Data Extraction

Select Objects by Property

Given an object list:

obj: [
 ["grid","","",-1.5,6.5,-2.5,4,40],
 ["forceGen","F_2",[-0.5,3.5]],
 ["momentGen","M_2",[1.5,3.5]],
 ["beam","",[0,0],[3,0],0.15,"locked"],
 ["bar","",[3,0],[5,-1],"hide"],
 ["fix12","A",[0,0],0,"hide"],
 ["fix12","C",[5,-1],0,"show"],
 ["label","\\(B\\)",[2.8,-0.5]],
 ["q","","q_0",[0,0.3],[3,0.3],0.7,0.7,0,"show"],
 ["force","A_v",[0,0],[0,1.6],10,"active"],
 ["force","A_h",[0,0],[1.1,0],10,"active"],
 ["force","B",[3,0],[4.2,-0.6000000000000001],10,"active"]
];

and the associated names

names: [0,0,0,"locked",[12],[10,11],"show",0,"show",A_v,A_h,B];

We want to extract entries by properties:

All forces:

sublist_indices (objects, lambda ([x], x[1]="force")); results in: [10,11,12]

All active forces

sublist (objects, lambda ([x], x[length(x)]="active" and x[1]="force")); results in [10,11,12]

Force B

sublist_indices (objects, lambda ([x], x[1]="force" and x[2]="B"));

Number of forces at object with given index

num: length( sublist_indices (names[index], lambda ([x], obj[x][1]="force" ) ) );

Indices of forces at fixed support A

names[sublist_indices (objects, lambda ([x], x[1]="fix12" and x[2]="A"))[1]]; results in [10,11]

active vertical force with name A_v

sublist_indices (objects, lambda ([x], x[length(x)]="active" and x[1]="force" and (x[4]-x[3])[1]=0 and x[2]="A_v")); results in [10]

Property Functions

Parallel Objects

a and b are items from the object list with 2-point based location (force, bar, spring, dashpot, but not rope).

parallelp(a,b):= block([da,db], 
  da: a[4]-a[3], db: b[4]-b[3],
  return(is (abs(da[1]*db[2]-da[2]*db[1])<0.05) ));