Buffer/Queue Cell

[stwirth]

In many applications some sensor input has to be buffered for further processing, i.e. an algorithm needs not only the current but also N past sensor values for processing. An example would be a median/mean/etc. filter of a fixed width.
Is there some functionality in ecto for that? If not, I am willing to write a cell that does that:
Input: any type
Params: number of values to buffer
Output: N outputs of same type as input, dependent on the number of values given as param.
This cell would gather N inputs before writing anything to the output. The output could be a vector as well, what do you suggest?

[straszheim]

Maybe just construct a cell that outputs a circular buffer of type T. You'd
need to instantiate it for your T. As I recall there is a circular buffer
in boost somewhere. A circular buffer of tendrils would be possible but a
hassle to work with if you cared what was in them...
On May 25, 2012 1:57 PM, "Stephan" <
[email protected]>
wrote:

In many applications some sensor input has to be buffered for further
processing, i.e. an algorithm needs not only the current but also N past
sensor values for processing. An example would be a median/mean/etc. filter
of a fixed width.
Is there some functionality in ecto for that? If not, I am willing to
write a cell that does that:
Input: any type
Params: number of values to buffer
Output: N outputs of same type as input, dependent on the number of values
given as param.
This cell would gather N inputs before writing anything to the output. The
output could be a vector as well, what do you suggest?

---

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#204

[straszheim]

Hm, or a std::deque.
On May 25, 2012 3:52 PM, "Troy Straszheim" [email protected]
wrote:

Maybe just construct a cell that outputs a circular buffer of type T.
You'd need to instantiate it for your T. As I recall there is a circular
buffer in boost somewhere. A circular buffer of tendrils would be possible
but a hassle to work with if you cared what was in them...
On May 25, 2012 1:57 PM, "Stephan" <
[email protected]>
wrote:

In many applications some sensor input has to be buffered for further
processing, i.e. an algorithm needs not only the current but also N past
sensor values for processing. An example would be a median/mean/etc. filter
of a fixed width.
Is there some functionality in ecto for that? If not, I am willing to
write a cell that does that:
Input: any type
Params: number of values to buffer
Output: N outputs of same type as input, dependent on the number of
values given as param.
This cell would gather N inputs before writing anything to the output.
The output could be a vector as well, what do you suggest?

---

Reply to this email directly or view it on GitHub:
#204

[stwirth]

If i just want to pass a "delayed" value, not the whole buffer: is it possible to write the cell independent of the type of input/output? Just like the passthrough cell but with a buffer in between.

[straszheim]

Sure, deque of tendrils ought to do it

On Fri, May 25, 2012 at 5:02 PM, Stephan <
[email protected]

wrote:

If i just want to pass a "delayed" value, not the whole buffer: is it
possible to write the cell independent of the type of input/output? Just
like the passthrough cell but with a buffer in between.

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#204 (comment)

Troy Straszheim
Cofounder, CEO
Industrial Perception, Inc.

[stwirth]

Could you please have a look at my implementation and tell me what's wrong?
https://github.com/stwirth/ecto/compare/delay_cell
The second test of test_delay.py does not work as expected, the output of the adder is always 0.

[straszheim]

On Fri, May 25, 2012 at 5:58 PM, Stephan <
[email protected]

wrote:

Could you please have a look at my implementation and tell me what's wrong?
https://github.com/stwirth/ecto/compare/delay_cell
The second test of test_delay.py does not work as expected, the output of
the adder is always 0.

---

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#204 (comment)

It looks like the ecto bits are correct. You might use std::deque and
push_front/pop_back to be sure you're using the datastructure the right
way. Print its contents and all that.

Troy Straszheim
Cofounder, CEO
Industrial Perception, Inc.

[stwirth]

Thanks! I forgot to return ecto::OK. What is the right way to return from process() when the outputs are not touched? return ecto::BREAK, return ecto::CONTINUE? When I always return ecto::OK, the first N outputs of my Delay cell are None values which the subsequent cells (like Add) do not like. I thought process would not be called on cells whose inputs are not set.

[vrabaud]

Well, that makes sense but we usually just deal with that by stacking
things into member variables.
(cf
https://github.com/wg-perception/tod/blob/master/src/training/ModelStacker.cpp
)

If you feel like writing a cell, please ! Maybe it should take a vector or
N outputs ? (or list maybe to make it more efficient)

On Fri, May 25, 2012 at 6:57 AM, Stephan <
[email protected]

wrote:

In many applications some sensor input has to be buffered for further
processing, i.e. an algorithm needs not only the current but also N past
sensor values for processing. An example would be a median/mean/etc. filter
of a fixed width.
Is there some functionality in ecto for that? If not, I am willing to
write a cell that does that:
Input: any type
Params: number of values to buffer
Output: N outputs of same type as input, dependent on the number of values
given as param.
This cell would gather N inputs before writing anything to the output. The
output could be a vector as well, what do you suggest?

---

Reply to this email directly or view it on GitHub:
#204