Don't understand this SyntaxError: illegal target for annotation

问题

I have some simple if... elif... in my python3.6 (& OpenCV 4.0), but no matter what I do I keep getting strange error messages.

I need to crop some pics according to some bounding boxes.

# the image to be cropped loads here:
tobecropped= cv2.imread(img)
images.append(tobecropped)
(imageheight, imagewidth) = tobecropped.shape[:2]

# sample bounding box:
y = 833 # center vertically
x = 183 # center horizontally
width = 172
height = 103

# calculation of cropping values adding 10% extra:
y1 = y-(height/2*1.1)
y2 = y+(height/2*1.1)
x1 = x-(width/2*1.1)
x2 = x+(width/2*1.1)

# return values to int:
y1 = int(y1)
y2 = int(y2)
x1 = int(x1)
x2 = int(x2)

# move the cropping inside the original image:
If (y1 < 0): y_movedown()
Elif (y2 > imageheight): y_moveup()
Elif (x1 < 0) : x_moveright()
Elif (x2 > imagewidth): x_moveleft()

# actually cropping the image:
cropped = tobecropped[y1:y2, x1:x2]
cv2.imshow("cropped", cropped)

# functions to move the complete bounding box inside the image boundaries:
def y_movedown():
    y2=y2-y1
    y1=0
    print("moved down!")

def y_moveup():
    y1=y1-(y2-imageheight)
    y2=imageheight
    print("moved up!")

def x_moveright():
    x2=x2-x1
    x1=0
    print("moved right!")

def x_moveleft():
    x1=x1-(x2-imagewidth)
    x2=imagewidth
    print("moved left!")

the error message looks like this:

File "image_import2.py", line 121
   If (y1 < 0): y_movedown()
   ^
SyntaxError: illegal target for annotation

Does anyone see, what I am doing wrong here? Could not find any mention of such a mistake...

回答1:

Look at these lines:

If (y1 < 0): y_movedown()
Elif (y2 > imageheight): y_moveup()
Elif (x1 < 0) : x_moveright()
Elif (x2 > imagewidth): x_moveleft()

If, Elif are titled words, when they should be lowercase, so do:

if (y1 < 0): y_movedown()
elif (y2 > imageheight): y_moveup()
elif (x1 < 0) : x_moveright()
elif (x2 > imagewidth): x_moveleft()

Instead.

来源：https://stackoverflow.com/questions/53734530/dont-understand-this-syntaxerror-illegal-target-for-annotation

标签

python

python-3.x

if-statement

syntax-error

conditional