Logical Vectors to make find max, mean, and min

Hello,

I need to manipulate the Temp array (via logical vectors) to make vectors of max, mean, and min temperatures on each day of the data set. However, I keep getting the error message: Improper assignment with rectangular empty matrix. Error in (line 54) temp_max(i) = max(New_Temp(lv2)); Any help is greatly appreciated! My code is below.

 clear
 clc

 %Number of lines of data
    N = 2902;
 %Number of lines before data values start
    hdr = 22;
 %Adjust to read past 500 limit
    set(0,'Recursionlimit',N);

 Time = [ ]; Temp = [ ]; Pres = [ ]; Lite = [ ];

 for n = 1:14
     if 1i <= 9 
         filename = ['Weather_Data_13-10-0' num2str(1i) '_1042.lvm'];
     else
         filename = ['Weather_Data_13-10-' num2str(1i) '_1042.lvm'];
     end
     [a, b, c, d] = textread('data.txt', '%f%f%f%f', N,'headerlines',hdr);
 end

 Time = [Time; a]; 
 Temp = [Temp; b]; 
 Pres = [Pres; c]; 
 Lite = [Lite; d]; 

 %Normalize Time from hours to days
 Time = (Time*3600)/86400;
 %Normalize time on first day to first data point (= zero)
 Time = Time - Time(1);
 shift = ((10 + (42/60) + (13.4/3600)))*3600/86400;
 Time = Time + shift;

 %Save Variables to new .mat file
 save('WeatherData_Oct13.mat', 'Time', 'Temp', 'Pres', 'Lite')

 clear

 %Part 2:
 load('WeatherData_Oct13.mat')

 %Manipulate the temp array (via logical vectors, etc.) to make vectors of max, 
 %mean and min temperatures on each day of the data set.
 lv1 = (Time > 1 & Time < 14);
 New_Temp = Temp(lv1);
 New_Time = Time(lv1);

 temp_max = [];
 temp_mean = []; 
 temp_min = [];

 for i = 1:14
    lv2 = (New_Time > i & New_Time < i+1);
    temp_max(i) = max(New_Temp(lv2));
    temp_mean(i) = mean(New_Temp(lv2));
    temp_min(i) = min(New_Temp(lv2));
 end

[Image Analyst]

You forgot to attach your data files. No one can run your code unless you supply your data file. I've attached your original question so that when you delete it like you did your other question, it will still be here.

Answer 1

[Walter Roberson]

temp_max(i) = max(New_Temp(lv2)); would error with that message if lv2 selected no elements out of New_Temp, leaving nothing to be max()'d. You cannot assign the empty element into a numeric location.