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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。& _# j7 E6 E; p( F5 t: w
netlogo自带的social science--traffic grid这一例子当中,8 a2 R8 ^5 _9 J5 |9 B) |! ^2 _( I, b
globals
$ \1 A4 T$ C9 N8 m% K3 f[
  X4 R* M) P2 J  grid-x-inc               ;; the amount of patches in between two roads in the x direction
, j$ l7 p' o/ H3 w# U3 e# F9 v  grid-y-inc               ;; the amount of patches in between two roads in the y direction0 [9 |% n& z  ]/ o0 l
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
# s: k- H( s$ C0 O5 J( U8 L                           ;; it is to accelerate or decelerate
1 ^& ~0 Q. f/ S- K& Z+ ]% l  phase                    ;; keeps track of the phase
( N" T4 S$ Z0 r+ N# v3 X  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure/ P3 a+ J- I; F5 I3 Q
  current-light            ;; the currently selected light4 o9 `4 B/ c' P2 q

! j9 J7 S+ _' _) ?- O7 n7 s& ]# C  ;; patch agentsets
! I9 Y. x1 ?, K/ p: P0 t  intersections ;; agentset containing the patches that are intersections
# B9 `3 V9 r0 S; w& i4 f& Q2 y* K  roads         ;; agentset containing the patches that are roads) u' u: M2 n$ s' e4 g+ L
]
# [  K2 H" y& X! v1 O' n9 v
4 V; u$ D! n: @5 P- u* ^% Nturtles-own; O  c8 X+ ~5 O* w
[# z9 k8 I8 M3 x( j, ^/ J
  speed     ;; the speed of the turtle
6 d. Y0 [/ u' w6 f  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
; @) }9 n% q" u3 n5 W  L2 r. J  wait-time ;; the amount of time since the last time a turtle has moved) X+ i, F# q3 J2 {$ d/ W9 W# `
]. C" a1 q) D. }9 _# _% K1 R

& O' d# c1 z$ M4 @- Y- Gpatches-own
# ~' H3 p5 ~, Z: r: m+ C+ ?[
7 W. J3 f# \8 `1 n- m0 m  intersection?   ;; true if the patch is at the intersection of two roads
" r: Q6 Y  A+ }; a  h  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
2 r9 P& {9 k; [8 S/ W6 t. e                  ;; false for a non-intersection patches.
$ x8 g2 k: D( R# D  my-row          ;; the row of the intersection counting from the upper left corner of the5 o% e& `! y& q) o' b' _0 {
                  ;; world.  -1 for non-intersection patches.1 ?- x9 v0 A- Z. |2 j
  my-column       ;; the column of the intersection counting from the upper left corner of the
+ r% E4 l8 ^0 Y( x& J# @                  ;; world.  -1 for non-intersection patches.
- Y( M( y3 y# q; F6 ]; N- m: h  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
9 {# Q( H9 n: U$ J  auto?           ;; whether or not this intersection will switch automatically.
6 g$ o9 }& d* S+ B  n7 F                  ;; false for non-intersection patches.. p* h4 C+ n7 k- S! G$ k# g1 k
]$ B: E5 C+ P2 P+ @9 x2 j

+ V8 A& `# y2 W* N. Z8 o) w: O
! M+ w  R4 L0 b! M( n0 `;;;;;;;;;;;;;;;;;;;;;;8 F$ g4 U* m8 S
;; Setup Procedures ;;+ u$ d  g" q- _. r% W
;;;;;;;;;;;;;;;;;;;;;;1 X# f. p$ _  m' J6 S4 q, N' L" _

# `% {$ D+ N' D1 R* S, {;; Initialize the display by giving the global and patch variables initial values.- e7 A2 \4 L" U& ^6 ~3 S. z
;; Create num-cars of turtles if there are enough road patches for one turtle to4 w2 O" D1 W# u3 B8 }1 G" Z& O  e" Q
;; be created per road patch. Set up the plots., F. S5 R. e5 ?& [. P- @
to setup. J) S3 f# \# Q5 Y, E; r
  ca
0 l# M' r2 B2 ~9 s; A  setup-globals1 p6 d0 S0 d- |: |4 ?0 O

$ c; g5 p8 W& `, S  ;; First we ask the patches to draw themselves and set up a few variables
  E: k( h0 ~2 w  setup-patches
2 b9 f; h. R' B8 u  make-current one-of intersections
: P& v$ q5 a2 z7 N- S. K  label-current# v. R+ F9 T9 Y4 Z

/ d/ _, r! U0 m# L" F# e- f0 s  set-default-shape turtles "car") P! w9 k$ k  i; t% g; v
- h. j# w7 U( q/ C$ q
  if (num-cars > count roads)
+ [9 C! m. y( @8 J9 e, C! R  [
4 j  C. C8 ~5 X+ x4 r8 z8 `0 }9 x" m    user-message (word "There are too many cars for the amount of "
$ C+ n7 n* j) s, j7 L3 ~                       "road.  Either increase the amount of roads "  Y: d& n0 i5 o
                       "by increasing the GRID-SIZE-X or "  o4 t! Y' y& }7 M0 C8 y% ]
                       "GRID-SIZE-Y sliders, or decrease the "* @  |9 f4 B" Y; e1 K2 H) w: i9 `
                       "number of cars by lowering the NUMBER slider.\n"
3 g& C: z6 I1 A$ e& O  p; Y9 t                       "The setup has stopped.")
8 D8 y( b( U# i# [+ m3 L    stop: e+ x1 R+ k* [# }7 [
  ]
2 ?6 l1 @1 i) N: c1 z% ~
) \* y7 }1 z( y! B  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color7 J% W' A4 _' ?3 Q) o
  crt num-cars% c% D5 Y! p% N& x
  [
# }3 ^# o# {' H* g- ~  Y    setup-cars
4 @3 \) `( L) C8 u1 s3 q' c    set-car-color
* |  j6 S, {* i3 D' D    record-data7 R' j3 m9 T6 O! m% E
  ]3 r- m/ v  x5 y9 U0 R; {" U4 H

! X; z- H/ k( K4 Z  ;; give the turtles an initial speed; C) n6 R4 |# ~  g6 ]0 n7 I
  ask turtles [ set-car-speed ]$ t+ ]0 ~; S6 F# _4 E
' D% Z# S0 o. p3 F& h8 t  \1 E
  reset-ticks
! U1 U$ T0 D6 z% Z( yend
6 L7 N2 n- V$ h+ q& P/ v4 p
9 ?/ I2 l7 l8 D8 \;; Initialize the global variables to appropriate values/ M& `. d6 \$ C& u2 ?7 t  R; j
to setup-globals$ i' X& p% |# U7 P  j* A; G+ p
  set current-light nobody ;; just for now, since there are no lights yet& E8 r: c/ y/ l' F; R
  set phase 08 k! o/ p( @* Y- Q' {1 |
  set num-cars-stopped 0- q0 y) F. B) y
  set grid-x-inc world-width / grid-size-x
5 f. b! u" h: p. Z3 s* f( j  set grid-y-inc world-height / grid-size-y; Z0 s# y: Y0 d+ c
& Z/ a# ^# H. m: S) @5 l5 K
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary3 |, B' ^- d+ m' H2 a! i
  set acceleration 0.099
/ Y% d9 v# d# |0 [) cend
' T5 B) ]+ M$ I/ ]* \
" ?0 x! i' p8 \9 J5 T;; Make the patches have appropriate colors, set up the roads and intersections agentsets,& X$ q3 M! m: Q7 M. S4 {( H; G
;; and initialize the traffic lights to one setting! e6 v+ f% d8 j) d
to setup-patches( j: s: z1 j+ ]1 u& o6 B2 B! C3 o5 e- i6 N
  ;; initialize the patch-owned variables and color the patches to a base-color
' G8 D  G$ @$ W  ask patches
4 s  c- `" I& V6 B6 w  [* p4 z$ g/ \; X3 t! ~# P
    set intersection? false6 l7 n" Z9 U* V! p" M3 _% Z
    set auto? false$ Z% o8 b. y5 l/ ^2 f9 J5 B
    set green-light-up? true: r) l4 G/ K/ i2 Q: \; S6 |& h) u
    set my-row -12 f+ r0 {. o2 I0 n1 Z. [
    set my-column -1
' n1 B$ ?1 H* f0 V; @    set my-phase -1
7 |: Q% Y& t/ g. [" S. [    set pcolor brown + 3
& k7 N' u  _$ f  ]$ I$ h. ?) m1 d6 [+ G* X8 L

' I4 \: {1 |5 s0 M5 l9 k1 d  ;; initialize the global variables that hold patch agentsets; i* j. g. R6 I$ v% i
  set roads patches with9 n1 \6 q0 }, m  _7 @- k0 E2 `
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
. M' M  k1 Y# h- \    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 e8 y! N) T0 a  P4 p- S+ r0 j9 W  set intersections roads with5 K" A- b1 }6 D: B
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
' n1 A1 u% t' G5 v( ]! M: [7 j    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 v5 A! R! e/ H& Q  I, C; `/ G  @/ ~3 s% {  a
  ask roads [ set pcolor white ]
' `. }' L1 j- t$ Y7 g    setup-intersections: |" k) Q1 x% n& C# L
end
' z9 G2 C& p. k0 x9 x0 o7 E3 o其中定义道路的句子,如下所示,是什么意思啊?/ c. T& O% F6 X- p( w
set roads patches with9 T; P# J5 O6 Z: Q# c6 i; Z9 L
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or1 u( H3 m" r6 q7 X6 @9 x: ~, R
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# d5 ^4 e4 r: w$ l7 `# \& j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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