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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。: l/ e, ]" W# z$ E; z7 h' ~( h
netlogo自带的social science--traffic grid这一例子当中,
$ G+ r4 J  o3 Y# O3 R0 T" ^globals- B$ ~$ B, ~0 G) _  V
[
0 d8 b0 R6 ?' }. z; Y% ], B  q3 y  grid-x-inc               ;; the amount of patches in between two roads in the x direction
& k6 r: e! W- c. X* M  grid-y-inc               ;; the amount of patches in between two roads in the y direction
0 {/ {7 ]! _7 b  o2 V* [) ^: O5 p  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
5 a7 w' m8 ~$ l                           ;; it is to accelerate or decelerate$ s+ w/ E& d: ]$ I; Z6 o
  phase                    ;; keeps track of the phase- ~0 s$ p  J- G/ `, C* \+ K' F
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
5 m* A' O: A( ?  current-light            ;; the currently selected light8 N# m0 D- A, J0 I4 D  z
  q. m5 K/ N; e3 k/ V; V4 @
  ;; patch agentsets$ ]! ~4 a8 c' z! y& ~
  intersections ;; agentset containing the patches that are intersections
/ [; b( j) M& h- q( B; N7 K  c5 Q7 t  roads         ;; agentset containing the patches that are roads+ x+ v  u+ W/ z1 ^
]
$ ^: l; f- B. Y: l
, v2 x2 C$ [6 l8 \turtles-own+ n. j  S9 ~- B$ ?  ]1 t) X
[
4 v  r5 U. P) O  speed     ;; the speed of the turtle" J6 p- ]3 e6 C4 b' i) Y
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right9 P5 Q- c. Q. ^3 R* ]3 h$ f
  wait-time ;; the amount of time since the last time a turtle has moved. O, C+ a: T8 V6 Q; A7 U# G( @
]' i6 ~* _  \: x+ y. z

7 G. f; _2 G0 p5 ]/ p: @patches-own
* v5 V- v7 x3 _. p[" m+ ^$ _& e4 l) F6 X6 _4 K) \
  intersection?   ;; true if the patch is at the intersection of two roads
% T, N% F7 W6 F% ~  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
/ g- X6 S- W' r5 Y8 j6 M* }( V7 E                  ;; false for a non-intersection patches.8 G5 w5 F; \  Q
  my-row          ;; the row of the intersection counting from the upper left corner of the
6 Y) i; w, H4 w& M4 H8 V- [! O                  ;; world.  -1 for non-intersection patches." n0 R6 A  t2 \
  my-column       ;; the column of the intersection counting from the upper left corner of the
; M1 x: _2 f/ B0 O                  ;; world.  -1 for non-intersection patches.
( a5 L  a1 C* O/ i% E2 F/ m  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.+ v8 h) E: e2 Q# t5 |
  auto?           ;; whether or not this intersection will switch automatically.
- r3 j0 k3 C) z6 U5 A                  ;; false for non-intersection patches.- a% |- Y  p5 ]) h4 j
]
$ Q1 Z; d1 D$ ^! o
: S& b# K9 [$ {4 g3 s
& F1 u, w7 e9 d6 C- z;;;;;;;;;;;;;;;;;;;;;;4 L& z# p3 ~. s# m* Y
;; Setup Procedures ;;
! u; ^7 [( A" X3 d! b5 Q7 ?;;;;;;;;;;;;;;;;;;;;;;
% \# h6 N1 u/ K9 M" {+ B* v! Q. C: r
;; Initialize the display by giving the global and patch variables initial values.1 c/ l: X5 E& O3 n% m: u
;; Create num-cars of turtles if there are enough road patches for one turtle to, i5 [3 p) M' o4 y5 W8 S2 {4 S
;; be created per road patch. Set up the plots.
& ~3 x2 Z2 M# E$ D7 e: pto setup
/ s9 {4 C# c: |  ca5 w1 u- ^& [+ O& q8 }
  setup-globals
. E. y# p9 b7 }1 G3 g! l& C3 ~7 u: e% A5 ^& W. f- l/ T( [
  ;; First we ask the patches to draw themselves and set up a few variables
  J- t( q9 U3 T4 _+ v, Q- N/ r& \9 _  setup-patches) H# e% |( w4 I, ], i. H# G. \
  make-current one-of intersections1 A: Z) e5 K& j7 b2 a
  label-current
; J% _4 |- b0 g: Q& _9 c# N3 J
% o) ~1 J  T" f! S- X3 z9 `  Z* r6 {  set-default-shape turtles "car"
$ z# ^6 e! R$ h4 p, V
1 Y. S% p4 y8 S! J) j( d. m1 f  if (num-cars > count roads)' x9 r' `( S8 V
  [
$ t- \: u: `4 x" _    user-message (word "There are too many cars for the amount of "
' J9 B, j  L% k" |: x" t0 K                       "road.  Either increase the amount of roads "% ^6 h2 ]( z/ u' ^0 Q3 }
                       "by increasing the GRID-SIZE-X or "6 r& n: s0 \4 {( N& l: G* ]0 K6 ^
                       "GRID-SIZE-Y sliders, or decrease the "7 M# d+ Y' [$ ]  C3 p
                       "number of cars by lowering the NUMBER slider.\n"( u& z+ K) M* F
                       "The setup has stopped.")
2 P3 c1 \* [4 L( s    stop- L$ y) ?# }0 ^$ C0 I
  ]
) |; E/ o  z9 D! d9 C+ ~
1 ]' i) n$ h( x( `: H) {  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color; e* ~+ ]; R# a  I4 [  A
  crt num-cars! r1 y: e4 `& F5 q1 X4 T2 I- Z
  [
! Y* o: m0 X, a; H# g, \- A    setup-cars
- [" m! t( {: d2 e5 b    set-car-color
0 U1 J8 F* p# U9 `% h    record-data
6 \; i4 h. w- V$ s  ]
5 l- V: b7 T4 C$ k$ A' ~
/ ]: K' Q  k! C+ ^  ;; give the turtles an initial speed3 i6 |( b( I  U  R
  ask turtles [ set-car-speed ]% X2 \4 V* X% h8 u: q
8 j. U  c4 E! M
  reset-ticks
, r. a, y% w. y/ r( z8 Iend/ r8 s7 {/ Y& h( e; Y; Q* P

' t7 ^/ y, `+ j2 N;; Initialize the global variables to appropriate values
+ R$ y& F2 o+ q0 U2 ~+ L# ?. |. Eto setup-globals/ h' G0 C* r- l0 G. `' r) T: D
  set current-light nobody ;; just for now, since there are no lights yet
& W  K" ~7 a% i9 P2 G* a  set phase 0. A) D( f, O$ |) c3 d. k) Q% M! P, V) Y
  set num-cars-stopped 0
2 K! S7 x* n; K7 L) q2 q  set grid-x-inc world-width / grid-size-x
5 x: d! H1 Q7 F* `* w5 Z  set grid-y-inc world-height / grid-size-y
7 F4 [5 J: v. x3 v/ a6 m. Q& T: ^  i" B5 O: ]( r7 y
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary5 X$ R) A9 G0 B+ l
  set acceleration 0.099
( y# Z7 L3 p0 h9 Nend
, h) H: T6 W' H0 u
3 U5 i: o8 d' T  }* E;; Make the patches have appropriate colors, set up the roads and intersections agentsets,4 O" A, h4 X4 _8 B2 b0 t. x
;; and initialize the traffic lights to one setting
' z* ^4 j% N' g/ U& K8 _" i7 pto setup-patches% G1 o- Z! t9 w: ^- b, h
  ;; initialize the patch-owned variables and color the patches to a base-color
5 g: z! O* a; k9 R  ask patches  U4 e' o  E( A1 I( C4 ^3 I: W
  [
! B; V, U! X7 {, r6 {( d7 X- S    set intersection? false# j$ Z8 n" Y0 U$ F1 z6 I4 j
    set auto? false
5 t6 w( `0 [+ U. \+ C8 p, Y7 o( {    set green-light-up? true
# W+ Q6 a2 j# W* C0 N  k& A: Z    set my-row -1
- ]$ O; @; ], o1 P' A    set my-column -1; N9 C6 p( M) w9 r: F; G
    set my-phase -19 R" N9 }; A0 s: J
    set pcolor brown + 35 ^6 k+ G4 n- g7 n) q# z
  ]
' v# R; ^4 o! R0 p  F# N
$ W2 U. C7 z, w; r/ C: ?, G  ;; initialize the global variables that hold patch agentsets5 n9 a" r* k: Y- Y% a4 w
  set roads patches with
% s7 z1 V: I3 [1 Z: z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" L2 w* I# w. w7 o" q. v    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ |* r/ C9 q& ^- m* J3 _1 \  set intersections roads with, K. N5 |, l0 \
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and, ^: |/ l: H% U/ ?; O
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 ?& N" X* e' b- p
3 N8 g7 S7 w1 z- f+ t% T  ask roads [ set pcolor white ]
9 Y, d2 w/ \: [/ E  X    setup-intersections
% p' J  C1 b. l* xend
0 ?3 H" W( D0 d) ~; \" o  \其中定义道路的句子,如下所示,是什么意思啊?
7 G7 x( q( D( }& @3 r8 \: [6 n( W set roads patches with4 o( c. X0 |) [. w
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% \/ Y' M' u% ~4 L    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 f0 ~3 V2 }! }8 B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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