No more plot although no errors

Question

Peter Groh 2017-9-28

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/358785-no-more-plot-although-no-errors

回答： Christopher Stapels 2017-12-14

My Visualizations stopped displaying anything ( no plot) - it worked for months. Even taking the template "Create a 2-D line plot" I just get the the result " _ MATLAB code ran successfully_." and no error code in the output field - but still no plot.

Is there a problem with connecting to thingspeak or what has changed?

.

Here the simple code from the template:

% Template MATLAB code for visualizing data from a channel as a 2D line
% plot using THINGSPEAKPLOT function.
% Prior to running this MATLAB code template, assign the channel ID to read
% data from to the 'readChannelID' variable. Also, assign the field ID
% within the channel that you want to read data from to plot. 
% TODO - Replace the [] with channel ID to read data from:
readChannelID = [139311];
% TODO - Replace the [] with the Field ID to read data from:
fieldID1 = [5];
% Channel Read API Key 
% If your channel is private, then enter the read API
% Key between the '' below: 
readAPIKey = '';
%%Read Data %%
[data, time] = thingSpeakRead(readChannelID, 'Field', fieldID1, 'NumPoints', 30, 'ReadKey', readAPIKey);
%%Visualize Data %%
thingSpeakPlot(time, data);

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Rik 2017-9-28

Are data and time empty? The reason for the absence of a plot can most likely be found inside either thingSpeakRead or thingSpeakPlot.

Have a read here and here. It will greatly improve your chances of getting an answer.

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Answer 1

Christopher Stapels 2017-12-14

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/358785-no-more-plot-although-no-errors#answer_296245

As of December 14, your channel has recent values in it. I think the NaN values between real values are making the plot scale unexpectedly. Try adding a LineSpec For example, plot(timeA,dataA,'ro-');