ValueError(f"x and y must have same first dimension, but " ValueError: x and y must have same first dimension, but have shapes (6,) and (1)

Question

I'm detecting contours in a video and calculating each angular displacement. Now I want to plot the angular velocities over time but I keep getting this error ValueError(f"x and y must have same first dimension, but " ValueError: x and y must have same first dimension, but have shapes (6,) and (1). Below is the code

import cv2
import numpy as np
import skimage.morphology
import matplotlib.pyplot as plt


# Load video
cap = cv2.VideoCapture("test2.mp4")

# get frame rate and frame count
fps = int(cap.get(cv2.CAP_PROP_FPS))
totalFrames = int(cap.get(cv2.CAP_PROP_FRAME_COUNT))

# get total duration of the video
total_duration = totalFrames / fps

... calculate prev_angle

while True:
ret, nFrame = cap.read()
if not ret:
    break

roi = nFrame[304:547, 685:1044]

... pre-process roi

# find contours
newContours, _ = cv2.findContours(roi_thresh, cv2.RETR_EXTERNAL, 
cv2.CHAIN_APPROX_SIMPLE)

angular_velocities = []
displacements = []
time = []

# Calculate angle of the contours
for i in range(len(newContours)):
    for j in range(i, len(newContours)):
        new_c1 = newContours[i]
        new_c2 = newContours[j]

        x1, y1, w1, h1 = cv2.boundingRect(new_c1)
        x2, y2, w2, h2 = cv2.boundingRect(new_c2)
      
        # find centroid of each contours
        newM1 = cv2.moments(new_c1)
        if newM1['m00'] != 0:
            new_cx1 = int(newM1['m10'] / newM1['m00'])
            new_cy1 = int(newM1['m01'] / newM1['m00'])
        else:
            new_cx1, new_cy1 = 0, 0

        # view the centre of contour
        cv2.circle(roi, (new_cx1, new_cy1), 3, (0, 0, 255), -1)

        newM2 = cv2.moments(new_c2)
        if newM2['m00'] != 0:
            new_cx2 = int(newM2['m10'] / newM2['m00'])
            new_cy2 = int(newM2['m01'] / newM2['m00'])
        else:
            new_cx2, new_cy2 = 0, 0

        # view the center of contour
        cv2.circle(roi, (new_cx2, new_cy2), 4, (0, 255, 0), 1)

        newAngle = np.arctan2(new_cy2 - new_cy1, new_cx2 - new_cx1)
        newAngle = (np.rad2deg(newAngle))
        # newAngle = (newAngle + 180) % 360 - 180
        # print("Angle between contour {} and {} is {:.2f} degrees".format(i+1, j, newAngle)) #working

        cv2.drawContours(roi, [new_c1, new_c2], 0, (0, 0, 255), 1)
        text = "C" + str(i+1)
        cv2.putText(roi, text, (new_cx1, new_cy1), cv2.FONT_HERSHEY_SIMPLEX, 0.5, (255, 255, 255), 1)


    # calulate angular displacement
    delta_angle = newAngle - prev_angle
    print("Angular displacement of contour {} is {:.2f} degrees".format(i+1, delta_angle))  # working
    prev_angle = newAngle
    displacements.append(delta_angle)
    time = [i/fps for i in range(len(displacements))]

    current_Frame = int(cap.get(cv2.CAP_PROP_POS_FRAMES))
    
    delta_t = (current_Frame - prev_Frame) / fps
   
    angularVelocity = delta_angle / delta_t if delta_t != 0 else 0

    # skeltonize
    threshSkeleton = (roi_thresh / 255).astype(np.float64)
    skeleton = skimage.morphology.skeletonize(threshSkeleton)
    skeleton = (255 * skeleton).clip(0, 255).astype(np.uint8)

    # Thickness
    cntr = newContours[i]
    length = cv2.arcLength(cntr, True)
    # print("length of contour {}: {:.2f}".format(i+1, length))
    area = cv2.contourArea(newContours[i])
    if length == 0:
        continue
    thickness = (area / length) * 0.264
    # print("Thickness of contour {} is {:.2f} mm".format(i+1, thickness)) #working

angular_velocities.append(angularVelocity)

prev_Frame = current_Frame
current_Frame = int(cap.get(cv2.CAP_PROP_POS_FRAMES))
# time.append(current_Frame / fps)
# time = current_Frame/fps


# cv2.imshow("ROI", roi)
cv2.imshow("frame", nFrame)

if cv2.waitKey(1) & 0xFF == ord('q'):
    break
cap.release()

# plt.plot(angular_velocities)

for i in range(len(displacements)):
  plt.plot(time, displacements[i], label='Contour{}'.format(i + 1))
plt.xlabel("Time (s)")
plt.ylabel('Angular displacement (degrees per second)')
plt.title('Angular displacement over time')
plt.show()

any help is highly appreciated. Also if there are any other errors, please do let me know. Thanks