cart

Short for Cartesian, the cart() gear combines data from its inputs, at least one of which is of the Queue type. It combines each element of the data received at its second input with whole data value received at its first input.

cart(*din)

Most often the cart() gear is used to combine a Queue and some other non-Queue data, so that the non-Queue data is replicated for each element of the Queue.

Imagine if we have a Queue of x coordinates [10, 11, 12], and we would like to attach to each of them an y coordinate to form a point. The y coordinate is generated by a source which does not know how long our Queue -s are so it only outputs a single value 0, which is than replicated by the cart() gear for each element of the Queue carrying the x coordinate. The result of the cart() operation is a Queue of points [(10, 0), (11, 0), (12, 0)]. Observe how the value 0, received at din1 input of the cart() gear is acknowledged only after it has been combined with all the elements of the Queue (in the third cycle).

x = drv(t=Queue[Uint[5]], seq=[[10, 11, 12]])
y = drv(t=Uint[5], seq=[0])

cart(x, y) | check(ref=[[(10, 0), (11, 0), (12, 0)]])

Next example has identical data types as the previous one, only its driving sequence is longer.

op1 = drv(t=Queue[Uint[5]], seq=[[10, 11, 12], [20, 21, 22]])
op2 = drv(t=Uint[1], seq=[0, 1])

cart(op1, op2) | check(ref=[[(10, 0), (11, 0), (12, 0)], [(20, 1), (21, 1), (22, 1)]])

Finally, this example shows how two Queue -s are combined using the cart gear.

op1 = drv(t=Queue[Uint[5]], seq=[[10, 11], [20, 21], [30, 31]])
op2 = drv(t=Queue[Uint[5]], seq=[[10, 11, 12]])

cart(op1, op2) | check(ref=[[[(10, 10), (11, 10)], [(20, 11), (21, 11)], [(30, 12), (31, 12)]]])

cart_sync(*din)

Performs the same operation as the cart() gear regarding the data replication, however it does not combine the data at the output, but outputs each of the data via separate interface.

op1 = drv(t=Queue[Uint[5]], seq=[[10, 11, 12], [20, 21, 22]])
op2 = drv(t=Uint[1], seq=[0, 1])

out1, out2 = cart_sync(op1, op2)
out1 | check(ref=[[10, 11, 12], [20, 21, 22]])
out2 | check(ref=[0, 0, 0, 1, 1, 1])

cart_sync_with(sync_in, din) → din

Performs the same operation as the cart() gear regarding the data replication, however it does not combine the data at the output, but outputs only the interface whose data has been replicated. Useful if we don’t need the data combination, just the replication.

sync = drv(t=Queue[Uint[5]], seq=[[10, 11, 12], [20, 21, 22]])

drv(t=Uint[1], seq=[0, 1]) \
    | cart_sync_with(sync) \
    | check(ref=[0, 0, 0, 1, 1, 1])