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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。# M2 L+ \1 x; n+ |% N
netlogo自带的social science--traffic grid这一例子当中,
& K& L8 e: D; C7 k* _5 j9 F9 `1 m& gglobals
3 \3 \  b) \7 O& h  d  E[: _) B, ~) K+ X+ M  ?
  grid-x-inc               ;; the amount of patches in between two roads in the x direction8 f* v, E/ p, G
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
1 O) y  }4 O% n; r2 E5 W  acceleration             ;; the constant that controls how much a car speeds up or slows down by if2 [1 Q- I' {% H0 Y( b
                           ;; it is to accelerate or decelerate* c/ W1 D& G% v3 V" \
  phase                    ;; keeps track of the phase
4 D7 I8 o8 g) p  j3 L; a  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure& I: T! ^1 T. L2 ~
  current-light            ;; the currently selected light
- H+ J5 b, h7 w) m
9 ^2 _, r% R# l3 {  ;; patch agentsets! R: `9 N- Z3 Z3 m- y& O0 S8 x
  intersections ;; agentset containing the patches that are intersections! d4 F; s- M* V6 K1 F
  roads         ;; agentset containing the patches that are roads8 ?- ]2 s1 U$ r. Y# C; `
]$ K% O% {( B" q% h; \" |
, `/ Z5 ^9 {! H7 h3 N- L
turtles-own* o0 {8 m3 d8 `! q1 W
[
/ K! m0 ~: |$ e2 a3 R* A$ F  speed     ;; the speed of the turtle
( ~3 Q; h" b" r* x; o( ~2 e  up-car?   ;; true if the turtle moves downwards and false if it moves to the right& _. d5 `$ a$ j2 e
  wait-time ;; the amount of time since the last time a turtle has moved
' x$ B8 C0 @' `8 S  v9 p]4 y% I0 n% r9 A7 ?) |" j

- A0 r5 |0 R* U0 q# V# Mpatches-own# r7 U4 V9 [) `& u9 b* @
[
6 U  [$ W, M3 s: |# t- R8 E' n  intersection?   ;; true if the patch is at the intersection of two roads
$ z) V& X7 k! ~! C2 _8 u- [3 t  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
" V$ g  U' B2 k* D1 u- J/ w! k                  ;; false for a non-intersection patches.
2 m& Y% ?2 |# B/ p9 t; l9 n  my-row          ;; the row of the intersection counting from the upper left corner of the
* d6 Z$ z! s, C                  ;; world.  -1 for non-intersection patches.
; o# B7 {$ D6 C) k! f5 ^: I  my-column       ;; the column of the intersection counting from the upper left corner of the
* R0 D4 j% e( C8 y! ?( H                  ;; world.  -1 for non-intersection patches.
; p8 z! K7 M: c- D/ R$ b  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
% y6 ^6 ^9 q' h  auto?           ;; whether or not this intersection will switch automatically.& o. J# R+ m; @; p4 L1 F
                  ;; false for non-intersection patches.) R8 v0 ~6 u$ O/ K# x: t2 `4 q$ g! Z
]
# |0 d' D9 N+ O0 P2 M
" _1 Z/ ~1 q0 I, R6 ?
- G( F7 J$ [3 v1 M" K;;;;;;;;;;;;;;;;;;;;;;
- O8 j& @# _0 k" E6 s;; Setup Procedures ;;
& c- \' a3 y# p4 W;;;;;;;;;;;;;;;;;;;;;;
$ \( A1 q) w+ ~. U: \7 Q* ~
, v6 w& R+ ~5 R$ C8 C+ m5 P;; Initialize the display by giving the global and patch variables initial values.# B: c& p9 c. |% ^0 o5 ?
;; Create num-cars of turtles if there are enough road patches for one turtle to) j; l( G# F0 I7 Q! x) f# o
;; be created per road patch. Set up the plots.
% e% X& H" _) h4 o6 i0 M' jto setup0 v8 m1 `" D: o; [- K
  ca' U. U+ }" r% Y
  setup-globals
  |1 @; I4 k% Y
2 ^0 c. S: k7 w. W/ [4 r  ;; First we ask the patches to draw themselves and set up a few variables2 c/ ^6 `8 L1 Z* S3 m7 W3 H$ s
  setup-patches4 j6 y4 p( Z! V+ ]
  make-current one-of intersections* x9 v4 F0 g  R4 H% z: E
  label-current$ {; T: H8 }9 ]% I/ h
% ^$ T% M9 ?  R
  set-default-shape turtles "car"  b! ]3 p+ P. m9 j" Y9 ^% u$ g% Y9 ^

. M  i1 h6 w3 O4 o! A' p9 s  if (num-cars > count roads)8 X0 n! w" ]0 n3 d) ]
  [
" l; {7 m, r( x- I1 I    user-message (word "There are too many cars for the amount of "1 T' B# r/ {+ L% a8 h; T
                       "road.  Either increase the amount of roads "
/ r4 L* ~7 c7 \* j4 w                       "by increasing the GRID-SIZE-X or "
7 u4 u2 r1 T; @3 T' \1 R- s) [                       "GRID-SIZE-Y sliders, or decrease the "
0 M' {# n- \/ S" Z. h8 u6 p4 Z7 y  v                       "number of cars by lowering the NUMBER slider.\n"1 N% h+ h. G$ {; o! I1 t) V" A8 M
                       "The setup has stopped.")2 U! N  a8 [& s0 |6 ]2 y, F+ ?: x, a
    stop
% d* H" ]6 V; k6 S  ]
1 i. t& p! e2 X6 N/ `1 Y; ~' q/ w" m( \/ u$ `9 a" d/ c
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
' T* t+ V+ u1 W1 U3 s  crt num-cars
% q6 D5 x% a' |1 v  [3 p7 F' m: g# {# h5 o$ i
    setup-cars
& e$ X$ ?( [9 o7 T0 u5 C. a* r    set-car-color5 p+ Q- l4 V6 W1 l- b
    record-data
# S8 z2 [3 ?1 ?7 {/ L; U  ]
+ e# L+ {# g% B& E: r5 N* k
6 B+ \+ N4 I4 v# W% S* y2 V: {  ;; give the turtles an initial speed
/ b7 I3 @+ O7 `  Z  ask turtles [ set-car-speed ]3 J) l! O4 ]1 ?+ _0 t/ a3 V1 R
0 c& o" \: M. d2 @$ i5 V
  reset-ticks6 `0 O/ D8 H6 _# U
end- J/ w7 B+ a- ?- D: {4 Z

( l' W, b/ [; @;; Initialize the global variables to appropriate values: m. P3 m8 g- C
to setup-globals; X' N- d8 Z$ S% o
  set current-light nobody ;; just for now, since there are no lights yet
% a* }' ^$ G2 l! O" f1 Q* ^  set phase 02 I1 t9 n4 h- a& c8 K% j
  set num-cars-stopped 0& J! k9 U9 r, G1 X) d5 s
  set grid-x-inc world-width / grid-size-x: G+ b5 h% Y6 D! h  }9 t& e
  set grid-y-inc world-height / grid-size-y( N6 |) r: l) B6 D
2 R+ u0 u1 v9 m7 h+ m
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary1 j7 V# Y! Z( V# {( R- ~( r& E
  set acceleration 0.099
2 E; j. M  R+ ^- S3 uend1 f/ a" m8 ]8 b# f7 w3 K
4 X( A) _- D6 i# b
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,& }: N# {$ p" h9 a
;; and initialize the traffic lights to one setting
1 I* N/ D2 u( N$ l* U2 Y( Kto setup-patches5 O% V# A4 q0 i
  ;; initialize the patch-owned variables and color the patches to a base-color
5 U& X$ e  c; j; m  d! Y6 U5 o4 F  ask patches3 }9 m4 g7 H( f; v: {) Y( `" O7 J
  [
+ s; B  q& U5 D1 E6 A! z    set intersection? false) P4 X9 g$ ^5 X- v
    set auto? false
/ j; {8 a7 a" I4 N; x    set green-light-up? true: O8 V0 c+ A3 `* d/ q8 y5 G
    set my-row -1+ {3 B3 k: G7 _" S& z% M
    set my-column -1
% q( l) H9 b2 x! F    set my-phase -1) q7 t7 k  D- ?- R3 I- e
    set pcolor brown + 3
3 V/ K5 ]6 A" c! ?4 J8 V  ]
0 d5 C9 L/ \7 D& ]* ^
7 y5 ^. S1 O* I: k! Y  ;; initialize the global variables that hold patch agentsets* L0 Y1 t% C% X# I
  set roads patches with
  a/ [, m- r; k2 e; m0 Y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ L- ?5 ~) q. O% \4 v
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 @1 _, R. o, r. D0 y4 g  set intersections roads with! U0 F4 @$ j# V# D% R* l$ F( q: ]9 R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and% ?0 K4 J2 g2 m0 I1 R8 o
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. M  f; O0 c* x( F
: u2 }, k& [& m: e# ~
  ask roads [ set pcolor white ]6 y: v+ q- X% e! m6 q7 K5 ]
    setup-intersections
2 u8 B: V' A# p' Zend1 T% n2 o) A  ?# ?3 _6 I+ x* p
其中定义道路的句子,如下所示,是什么意思啊?
  o* G" q5 d1 ]8 h" w3 g" w set roads patches with
2 E3 d" D0 d8 p2 x$ _    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ A# P- m0 j) H
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 A' S( b$ E; `$ u. C2 @# w$ K, D+ p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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