Error scatter plot time vs wind speed (data from a table)

I am trying to make a simple scatter plot with time on the x-axis and wind speed on the y-axis. I loaded in my data from a txt file as a table and then tried to use table2array to plot since it needs numeric values not table data. I also tried using double and got another error.

Error Message: Error using scatter (line 55) Input arguments must be numeric or objects which can be converted to double.

Error in windconversions (line 18) scatter(time,wnd_TS)

T = readtable('allunderway.txt', 'HeaderLines', 2);
%A = table2array(T)

date = T(:,1);
time = T(:,2);
wnd_TD = T(:,10);
wnd_TS = T(:,11);
table2array(wnd_TS);
table2array(time);
%double(wnd_TS);
scatter(time,wnd_TS)

[Paolo]

Could you attach the .txt file to your question?

[Marissa Menzel]

Done!

Answer 1

[Greg]

You're misunderstanding how MATLAB operates. Functions like table2array don't manipulate the variable in place, they return it as an explicit output variable. Replace

table2array(wnd_TS);
table2array(time);

with

wnd_TS = table2array(wnd_TS);
time = table2array(time);

Better than that though is to index into tables properly:

scatter(T.Time_GMT,T.Wnd_TS);

[Marissa Menzel]

I tried the new scatter line and got an error Error using windconversions (line 20) Unrecognized variable name 'time'.

[Greg]

Sorry, I was looking at your time = T(:,2) line rather than the data file. See updated answer.