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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。. |+ |& V. k  C. J' I
netlogo自带的social science--traffic grid这一例子当中,6 A/ y1 {/ p4 @+ H' n6 K5 g
globals
! _, f# F) O! f: U5 D[& x! _. d, J6 N
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
! K& L+ m! {( t6 p  Q  grid-y-inc               ;; the amount of patches in between two roads in the y direction! }0 m$ `/ _. w& f4 Z6 I1 G
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if- V4 B4 `6 K* b! N+ g
                           ;; it is to accelerate or decelerate' H& W- [3 c# b2 e( O+ V! k
  phase                    ;; keeps track of the phase8 {4 |6 F; Y' t/ ~+ k2 i
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
3 I' H% T0 U- X4 \4 J8 b  current-light            ;; the currently selected light
+ H5 \9 C4 W# ]3 Z& p9 ~3 C. V8 w) K2 Q' r  A% I. G4 V" D/ z
  ;; patch agentsets
- H0 i1 z/ P2 i9 L6 D  intersections ;; agentset containing the patches that are intersections
2 ~% t+ F4 j( {+ f" ^9 M( u  roads         ;; agentset containing the patches that are roads! j$ P; B6 Q& B6 n3 `2 J* \6 J
]8 k2 ]9 Z) Z6 f) Q: Z; J2 A3 K% O

( N) B/ ]9 p2 E6 Mturtles-own4 C  }  S) f& {( A( T5 i& D" q
[
! J! y/ A" z' S% J8 |, f1 k  speed     ;; the speed of the turtle
  r# P7 ]- O% X& y5 b+ a) d  up-car?   ;; true if the turtle moves downwards and false if it moves to the right4 p6 T6 n# c# @
  wait-time ;; the amount of time since the last time a turtle has moved
, S1 p; }/ K  z$ \" F" Z4 Z4 I. _]
3 b6 C# h% \! k& n- c: ?/ L* D( h  @
patches-own
* j' G  K# f9 i- c9 j" P[- J$ o9 Y/ L0 x, M9 L; c
  intersection?   ;; true if the patch is at the intersection of two roads7 t" x% [9 f( C9 I
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.# k" n! [! T6 y- y4 u7 X8 v2 p
                  ;; false for a non-intersection patches.
8 G$ s, s/ R; s: m  my-row          ;; the row of the intersection counting from the upper left corner of the- ]% {" o8 @- O8 P5 j' L! z
                  ;; world.  -1 for non-intersection patches.% ]# o8 P! x! q$ Q: ?
  my-column       ;; the column of the intersection counting from the upper left corner of the
7 H  t$ H/ k& L( T& ~                  ;; world.  -1 for non-intersection patches.
  m& a% X$ e9 T% v# h1 p& K  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.8 |1 A* |" B$ z1 j
  auto?           ;; whether or not this intersection will switch automatically.) ?' ~/ A4 T; N$ o
                  ;; false for non-intersection patches.+ n: ]: D8 e, x% O# `* T# K! ^
]% D6 J1 k, j* o8 g# O  P

, Q( Q7 s/ P1 ?! j) n
- Z7 h" e) a& C* q& H% n* s9 f# `;;;;;;;;;;;;;;;;;;;;;;  B7 @; F0 k/ d  g: F3 k
;; Setup Procedures ;;* `& k! l( l5 @$ j1 R
;;;;;;;;;;;;;;;;;;;;;;
0 a) q. z, S$ e" j
8 U- X2 P- i: p* }4 Z  \;; Initialize the display by giving the global and patch variables initial values.) R; Y$ N5 z: M' Y
;; Create num-cars of turtles if there are enough road patches for one turtle to
: |/ p) z8 R9 j5 `+ X3 ?- Z- J;; be created per road patch. Set up the plots.
" q6 o$ b' D2 {9 H+ U3 O1 Uto setup
8 O6 y9 k8 {. w3 f6 m  ca3 {' k4 q3 m2 T7 Y1 o$ ?+ T
  setup-globals
  x1 {% c; s% y5 K9 x
* r0 h' P# V1 ?) y  ;; First we ask the patches to draw themselves and set up a few variables) j4 c2 S+ U( u1 \* y
  setup-patches
( Q( {* D2 D, r, S8 Y  make-current one-of intersections4 m( |) \+ a* c; O0 R, J8 j
  label-current
+ v2 E/ B, F; c9 m4 o$ C' j
- d0 l) G/ {2 H8 P/ t% a5 h  set-default-shape turtles "car"4 I- ?8 {0 C! Q; d9 ?5 ^

+ U7 |+ @/ q$ Q* ]6 n  if (num-cars > count roads)) N7 t8 W& r$ u, R8 y
  [
& K6 H1 G3 Y7 w" w    user-message (word "There are too many cars for the amount of ". a- o$ t. H3 P. R" j
                       "road.  Either increase the amount of roads "3 @8 `+ Z* U" O/ w7 ^
                       "by increasing the GRID-SIZE-X or "$ {  j( C% X1 J4 Y; U' K9 `
                       "GRID-SIZE-Y sliders, or decrease the "* ~+ @3 S9 Y! i" E
                       "number of cars by lowering the NUMBER slider.\n"
/ F$ E# G  p& x7 p8 k* c                       "The setup has stopped.")
9 }" R$ D& M  H! Q    stop- A9 o- e5 v9 o7 {( n5 S7 e
  ]+ h7 H( `- t- |0 H3 t. X( v- T) g6 ]
5 R% S: b* M( i: w, m7 k& F
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color$ p5 T* A# G4 `2 \. P( ~
  crt num-cars2 J4 A6 i0 N% E  o, D+ g. r
  [
& o  l. V0 z' D1 r    setup-cars
3 c& u& g# U! H; n5 J    set-car-color
! ^, Q# s, W" ?: I    record-data# w+ L& a: {- T2 A) b% v
  ]
# x0 ]5 W" I# Q) [$ T8 f: @" g
' d( x* L5 g  h- v& U  ;; give the turtles an initial speed: ^( y7 Q' I. R" B
  ask turtles [ set-car-speed ]
" R* l0 q% N" M' J5 g9 \1 k  H4 n6 R+ V. H4 ?* R  L
  reset-ticks; D  f$ k/ a# D  Q
end$ v# \% x8 x& p( V2 F4 y

) e2 H# u" t$ Y- o% a& E6 T;; Initialize the global variables to appropriate values! e" g7 R3 }2 x  \6 R7 r- m" c& n; A: ]
to setup-globals/ Q! D. P0 I* ~0 `2 _* j3 _
  set current-light nobody ;; just for now, since there are no lights yet
, w. ^3 g. W* x+ Y  set phase 0
3 U+ N3 m8 Q' }) q2 Z! e  set num-cars-stopped 0
0 G! j! Y$ B( c& n  set grid-x-inc world-width / grid-size-x8 l" o: E7 p. ~  Y2 Y# k
  set grid-y-inc world-height / grid-size-y
4 P1 R4 r* A7 E/ Z' U. Z  P$ `7 D1 o
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary& W, G6 c3 U# b+ e" k/ u
  set acceleration 0.099; T% R! A, Z+ ]) D) F. H* b
end
  I- g* v$ a1 f
- h7 R+ I: _) u7 [3 F2 Y;; Make the patches have appropriate colors, set up the roads and intersections agentsets,  W5 @; F6 {& A: \- t/ i5 c( T! o
;; and initialize the traffic lights to one setting
. H# k' `$ a0 H6 gto setup-patches8 G7 T$ R4 t7 U+ k# n9 M7 j: a
  ;; initialize the patch-owned variables and color the patches to a base-color
+ O# P/ }; l- `& }  ask patches5 J& g& }" D# P+ ~' p
  [
9 [7 Y8 T. `  O    set intersection? false' d7 P% H3 V9 J# R. W3 b: M% t
    set auto? false
$ H" g' b" F' `; @    set green-light-up? true
- c' {4 O1 S' N: K2 z& t    set my-row -13 y( o- @) ^8 q! p1 c+ Y1 m
    set my-column -1) f/ P! m+ {% \1 y  ~7 ^, w
    set my-phase -1
6 j, o! T  l2 U6 w! _    set pcolor brown + 3/ k+ ]8 z- @0 h9 Q) u
  ]0 q$ S. I) O$ p! r* H- L) ]" }1 B
* Z! G! ?  h2 k3 {
  ;; initialize the global variables that hold patch agentsets
7 }' T5 o0 M0 z' ^6 v5 Q' G' Q  set roads patches with
; o1 {9 R( H7 E+ c' O' f    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 e8 N6 E7 p% }" o1 \, E
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 e$ z2 |+ {7 w  set intersections roads with, r: d9 _( Z4 u7 t4 h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
7 }7 t& K. i$ q2 p% Q4 O! n    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& @, o; d: w" C/ f+ A. W5 k6 e& g0 F& Z: I# H
  ask roads [ set pcolor white ]
4 |! N/ {9 |1 R+ t5 B- ~    setup-intersections
! f2 O3 r. z& Y0 `end
$ L, f# [  |' S# g4 D, p7 K其中定义道路的句子,如下所示,是什么意思啊?9 v/ Y$ M* d8 J+ s& C0 R
set roads patches with
& k( w8 F5 z# r( p    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 Z; l, e  T0 B) X7 @; C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 W" K3 W- P* T& T) W2 [) O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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