of two roads3 B/ r  p8 R/ r7 x7 `0 u4 C
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.4 i. K6 c6 a+ S9 K7 d
                  ;; false for a non-intersection patches.7 ?$ p$ @) @0 i
  my-row          ;; the row of the intersection counting from the upper left corner of the! z, \# ^6 x0 B
                  ;; world.  -1 for non-intersection patches.1 @; t% B, w) @
  my-column       ;; the column of the intersection counting from the upper left corner of the" f- p/ b! U/ Y/ [
                  ;; world.  -1 for non-intersection patches.: W+ H9 X* p. w
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches./ Y1 M" I# |) p7 P! ~' N
  auto?           ;; whether or not this intersection will switch automatically.
2 K7 P. F0 F4 z3 `; W; A                  ;; false for non-intersection patches.
( ]9 t1 I" F. f% y# l]& n1 V2 j! o# s* o/ u& z: _
4 r9 H2 K: N' F( e! j% S0 V

! V3 \5 j, \" [7 j;;;;;;;;;;;;;;;;;;;;;;
% W1 o7 j- R3 ~8 k6 n;; Setup Procedures ;;
* \6 w( Q! O+ A0 G* J;;;;;;;;;;;;;;;;;;;;;;. X7 q! u( V; }: P

5 b- A0 {& I% H7 R- O;; Initialize the display by giving the global and patch variables initial values.1 u5 G- C# a6 E. M
;; Create num-cars of turtles if there are enough road patches for one turtle to
% v# a) J/ p+ L' B( ~9 i;; be created per road patch. Set up the plots.9 x( d& b) c: E' U3 s& Q- I
to setup0 v: j# k2 p) z# b( Q7 I6 C: h
  ca9 {& y5 x+ {9 ~* _
  setup-globals
' u8 ^) R1 l& Y$ H  O. j* B3 \7 J% X% y% S3 O* M
  ;; First we ask the patches to draw themselves and set up a few variables
) E: }7 @. ?/ d/ p2 f  setup-patches
' w! t, O& Z! z  p9 A9 ~- ?' n  make-current one-of intersections% s$ g4 q" d6 R7 O  c3 ~7 s, J7 q0 s
  label-current% I8 O" N3 C6 Z+ y; X. Z

6 T8 w' r5 S8 u! @6 K) f% J1 ~  set-default-shape turtles "car"2 ~  a3 g5 |4 X1 {( l
2 ^7 H9 [5 `) i4 U5 c
  if (num-cars > count roads)! }9 T, Q# n( J+ B4 J+ [1 g
  [- _* v' E& i% @; |+ ]
    user-message (word "There are too many cars for the amount of "* w! x" [; k1 C6 N% t! [
                       "road.  Either increase the amount of roads "
' e- n: y  D2 g0 m( |& _* H9 Y                       "by increasing the GRID-SIZE-X or "! e$ I' K' f) p! r
                       "GRID-SIZE-Y sliders, or decrease the "
6 d% b3 W4 n* F- d9 c                       "number of cars by lowering the NUMBER slider.\n"9 |) `* C) y( F, K
                       "The setup has stopped.")6 x# S7 K/ _$ ?* j- i2 K
    stop, o7 B+ y- ^9 {$ ?( q# T
  ]' ^: j+ K, ^" I* ?3 V7 l3 y4 h
4 ]  H% V. L+ }2 l9 \
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
  x% w" \* W1 P, V% ]' Y  crt num-cars) R) r7 i, ]5 l9 A
  [% o# R3 Z$ m8 u7 D% x0 ?- d8 p
    setup-cars  [) {; u) f0 p7 X
    set-car-color% [- h# \" `4 H6 d! m3 i
    record-data/ u2 J: e7 t' N* T: ?* [, J! F
  ]
, @0 r; n; \( u3 t9 W
1 T: Y; _9 K5 Y; p7 `) I  ;; give the turtles an initial speed
0 K1 Q1 c( Q' O  ask turtles [ set-car-speed ]3 E- y& \9 |0 m4 j) }' R
3 B" I0 ?4 Z: ~
  reset-ticks
6 T( g: X! d. p+ `end
3 H8 m  B! H  y+ {4 q, g5 x. p& ?, F! i% g( D3 k" t
;; Initialize the global variables to appropriate values
$ \7 x+ N; v$ |' w* a, A* Gto setup-globals
5 |2 A- Z: K3 I9 ~- K  L  set current-light nobody ;; just for now, since there are no lights yet  ]7 Q) l0 W8 K1 L. T/ g1 G
  set phase 0: \5 N+ t5 B4 j; I9 Q/ M
  set num-cars-stopped 0+ h2 `6 i' F" Z* c
  set grid-x-inc world-width / grid-size-x& G$ ?- E1 o9 I- c
  set grid-y-inc world-height / grid-size-y- |/ G* k9 z- P6 {" b: H! ^! M( M8 y

9 g2 q$ {0 e  H3 x% L  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
/ b9 D( D2 |) V8 w  set acceleration 0.0990 c, [4 n+ c+ P! h& [: C
end
9 c! h  [' w& }8 e1 X+ p  A
5 s5 n; [( k% r0 \;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
2 E, D5 q, C3 J- r  [" x+ E5 Z;; and initialize the traffic lights to one setting
: V/ e- I  N4 _- m4 I1 `to setup-patches
2 Z) b8 z+ H( c# L  ;; initialize the patch-owned variables and color the patches to a base-color/ [" Q" l4 \4 U0 Y
  ask patches8 y  ]7 R" e, n$ v( h
  [
8 u1 G/ b% }1 W: N( ^8 G    set intersection? false
5 S/ n! T$ B. k4 N    set auto? false% `% h7 [3 O5 l
    set green-light-up? true) i- B6 l0 y- {3 D+ V5 d+ N
    set my-row -1  N/ Q1 P0 {7 z8 D+ ]' l; l
    set my-column -1% t" |4 J: ]7 G4 V( N1 Q& J
    set my-phase -1
' [, F8 x4 @: E# K( ]    set pcolor brown + 3
/ E- H# m9 y; m; n1 H( M/ p  ]
+ f$ @" f4 Q) x- Z( A# B) M: P1 C- d) [$ l; q- Z$ ^
  ;; initialize the global variables that hold patch agentsets
; T' O: Q9 L& m/ `  set roads patches with8 o6 @, e) I/ E; w
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 A3 e: U% Z7 d$ x0 |6 ^' i    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 ^  u( p. `, D8 P/ H  set intersections roads with
' B" U. f0 v, }7 t, X    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and" H  H) ]0 K- z7 Q& `3 y; \1 X
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# [5 |# k/ ^5 `$ o4 ~2 n
6 v# _6 F( @0 g- c# E
  ask roads [ set pcolor white ]
3 `) z4 ~! ]9 A9 O3 e" J8 v    setup-intersections
( ?6 a, B  `" U$ e- Y1 zend
: r' d; r) v3 z5 P; R其中定义道路的句子,如下所示,是什么意思啊?
7 |& j1 C$ [' j3 [( k/ q set roads patches with
$ [1 _* R: }' T( W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
: d# N" s! N, s! s2 ?. B  Y8 C* u    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 Z9 H  r" A, m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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