Unable to Plot in For Loop

I am trying to make a two y-axis plot in a for loop using the code below:

t = 10;
for n = 1:t
  TempFile = sprintf('%s%d', 'ShearEnv_top', n);
  m = hour(TempFile(:,5));
  plot(m, TempFile(:,12) .* 10, 'b-'), ylim([0 360]), grid minor, ylabel('Wind Direction (degrees)'), xlabel('Time of Day(Hr)'), title('Daily Wind Direction Patterns');

    yyaxis right, plot(m, TempFile(:,14) ./ 3.6, 'g-')
  end

However when I run it I get the error;

"Error using plot
Invalid first data argument.

Error in Keep_3 (line 8)
    plot(TempFile(:,5), TempFile(:,12) .* 10, 'b-'), ylim([0 360]), grid minor, ylabel('Wind Direction (degrees)'), xlabel('Time of Day(Hr)'), title('Daily Wind Direction Patterns');'

I`ve tried using the hour function but I either get an error when using brace brackets for;

Or an error that the input is of type 'char'

t = 10;
for n = 1:t
  TempFile = sprintf('%s%d', 'ShearEnv_top', n);
  m = hour(TempFile(:,5));
  plot(m, TempFile(:,12) .* 10, 'b-')
  ylim([0 360]), grid minor
  ylabel('Wind Direction (degrees)'), xlabel('Time of Day(Hr)'), title('Daily Wind Direction Patterns');
  yyaxis right, plot(m, TempFile(:,14) ./ 3.6, 'g-')
end

"Undefined function 'hour' for input arguments of type 'char'.

Error in Keep_3 (line 8)
    m = hour(TempFile(:,5));"

I have made plots in Matlab R2017a with this code but in Matlab R2018a these errors arise.

[Viren Gupta]

I tried this in R2018a.

       TempFile(:,5) % value = 'r'.
      What does parsing 'r' in hour function mean?

Answer 1

[Steven Lord]

It looks like TempFile is the name of a file that you want to read into MATLAB, but you skipped the actual file reading step.

Alternately, it could be the name of a variable (one in a series of sequentially named variables) that you want to use, but if that's the case you shouldn't do that. Use the alternative approaches described on that page instead.