ValueError x and y must have same first dimension, but have shapes (4500,) and (4499,)

Question

#I have a dataframe for a growing polymerization reaction that looks like this:

d_result['M']=
array([70.        , 69.99738611, 69.98974828, ...,  0.02669216,
        0.02664559,  0.02659911])

Also ;

d_result['time']=
array([  0. ,   0.1,   0.2, ..., 449.7, 449.8, 449.9])
#I intend to produce a plot of 'X' against 'time' for the growing chain versus time;

X = (d_result['M'][0]-d_result['M'][-1])/d_result['M'][0]. # 'X',Monomer conversion
 

Obtaining the plot:

    d_trajectory = d_result
    plt.plot(d_trajectory['time'], ((d_trajectory['M'][0]-d_trajectory['M'][:-1])/d_trajectory['M'][0]), 'k')
    plt.xlabel('Time')
    plt.ylabel('Conversion,X')

   

#I got the following error: #ValueError: x and y must have the same first dimension, but have shapes (4500,) and (4499,)

Answer 1

d_trajectory['M'][:-1] doesn't include the last element of the array and is therefore shorter by 1 than d_trajectory['time'], see Understanding slice notation. Try d_trajectory['M'] or d_trajectory['M'][:].