Plot a 2D graph from a csv file using matplotlib in Python in ubuntu

Firstly, we should escape out the spaces in the path to make certain that it isn't choking on that:

cv,dv = np.loadtxt('/home/kishore/Documents/Owlstone\ developer\ task\ briefing/test_matrix.csv',delimiter=',',unpack=True)

or, change your directory name to have no spaces, e.g. Owlstone.

Alternatively, you could move the file and the script into the same directory and remove all the path information to prove that all is well with actually finding the file n the first place. It is clear from your error output that you are not getting past this line, so concentrate there first.

Now past the escaped space potential, let's concentrate on what is in the file. Your image and your posted data are not using , as a delimiter. Fixing that and using as data

-7.49952,7.6904296,7.64923087,7.81402579,7.59429923,7.73162833
-7.48388,7.56683341,7.51190177,7.38830558,7.67669669,7.38830558
-7.46824,7.03124992,7.38830558,7.49816886,7.51190177,7.66296378
-7.4526,7.53936759,7.66296378,7.71789542,7.62176505,7.6904296
-7.43696,7.49816886,7.73162833,7.45697013,7.71789542,7.38830558
-7.42132,7.01751701,7.20977775,7.48443595,7.58056632,7.81402579
-7.40568,7.58056632,7.71789542,7.70416251,7.49816886,7.58056632

where I have removed the first row (rather than skiprows=1 as suggested above, since that doesn't fix the Too many values to unpack problem) I can get an array via

dv = np.loadtxt('text.csv', delimiter=',')
print(dv)

yielding

[[-7.49952     7.6904296   7.64923087  7.81402579  7.59429923  7.73162833]
 [-7.48388     7.56683341  7.51190177  7.38830558  7.67669669  7.38830558]
 [-7.46824     7.03124992  7.38830558  7.49816886  7.51190177  7.66296378]
 [-7.4526      7.53936759  7.66296378  7.71789542  7.62176505  7.6904296 ]
 [-7.43696     7.49816886  7.73162833  7.45697013  7.71789542  7.38830558]
 [-7.42132     7.01751701  7.20977775  7.48443595  7.58056632  7.81402579]
 [-7.40568     7.58056632  7.71789542  7.70416251  7.49816886  7.58056632]]

N.B.: You can prove that things are working in general by including the following either in the console or in your code:

from StringIO import StringIO
c = StringIO("-7.49952,7.6904296,7.64923087,7.81402579,7.59429923,7.73162833\n-7.48388,7.56683341,7.51190177,7.38830558,7.67669669,7.38830558")
print(np.loadtxt(c, delimiter=","))

and you will see a nice array as well.

Now to plot we are going to work with the data presented, and we have (X,Y) pairs of the form (col2, col1) for the matrix, so the first two values to be plotted are (7.6904296, -7.49952) and (7.56683341, -7.48388) and we are disregarding the remainder of each row, columns 3-6, originally labelled as 2,3,4,5.

def graph():
    dv = np.loadtxt('text.csv', delimiter=',')
    print(dv)
    fig = plt.figure()
    ax = fig.add_subplot(1, 1, 1)
    x = dv[:,1]
    y = dv[:,0]
    ax.scatter(x,y)
    plt.title('Chemical Presence')
    plt.ylabel('CV')
    plt.xlabel('DV')
    plt.show()

The notation here of dv[:,0] is subsetting the array dv with all the rows and only the values of column 0, with the general format being array[rows,columns]. This code gives us