Error in plotting line graph

Question

Appreciate it if someone could explain to me what went wrong?

1) Couldnt plot line graph....I managed to plot my data only with point marker('r.') or round marker('r.'), the plot just blank with no data when I tried to plot it with line graph changing it to ('r-')

Below is my code to produce the figure and also the data printed out

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


path = 'R:\\Temp\\xxx\\'
path1 = 'R:\\Temp\\xxx\\'

def Hue(im_file):
    im = cv2.imread(im_file)
    im = cv2.cvtColor(im, cv2.COLOR_BGR2HSV_FULL)
    im1 = im[776, 402]
    Hue = im1[0]
    return Hue

def Saturation(im_file):
    im = cv2.imread(im_file)
    im = cv2.cvtColor(im, cv2.COLOR_BGR2HSV_FULL)
    im1 = im[776, 402]
    Saturation = im1[1]
    return Saturation

def Value(im_file):
    im = cv2.imread(im_file)
    im = cv2.cvtColor(im, cv2.COLOR_BGR2HSV_FULL)
    im1 = im[776, 402]
    Value = im1[2]
    return Value   

def BlueComponent(im_file):
    im = cv2.imread(im_file) #return blue value
    im1 = im[776, 402]
    b = im1[0]
    return b

def GreenComponent(im_file):
    im = cv2.imread(im_file) #return green value 
    im1 = im[776, 402]
    g = im1[1]
    return g

def RedComponent(im_file): #return red value 
    im = cv2.imread(im_file)
    im1 = im[776, 402]
    r = im1[2]
    return r

myHueList = []
mySaturationList = []
myValueList = []
myBlueList = []
myGreenList = []
myRedList = []
myList = []
num_images = 99 # number of images

dotPos = 0
for i in range(1770, 1869): # loop to auto-generate image names and run prior function 
    image_name = path + 'Cropped_Aligned_IMG_' + str(i) + '.png' # for loop runs from image number 1770 to 1868
    myHueList.append(Hue(image_name))
    mySaturationList.append(Saturation(image_name))
    myValueList.append(Value(image_name))
    myBlueList.append(BlueComponent(image_name))
    myGreenList.append(GreenComponent(image_name))
    myRedList.append(RedComponent(image_name))
    myList.append(dotPos)
    dotPos = dotPos + 0.5

print(myHueList)
print(mySaturationList)
print(myValueList)
print(myList)
print(myBlueList)
print(myGreenList)
print(myRedList)


for k in range(1770,1869):
    a = 'Cropped_Aligned_IMG_' + str(k)
    image_name = path + a + '.png'
    img_file = cv2.imread(image_name)

y = [myBlueList]
x = [myList]
y1 = [myGreenList]
y2 = [myRedList]
y3 = [myHueList]
y4 = [mySaturationList]
y5 = [myValueList]


plt.axes([0.1, 0.1, 1, 1])
plt.suptitle('BGR & HSV Color Decimal Code Against Function of Time(Hours)', fontsize=14, fontweight='bold')
plt.subplot(3,2,1)
plt.plot(x, y, 'b.-')
plt.title('Blue Component Color Decimal Code')
plt.xlabel('Time(Hours)')
plt.ylabel('Colour Code')

plt.subplot(3,2,3)
plt.plot(x, y1, 'g.-')
plt.title('Green Component Color Decimal Code')
plt.xlabel('Time(Hours)')
plt.ylabel('Colour Code')

plt.subplot(3,2,5)
plt.plot(x, y2, 'r.-')
plt.title('Red Component Color Decimal Code')
plt.xlabel('Time(Hours)')
plt.ylabel('Colour Code')

plt.subplot(3,2,2)
plt.plot(x, y3, 'b.-')
plt.title('Hue Component HSV Color Decimal Code')
plt.xlabel('Time(Hours)')
plt.ylabel('Colour Code')

plt.subplot(3,2,4)
plt.plot(x, y4, 'g.-')
plt.title('Saturation Component HSV Color Decimal Code')
plt.xlabel('Time(Hours)')
plt.ylabel('Colour Code')

plt.subplot(3,2,6)
plt.plot(x, y5, 'r.-')
plt.title('Value Component HSV Color Decimal Code')
plt.xlabel('Time(Hours)')
plt.ylabel('Colour Code')
plt.subplots_adjust(hspace = 0.5)
plt.show()

I have copy out the data as below:

myHueList = [5, 4, 5, 5, 5, 5, 6, 5, 5, 5, 5, 5, 5, 5, 4, 4, 4, 5, 5, 5, 6, 6, 6, 6, 7, 5, 5, 6, 5, 6, 5, 5, 5, 5, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 4, 6, 6, 5, 6, 6, 6, 6, 5, 4, 4, 5, 6, 6, 5, 6, 6, 6, 4, 4, 4, 5, 6, 5, 4, 5, 5, 5, 5, 4, 4, 5, 5, 4, 3, 5, 3, 3, 3, 2, 1, 3, 3, 4, 1, 1, 1, 0, 2, 0, 1, 1, 2, 2, 2]

mySaturationList = [99, 95, 102, 99, 98, 102, 99, 99, 96, 99, 102, 100, 99, 95, 94, 102, 105, 98, 97, 107, 105, 104, 107, 102, 109, 102, 101, 102, 96, 102, 105, 97, 100, 97, 99, 100, 99, 100, 99, 100, 106, 100, 102, 99, 96, 104, 102, 102, 104, 104, 100, 99, 95, 101, 105, 96, 101, 101, 107, 100, 105, 102, 100, 97, 103, 104, 106, 99, 96, 97, 97, 97, 104, 93, 96, 98, 101, 93, 88, 93, 83, 84, 82, 79, 78, 83, 78, 79, 80, 74, 72, 75, 75, 71, 71, 66, 74, 76, 73]

myValueList = [137, 134, 133, 137, 138, 133, 139, 136, 135, 131, 123, 135, 137, 132, 135, 125, 121, 133, 134, 121, 134, 135, 119, 137, 133, 123, 134, 125, 135, 138, 121, 134, 135, 139, 137, 138, 142, 135, 137, 135, 135, 135, 133, 131, 133, 123, 132, 137, 123, 135, 135, 141, 142, 137, 122, 136, 137, 137, 121, 138, 134, 138, 127, 140, 124, 137, 125, 137, 130, 139, 140, 139, 123, 137, 135, 128, 134, 137, 136, 134, 142, 139, 143, 139, 137, 144, 138, 149, 127, 141, 142, 136, 143, 136, 141, 135, 144, 141, 144]

myList = [0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12.0, 12.5, 13.0, 13.5, 14.0, 14.5, 15.0, 15.5, 16.0, 16.5, 17.0, 17.5, 18.0, 18.5, 19.0, 19.5, 20.0, 20.5, 21.0, 21.5, 22.0, 22.5, 23.0, 23.5, 24.0, 24.5, 25.0, 25.5, 26.0, 26.5, 27.0, 27.5, 28.0, 28.5, 29.0, 29.5, 30.0, 30.5, 31.0, 31.5, 32.0, 32.5, 33.0, 33.5, 34.0, 34.5, 35.0, 35.5, 36.0, 36.5, 37.0, 37.5, 38.0, 38.5, 39.0, 39.5, 40.0, 40.5, 41.0, 41.5, 42.0, 42.5, 43.0, 43.5, 44.0, 44.5, 45.0, 45.5, 46.0, 46.5, 47.0, 47.5, 48.0, 48.5, 49.0]

myBlueList = [84, 84, 80, 84, 85, 80, 85, 83, 84, 80, 74, 82, 84, 83, 85, 75, 71, 82, 83, 70, 79, 80, 69, 82, 76, 74, 81, 75, 84, 83, 71, 83, 82, 86, 84, 84, 87, 82, 84, 82, 79, 82, 80, 80, 83, 73, 79, 82, 73, 80, 82, 86, 89, 83, 72, 85, 83, 83, 70, 84, 79, 83, 77, 87, 74, 81, 73, 84, 81, 86, 87, 86, 73, 87, 84, 79, 81, 87, 89, 85, 96, 93, 97, 96, 95, 97, 96, 103, 87, 100, 102, 96, 101, 98, 102, 100, 102, 99, 103]

myGreenList = [90, 89, 86, 90, 91, 86, 92, 89, 90, 86, 80, 88, 90, 89, 90, 80, 76, 88, 89, 76, 87, 88, 76, 90, 86, 80, 87, 82, 90, 91, 77, 89, 88, 92, 89, 89, 93, 88, 90, 88, 86, 88, 86, 86, 88, 80, 86, 88, 80, 88, 89, 94, 95, 88, 77, 91, 90, 90, 76, 91, 87, 91, 82, 92, 79, 88, 80, 90, 86, 92, 93, 92, 79, 92, 89, 85, 87, 92, 92, 91, 99, 96, 100, 98, 96, 100, 99, 107, 88, 101, 103, 96, 103, 98, 103, 101, 104, 101, 105]

myRedList = [137, 134, 133, 137, 138, 133, 139, 136, 135, 131, 123, 135, 137, 132, 135, 125, 121, 133, 134, 121, 134, 135, 119, 137, 133, 123, 134, 125, 135, 138, 121, 134, 135, 139, 137, 138, 142, 135, 137, 135, 135, 135, 133, 131, 133, 123, 132, 137, 123, 135, 135, 141, 142, 137, 122, 136, 137, 137, 121, 138, 134, 138, 127, 140, 124, 137, 125, 137, 130, 139, 140, 139, 123, 137, 135, 128, 134, 137, 136, 134, 142, 139, 143, 139, 137, 144, 138, 149, 127, 141, 142, 136, 143, 136, 141, 135, 144, 141, 144]

If you have two questions, which are unrelated, ask two questions. The first problem is due to the points being in a list of a list instead of a single list. The second problem may be solved as shown in [this question](https://stackoverflow.com/questions/27426668/row-titles-for-matplotlib-subplot). — ImportanceOfBeingErnest, Aug 18 '17 at 11:13

score 3 · Accepted Answer · answered Aug 18 '17 at 12:33

The data is stored in a list of a list. I.e. you have [[1,2,3]] instead of [1,2,3]. This will not be understood correctly by matplotlib, such that no lines are drawn in between the points.

To correctly produce the required lists, use

y = myBlueList
x = myList
y1 = myGreenList
y2 = myRedList
y3 = myHueList
y4 = mySaturationList
y5 = myValueList

Error in plotting line graph

1 Answers1