Databases
StackOverflow2013
Postsdbo
POgnuplot Real Time Plotting C Implementation
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POgnuplot Real Time Plotting C Implementation
    primarykey
    data
    text
    <p>I'm completely new to gnuplot and have only learned the basics to start plotting. I'm writing a C program that does DSP and needs to plot the result in real time. In addition, I've setup my program in such following manner to incorporate the plot '-' feature from gnuplot. The parent process will perform the DSP computation constantly, and sends the result to the child using pipe in real time. The child will receive a signal from parent, wake up, and sends the result to gnuplot via pipe.</p> <p>Basically, the path of data goes as such:</p> <p>Parent(Computation) -> Pipe -> Child (Wait on Input from parent) -> Pipe -> gnuplot (Plotting)</p> <p>For example, in the child, enclosed in a conditional wait</p> <pre><code>getline(&amp;lineBuffer, lineSize, stdin); printf("%s", lineBuffer); fflush(stdout); </code></pre> <p>where <code>lineBuffer</code> can be any arbitrary <code>char*</code>, will redirect data from parent to gnuplot. I have all the necessary data for plotting, and it can be formatted in any format. However, after trying the following, there has been no success. </p> <p>If not yet defined appearances and label,</p> <pre><code>set terminal x11 persist noraise set xlabel "Frequency" set ylabel "Decibel" set xrange [0:2000] set yrange [-100:100] set style data lines </code></pre> <p>Start initial plot command,</p> <pre><code>plot '-' using 1:2 smooth unique </code></pre> <p>Start sending data, each point is a new line, where I formatted my data to be</p> <pre><code>Frequency Decibel </code></pre> <p>at a particular time, for example</p> <pre><code>1000 -30.00 1001 -31.00 .... </code></pre> <p>End data by sending</p> <pre><code>e\n </code></pre> <p>Then I restart the process sending the data, and end it with </p> <pre><code>replot </code></pre> <p>Does this seem right? On the other hand, I'm also interested in plotting the time series of a particular frequency, and after numerous searches, apparently I need a buffer or a temporary file to accomplish this, is that correct also?</p>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USFan Jin
    1. USFan Jin
    plurals
    1. PL
      singulars
      1. LTLinked
    2. PL
      singulars
      1. LTLinked
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. COIf this information will be helpful, gnuplot stops earlier when the data size is larger.
      singulars
      1. POgnuplot Real Time Plotting C Implementation
      1. USFan Jin
    2. COThere is no real way to send incremental data to extend a plot in gnuplot. You always need to send all the data, which you want to plot. So, a way would be to write into a temporary file, which is reread by gnuplot, see the last script [in this answer](http://stackoverflow.com/a/18297966/2604213). I don't know exactly how you want to plot the time series of a certain frequency (how many data sets etc), but you cannot use `every` to select a certain frequency, because `every` applies to the original data and not to the computed frequencies. So yes, you propably need an external file for this.
      singulars
      1. POgnuplot Real Time Plotting C Implementation
      1. USChristoph
    3. CO@Christoph Could you please elaborate on what you mean by the ’original data‘ and the ’computed frequencies‘? I can format/organize the result in any manner I want. For example, if I try to plot manually, with the data file below.
      singulars
      1. POgnuplot Real Time Plotting C Implementation
      1. USFan Jin
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload