Make a plot only with recent data

[vik748]

Hi, I am trying to use multiplot to plot odom x vs odom y (which I have converted from lat/long to UTM). In the plot I want to be able to see the most recent point (or points). I tried to accomplish this by adding 2 curves, one with the data being a vector and a 2nd curve for the recent points. For the 2nd curve I have tried using circular buffer with low capacities and time frames of 1-5 secs. In the plot I can get the desired behavior for a few secs after which the 2nd plot keeps the full track. If I clear the plots I can get the behavior for a few secs again. Is this the correct way of achieving the desired behavior or is there a better way?

[samuelba]

Hi @vik748 This behavior should be achievable with the circular buffer you mentioned. "Time frame" doesn't work in your case, since you would have to plot a timestamp on the x-axis.

[vik748]

@samuelba I was able to achieve it, but as I mentioned earlier it works for a few secs and then breaks. After a few secs the “circular buffer” plot starts tracking the whole data set.

[ckurtz22]

Similar to @vik748 , when I try to use circular data it just does not seem to work at all on Melodic. Maybe I am understanding it wrong, but I would expect that if I have the circular data buffer set to 10, then after 10 points are added to the graph (i.e. 10 messages on the topic), then the graph will start overwriting the beginning points?

Ideally for me I would like to be able to have it so if a data point with an identical X value to a previous data point is received, it removes the previous point and replaces it with the new point

[henryliuliuliu]

how can use it like the rqt_plot, if i want to subscribe some topics and draw its data?