hello every one i want to ask that how can i plot a moving graph using qwt as i am new to qwt so i dont have any idea
like i want a curve. my data is continuously coming. that is i want two adjacent points to gradually join by curved line hope you people understands what i am trying to say
is there any way to do this
kindly help me i will be very thank full to you people
Create a timer with 50ms period (25Hz frequency) and update the plot data on timers timeout signal.
EDIT: I looked at the QwtPlot closer. I assume that you use it with QwtPlotCurve. I think you can use its SetRawData method and every 50 miliseconds (or longer, depends on what you need) update your data arrays, then replot your graph with the replot method. Don't know if you have to invoke SetRawData on every update, according to Set Data description, you don't.
Or you can use AutoReplot. If you enable it with QwtPlot::setAutoReplot, invoking QwtPlotCurve::SetData with new data set should replot it automatically.
Related
I have asked a few questions related to this personal project of mine already on this platform, and this should be the last one since I am so close to finishing. Below is the link to a mock example spreadsheet I've created, which mimics what my actual project does but it contains less sensitive information and is also smaller in size.
Mock Spreadsheet
Basic rundown of the spreadsheet:
Pulls data from a master schedule which is controlled/edited by another party into the Master Schedule tab.
In the columns adjacent to the imported data, an array formula expands the master schedule by classroom in case some of the time slots designate multiple rooms. Additional formulas adjust the date, start time, and end time to be capped within the current day's 24-hour period. The start time of each class is also made to be an hour earlier.
In the Room Schedule tab, an hourly calendar is created based on the room number in the first column, and only corresponds to the current day.
I have tested the spreadsheet extensively with multiple scenarios, and I'm happy with how everything works except for the calculation time. I figured the two volatile functions I use would take some processing time just by themselves, and I certainly didn't expect this to be lightning-fast especially without using a script, but the project that I am actually implementing this method for is much larger and takes a very long time to update. The purpose of this spreadsheet is to allow users to find an open room and "reserve" it by clicking the checkbox next to it (which will consequently color the entire row red) allowing everyone else to know that it is now taken.
I'd like to know if there is any way to optimize / speed up my spreadsheet, or to not update it every time a checkbox is clicked and instead update it "manually", similar to what OP is asking here. I am not familiar with Apps Script nor am I well-versed in writing code overall, but I am willing to learn - I just need a push in the right direction since I am going into this blind. I know the number of formulas in the Room Schedule tab is probably working against me yet I am so close to what I wanted the final product to be, so any help or insight is greatly appreciated!
Feel free to ask any questions if I didn't explain this well enough.
to speed up things you should avoid usage of the same formulae per each row and make use of arrayformulas. for example:
=IF(AND(TEXT(K3,"m/d")<>$A$1,(M3-L3)<0),K3+1,K3+0)
=ARRAYFORMULA(IF(K3:K<>"",
IF((TEXT(K3:K, "m/d")<>$A$1)*((M3:M-L3:L)<0), K3:K+1, K3:K+0), ))
=IF(AND(TEXT(K3,"m/d")=$A$1,(M3-L3)<0),TIMEVALUE("11:59:59 PM"),M3+0)
=ARRAYFORMULA(IF(K3:K<>"",
IF((TEXT(K3,"m/d")=$A$1)*((M3-L3)<0), TIMEVALUE("11:59:59 PM"), M3:M+0), ))
Using the QCustomPlot add on for QT. I am having to plot points which may are not linear so the graph could look something like this
how ever this is the result
but this is what shows up
using this code
plotter->addGraph();
plotter->graph(0)->setData(xVector, yVector);
plotter->xAxis->setLabel("X");
plotter->yAxis->setLabel("Y");
plotter->xAxis->setRange(x_data_range_min x_data_range_max);
plotter->yAxis->setRange(y_data_range_min, y_data_range_max);
plotter->replot();
plotter->saveJpg("test.jpg");
plotter->close();
now I found a partial fix, by adding this option to get ride of the connected lines and only show the points,
plotter->graph(0)->setLineStyle((QCPGraph::LineStyle)QCPGraph::lsNone);
plotter->graph()->setScatterStyle(QCPScatterStyle(QCPScatterStyle::ssDisc , 3));
and the result is this but has a problem, it leaves a kinda bold spot which I can't have
so this is a semi-solution. So I went ahead and added what A. Sarid mentioned in the replys below. I think the first graph may plot fine, but any other graph after it looks like this
so I am not sure which solution can make only the dots connect in the order in which they are received from the array
I just had the same problem few days ago.
You need to use QCPCurve Class instead of Graph. Here is a small example of how to do it:
this->newCurve = new QCPCurve(ui->customPlot->xAxis, ui->customPlot->yAxis);
ui->customPlot->addPlottable(this->newCurve);
And then you can use it the same way you use graph, for example:
this->newCurve->setData(x, y);
I'm a little confused about online kmeans clustering. I know that it allows me to cluster with just one data at a time. But,is this all limited to one session? Suppose that I have a bunch of data clustered via this method and I get the clustered data result, would I be able to add more data to the cluster in the future?
I've also been looking for implementations of this code, and to no avail. Anyone know of any?
Update:
To clarify more. Here is how my code works right now:
Image is taken from live video feed, once enough pictures are saved, get kmeans of sift features.
Repeat step 1, a new batch of live feed pictures, get kmeans again. Combine the kmeans vectors with the previous kmeans like :[A B]
You can see that this is bad, because I quickly get too much clusters, and each batch of clusters will definitely have overlaps with another batch.
What I want:
Image taken from live video feed, once pics are saved, get kmeans
Repeat step 1, get kmeans again, which updates and adds new clusters to the previous cluster.
Nothing that I've seen could accommodate that, unless I'm just not understanding them correctly.
If you look at the original (!) publications, the method proposed by MacQueen - where the name k-means comes from - was in fact an online algorithm. I'm not sure if MacQueen did multiple passes over the data to improve the result. I believe he used a single pass, and objects would never be reassigned to a different cluster. If so, it was already an online algorithm!
Means are commonly computed as sum / count. This is not very sensible from a numerical point of view. E.g. in the classic Knuth book you can find a method for incrementally updating means. Wikipedia has it also.
Things get slightly more complicated once you actually want to reassign earlier points. But usually in a streaming context you do not know the previous points, so you cannot do that anyway.
I've seen some similar questions out of which I have made a system which works for me but I need to optimize it because this program alone is taking up a lot of CPU load.
Here is the problem exactly.
I have an incoming signal/stream of data which I need to plot in real time. I only want a limited number of points to be displayed at a time (Say 1024 points) so I plot the data points along the y axis against an index from 0-1024 on the x-axis. The values of the incoming data range from 0-1023.
What I do currently (This is all in C++) is I put the data into a circular loop as it comes and each time the data gets updated (Or every second/third data point), I write out to a file and using a pipe, I plot the data from that file with gnuplot.
While this works almost perfectly, it causes a fair bit of load (Depending on the input data rate, I saw even 70% usage on both my cores of my Core 2 Duo). I'll need to be running some processor intensive code along with this short program so I feel that it is almost necessary to optimize it.
What I was hoping could be done is this: Can I only plot the differences between the current plot and the new data (Or plot each point as it comes in without replotting the whole graph such that the old item at that x index is removed).
I have a fixed number of points on the graph so replot wouldn't work. I want the old point at that x location to be removed.
Unfortunately, what you're trying to accomplish can't be done. You can mark a datafile as volatile or use the refresh keyword, but those only update the plot without re-reading the data. You want to re-read the data and then only update the differences.
There are a few things that might be helpful though. 1) your eye can only register ~26 frames per second. So, if you have a way to make sure that you only send data 26x per second to gnuplot, that might help. 2) How are you writing the datafiles? Are you dumping as ascii or binary? Doing a binary dump might be faster (both for writing and for gnuplot to read). You'll have to experiment.
There is one hack which will probably not make your script go faster, but you can try it (if you know a reasonable yrange to set, and are using points to plot the data)...
#set up code:
set style line 1 lc rgb "blue"
set xrange [0:1023]
set yrange [0:1]
plot NaN notitle #Only need to do this once.
for [i=0:1023] set label i+1 at i,0 point ls 1 #Labels must have tags > 0 :-(
#this part gets repeated by your C code.
#you could move a few points at a time to make it more responsive.
set label 401 at 400,0.8 #move point number 400 to a different y value
refresh #show it at it's new location.
You can use gnuplot to do dynamic plotting of data as explained in their FAQ, using the reread function. It seems to run at quite a low load and automatically scrolls the graph when it reaches the end. To run at low load I found I had to add a ; sleep 1 after the awk command (in their example file dyn-ping-loop.gp) otherwise it spends too much CPU on looping on the awk processing.
I'm going to write a program that plots data from a sensor connected to the computer. The sensor value is going to be plotted as a function of the time (sensor value on the y-axis, time on the x-axis). I want to be able to add new values to the plot in real time. What would be best to do this with in C++?
Edit: And by the way, the program will be running on a Linux machine
Are you particularly concerned about the C++ aspect? I've done 10Hz or so rate data without breaking a sweat by putting gnuplot into a read/plot/refresh loop or with LiveGraph with no issues.
Write a function that can plot a std::deque in a way you like, then .push_back() values from the sensor onto the queue as they come available, and .pop_front() values from the queue if it becomes too long for nice plotting.
The exact nature of your plotting function depends on your platform, needs, sense of esthetics, etc.
You can use ring buffers. In such buffer you have read position and write position. This way one thread can write to buffer and other read and plot a graph. For efficiency you usually end up writing your own framework.
Size of such buffer can be estimated using eg.: data delivery speed from sensor (40KHz?), size of one probe and time span you would like to keep for plotting purposes.
It also depends whether you would like to store such data uncompressed, store rendered plot - all for further offline analysis. In non-RTOS environment your "real-time" depends on processing speed: how fast you can retrieve/store/process and plot data. Usually it is near-real time efficiency.
You might want to check out RRDtool to see whether it meets your requirements.
RRDtool is a high performance data logging and graphing system for time series data.
I did a similar thing for a device that had a permeability sensor attached via RS232.
package bytes received from sensor into packets
use a collection (mainly a list) to store them
prevent the collection to go over a fixed size by trashing least recent values before new ones arrive
find a suitable graphics library to draw with (maybe SDL if you wanna keep it easy and cross-platform), but this choice depends on what kind of graph you need (ncurses may be enough)
last but not least: since you are using a sensor I suppose your approach will be multi-threaded so think about it and use a synchronized collection or a collection that allows adding values when other threads are retrieving them (so forgot iterators, maybe an array is enough)
Btw I think there are so many libraries, just search for them:
first
second
...
I assume that you will deploy this application on a RTOS. But, what will be the data rate and what are real-time requirements! Therefore, as written above, a simple solution may be more than enough. But, if you have hard-real time constraints everything changes drastically. A multi-threaded design with data pipes may solve your real-time problems.