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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。- u( {/ r- {# j2 @& |
netlogo自带的social science--traffic grid这一例子当中,
: I  s, p, `, |1 B$ ~( v% t& iglobals7 U; K8 I  n6 j# y9 u' E
[: h3 z6 J7 b, {: z
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
! H3 w7 b* x, a$ c1 z  grid-y-inc               ;; the amount of patches in between two roads in the y direction
3 R% ~3 F& d3 a  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
+ U# X) b! ?6 T1 W4 ^( H                           ;; it is to accelerate or decelerate
& {0 k) o. d: I5 S" X  phase                    ;; keeps track of the phase
- O  v; Y  i* Q$ O+ [2 P  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure: u* j+ k( P5 W2 ^' _* z4 F9 J! h
  current-light            ;; the currently selected light
" p' K+ e0 z$ E# P2 U2 y
9 c6 r! W/ K/ J  ;; patch agentsets
( R" [- m" X) T  intersections ;; agentset containing the patches that are intersections- b9 q5 o4 C6 }4 ^: A! |4 u/ n
  roads         ;; agentset containing the patches that are roads& w1 ]6 Y! d3 j7 _) I
]: i: ^7 Q0 y6 K1 _5 t

8 B- [( |* g/ s" x: hturtles-own2 x: u% Y) K; j2 `/ k
[& e' @7 `3 }' \: F8 E& Z2 g
  speed     ;; the speed of the turtle
  [" r/ {$ W5 \4 \$ c: w  up-car?   ;; true if the turtle moves downwards and false if it moves to the right, Q' f) X7 v7 i* q
  wait-time ;; the amount of time since the last time a turtle has moved
& l, Q2 f# @5 u" i0 s5 h# b* y]9 y& n7 q8 U; n) D# ~" _- \

) o9 H/ C3 s$ ?, fpatches-own9 n: A! N! d- l! P
[; o) Y+ y, H1 M  f& ?6 \, V
  intersection?   ;; true if the patch is at the intersection of two roads. p& L. e/ w( Y
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.9 x/ t- R3 w" N
                  ;; false for a non-intersection patches.' B+ u$ F1 S$ \5 F+ ~3 _
  my-row          ;; the row of the intersection counting from the upper left corner of the8 ]& |! M$ g$ ?8 g* y7 m
                  ;; world.  -1 for non-intersection patches.
7 _. v" [( b" c5 n' R& w# ~' D  my-column       ;; the column of the intersection counting from the upper left corner of the
5 V* [$ A- [2 t% s/ F7 {2 ?                  ;; world.  -1 for non-intersection patches.2 v2 ^  E/ r, K# c- x
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.$ T! C# ]1 k$ W  ^
  auto?           ;; whether or not this intersection will switch automatically.; S& ]( i" ^( n) Q/ |9 {) S# B
                  ;; false for non-intersection patches.
8 N, v0 h" J( S5 e]' h* z) L$ G& t$ d7 `8 b# n
5 M- v# n' ^! |# C# m; w# K

5 `- y* p$ i( l& j4 n1 C;;;;;;;;;;;;;;;;;;;;;;
: ]$ O( }; V& w3 M;; Setup Procedures ;;
' n/ ^: R' o  D, d. g;;;;;;;;;;;;;;;;;;;;;;' \! {5 }. k7 t% k1 ^
3 g7 v/ j3 e( p! T7 `( n: p
;; Initialize the display by giving the global and patch variables initial values.
) v* ?3 Z2 J$ {7 m4 c$ ~9 j;; Create num-cars of turtles if there are enough road patches for one turtle to$ h# K7 ]; n0 j
;; be created per road patch. Set up the plots.' f( ^6 ~6 I) i4 K, f' W
to setup& M5 y' f/ d4 }+ E  x
  ca( K: n# l* _6 o' w
  setup-globals1 O' H- T7 s! t& N& K5 b
, T9 v% T6 G  Y& L" r
  ;; First we ask the patches to draw themselves and set up a few variables
3 Y3 r( i" M7 [# o7 a  setup-patches) L1 a# G$ O; w
  make-current one-of intersections. c! h# \0 m5 b) o; `
  label-current
0 O6 b5 B" C0 C! [+ i
) ~0 t6 O: X# t, z1 |0 @+ q8 K4 c. ~  set-default-shape turtles "car"
- i4 V6 ?/ `" D% Z( K6 N: y0 P6 l0 F/ Z( \: i
  if (num-cars > count roads)8 ]! Y& j1 E( H2 c
  [
, A- l3 }" y/ I% E3 w    user-message (word "There are too many cars for the amount of "
! ]* t7 L" |( u4 Z0 V' z* y                       "road.  Either increase the amount of roads "$ k' {% r9 i1 Q
                       "by increasing the GRID-SIZE-X or "
8 I7 m( M$ z6 Y8 F' o1 i                       "GRID-SIZE-Y sliders, or decrease the "
& u2 G' @" s9 m0 k( \                       "number of cars by lowering the NUMBER slider.\n"( ?) W5 _$ |7 {
                       "The setup has stopped."): i: M! G# \) A
    stop
: _8 V+ p) k. Z8 b- ^0 s  ]: @/ H- g+ S- j! j
  a7 n* {9 B$ L9 b$ t5 I$ I4 Y
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
! U# _5 @3 s* \; E  crt num-cars, T! o8 L# e- B- e
  [* r; z. T& B) P3 ~# }$ q
    setup-cars* m3 u% K, Y/ c! k, m2 k, Y: H! z
    set-car-color
7 H9 a1 h9 ~4 z/ d0 P5 k$ ^    record-data
# b" k: r6 ?+ }+ @; I  ]
: O0 v% ~# U+ z% h! i2 T, n! k0 t1 F% |+ W' P' A1 e# T5 [- @
  ;; give the turtles an initial speed
! C& k0 Z# f. I' X5 s, r% i* }  ask turtles [ set-car-speed ]3 F) ~& H' j# V

" I+ p9 A0 I1 R; B& C9 y  reset-ticks1 }- Y4 E# A9 G3 G, P$ ?) x' |; ]
end0 Q9 z* F1 P! i, I6 X
6 s5 Q8 u  s7 C3 e
;; Initialize the global variables to appropriate values
! v+ x3 B# |" `9 V8 `: n1 bto setup-globals
$ B( W1 W' h9 W- ]( ?  set current-light nobody ;; just for now, since there are no lights yet
! O0 _8 ^( U! b* O. A, H  set phase 0
. M0 O" J- ~# F5 o. C: B  set num-cars-stopped 0
' q+ Z6 a6 n. f! n. W. F# v2 l9 J  U  set grid-x-inc world-width / grid-size-x7 _* ?" w0 Y" P* a, d
  set grid-y-inc world-height / grid-size-y8 j$ _- t7 y& H+ Q8 Z; R" S$ R7 Y# S

% [; R8 j1 S" j+ j9 o; C  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
+ l& @, _8 }* I( x2 c  set acceleration 0.099
! h! t& P4 I* ]  k; z7 r7 i4 [end
# U; D5 m, l/ P, g, t: z' ]" ~0 V5 v3 R9 k6 S  K+ e+ m
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,1 b) F& b' Z5 G# l* |
;; and initialize the traffic lights to one setting
3 C. `" |1 p  _* Y+ s$ Qto setup-patches
  _; t" r* _# y4 g3 ~' T  ;; initialize the patch-owned variables and color the patches to a base-color
  _8 L) l/ }* [4 G  l% z4 O  ask patches7 L) b" A3 d3 \1 d8 l
  [# u3 o. x* k' }: q1 d5 K% R
    set intersection? false: b6 U4 A) e1 W! P/ Y( t, T+ g% c1 j
    set auto? false1 h& I; T& w0 |
    set green-light-up? true
# x! y2 x6 Y# t/ S2 B- T' p# n5 F    set my-row -1
5 L7 ?' E- b2 @( g9 {( [4 R# J    set my-column -1( M" E( `" }- G( x( g
    set my-phase -1
0 g" @# m: A3 T: {; Z. A$ @  k    set pcolor brown + 38 X3 H1 p% d" Y/ n' t7 A
  ]
0 H/ t' c) j3 k. N6 b& u3 ?8 E( O$ j) u
  ;; initialize the global variables that hold patch agentsets1 ~! O3 P' A" D- [2 X
  set roads patches with+ t! G) Q1 O5 }* f- V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 m* W5 Z" {6 }2 V! ]6 h
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 {* T6 t# E  o: z4 {  set intersections roads with9 r( n5 X* `& V& P
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
2 p4 S+ H6 H* t$ l' V. k( f    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 f1 j% w- t4 j# Z/ x# ^' n+ E; l7 p( V, Q4 ~1 f& [6 `
  ask roads [ set pcolor white ]
  n1 L( H: X8 |    setup-intersections+ `  Y2 u/ t, s2 I1 O$ s- y0 j8 F4 }
end  ]' l+ V7 K) `
其中定义道路的句子,如下所示,是什么意思啊?
+ f; i7 A/ }" d7 \0 m8 x set roads patches with
. X9 o4 z' l( o    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 P* e( W& d! e    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 N4 F: r* _" F5 g. a$ A" E# J' 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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