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Learn more about Teams P = np.array(input('Please enter the P vector:\n')) Q = np.array(input('\nPlease enter the Q vector:\n')) R = np.array(input('\nPlease enter the R vector:\n')) print('\n\nP: ',P) print('Q: ',Q) print('R: ',R) #calculations for question 1 PQ=Q-P magPQ= sy.sqrt(dot(PQ,PQ)) #calculations for question 2 PR= R-P #calculations for question 3 QP = P-Q QR = R-Q magQP=sy.sqrt(dot(QP,QP)) magQR=sy.sqrt(dot(QR,QR)) angle=sy.arccos(dot(QP,QR)/(magQP*magQR)) angled=angle*180/sy.pi #calculations for question 4 Area = sy.sqrt(dot(cross(PQ,QR),cross(PQ,QR))) #calculations for question 5 magPR =sy.sqrt(dot(PR,PR)) perimeter = magPQ+magQR+magPR ######################OUTPUT####################### print("Question 1. What is the distance between P and Q?") print("Answer: ",round(q1,4)) print("\nQuestion 2. What is the distance vector from P to R?") print('Answer: ',q2) print("\nQuestion 3. What is the angle between QP and QR?") print('Answer: ',angled) print("\nQuestion 4. What is the area of the triangle PQR?") print('Answer: ',Area) print("\nQuestion 5. What is the perimeter of triangle PQR?") print('Answer: ',perimeter)

Above is my code, when I try to compile, I get the error

Traceback (most recent call last):
File "Homework1-3.py", line 17, in <module>
PQ=Q-P
TypeError: ufunc 'subtract' did not contain a loop with signature matching types dtype('<U6') dtype('<U6') dtype('<U6')
It's pretty important I am able to input my arrays because I would like this program to be able to solve problems. It seems like its using string instead of float. How could I fix this?
                np.array(input('Please enter the P vector:\n')) - are you expecting that to parse the string the user types? np.array doesn't do that.
– user2357112
                Jun 2, 2016 at 19:50
                If you were using this code on Python 2, input was calling eval on the string (which is a terrible idea and rightfully changed in Python 3). You also had other problems, like using print wrong.
– user2357112
                Jun 2, 2016 at 19:57
                I fixed the print for python 3 because it was the first set of error messages thrown out.
– Jacob Whitten
                Jun 2, 2016 at 20:00
In [375]: np.array(x)
Out[375]: 
array('123,232,232',    # trying to make that an array - still string
      dtype='<U11')
In [377]: np.array(x.split(','))
Out[377]: 
array(['123', '232', '232'],     # better - 3 strings 
      dtype='<U3')
In [378]: np.array(x.split(','),dtype=float)
Out[378]: array([ 123.,  232.,  232.])    # good
I'd strongly suggest you fire up an interactive Python session, and test each step of the code.  Get it working piece by piece.  Writing a whole script that has bugs right at the start is not a productive way to program - or to learn.
And when using numpy arrays, look at the shape and dtype; do not assume that the array is something meaningful or useful.  Check it.
                Thank you, and wise words  although when I try the last line of code I recieve Traceback (most recent call last):File "Homework1-3.py", line 8, in <module>     P = np.array(P.split(','),dtype=float) AttributeError: 'numpy.ndarray' object has no attribute 'split'
– Jacob Whitten
                Jun 2, 2016 at 20:14
                You apply split to a string as produced by input, not to something that has been passed through np.array.
– hpaulj
                Jun 2, 2016 at 21:28
        
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