How to make a simple plot with two lines?

Hi. I am new to MatLab. I want to make a plot with two lines for 2001 and 2003 group of schoolyear vs students. (Please note, not "year", but "schoolyear"). The x-axis would have the 12 months of the year, and the y-axis has the students.

table_a = readtable('Data1.xlsx');

for i = 1:height(table_a)
if table_a.month(i)>=8
    schoolyear(i) = table_a.year(i) + 1;
else
    schoolyear(i) = table_a.year(i);
end
end
table_a.schoolyear = schoolyear(:)

table_a = 48×4 table
    month    year    students    schoolyear
    _____    ____    ________    __________

      1      2000       12          2000   
      2      2000       14          2000   
      3      2000       13          2000   
      4      2000       11          2000   
      5      2000       17          2000   
      6      2000       14          2000   
      7      2000       10          2000   
      8      2000        9          2001   
      9      2000       16          2001   
     10      2000       11          2001   
     11      2000        4          2001   
     12      2000        6          2001   
      1      2001        5          2001   
      2      2001        7          2001   
      3      2001        8          2001   
      4      2001        9          2001   

% how do I make a single plot with two lines, one for 2001 and one for
% 2003. It would be a time series, the month would be on the x-axis, and
% students would be on the y-axis.

Answer 1

[Paul]

Hi Macy,

%table_a = readtable('Data1.xlsx');
table_a = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/1289895/Data1.xlsx');

for i = 1:height(table_a)
if table_a.month(i)>=8
    schoolyear(i) = table_a.year(i) + 1;
else
    schoolyear(i) = table_a.year(i);
end
end
table_a.schoolyear = schoolyear(:)

table_a = 48×4 table
    month    year    students    schoolyear
    _____    ____    ________    __________

      1      2000       12          2000   
      2      2000       14          2000   
      3      2000       13          2000   
      4      2000       11          2000   
      5      2000       17          2000   
      6      2000       14          2000   
      7      2000       10          2000   
      8      2000        9          2001   
      9      2000       16          2001   
     10      2000       11          2001   
     11      2000        4          2001   
     12      2000        6          2001   
      1      2001        5          2001   
      2      2001        7          2001   
      3      2001        8          2001   
      4      2001        9          2001   

Logical indices for the desired school years.

index2001 = table_a.schoolyear == 2001;
index2003 = table_a.schoolyear == 2003;

Extract the corresponding months and students.

month2001 = table_a.month(index2001); students2001 = table_a.students(index2001);
month2003 = table_a.month(index2003); students2003 = table_a.students(index2003);

Sort by month in ascending order (I assumed this is what you want). Reorder corresponding students.

[month2001,index2001] = sort(month2001); students2001 = students2001(index2001);
[month2003,index2003] = sort(month2003); students2003 = students2003(index2003);

Plot

plot(month2001,students2001,'-o',month2003,students2003,'-o');
xlabel('month'),ylabel('students')
legend('2001','2003')

Answer 2

[Venkat Siddarth]

Hi @Macy,

I understand that you are trying to plot two lines in a single axis with x-axis as months and y-axis as corresponding students in the respective years. This can be achieved as follows:

%Firstly,load the data and add the "schoolyear" column 
table_a = readtable('Data1.xlsx');

for i = 1:height(table_a)
if table_a.month(i)>=8
    schoolyear(i) = table_a.year(i) + 1;
else
    schoolyear(i) = table_a.year(i);
end
end
table_a.schoolyear = schoolyear(:)

After that we will obtain the data in the form of vector using curly brackets({})

%obtaining and sorting months and corresponding students data with schoolyear 2001
data_2001=sortrows(table_a{table_a{:,"schoolyear"}==2001,["month" "students"]},1);
%obtaining and sorting months and corresponding students data with schoolyear 2003
data_2003=sortrows(table_a{table_a{:,"schoolyear"}==2003,["month" "students"]},1);

After that we plot the data using plot function and using the command hold on we create the plots on same axis.

plot(data_2001(:,1),data_2001(:,2),"s-");
hold on
plot(data_2003(:,1),data_2003(:,2),"o-");
legend(["2001" "2003"])
hold off

I hope this resolves your query.

Thanks,

Venkat Siddarth V

Answer 3

[Macy]

@Paul thank you, this saved me a lot of time as I was trying to do it using a for loop.