1

hi i want to read 8 numerical columns from some txt files for calculating average of these numbers.
indeed i want to make label files that are suitable for training Yolo V5 for an object detection task (using Google Earth Images)
i have some label files (for some images) that contain coordinates of 4 corners for bounding boxes around objects (instances) into my images.
i wrote below codes for reading these numbers (coordinates) from txt files and then i want to calculate average of x1,x2,x3 and x4 and average of y1,y2,y3 and y4 and calculate width and height for bounding boxes. finally normalize them (0 to 1).

from google.colab import drive
drive.mount('/content/drive')
file_path = ('/content/drive/MyDrive/labelfiles/P0002_ColabFormat.txt')
def read_bounding_boxes_from_file(file_path):
    with open(file_path, 'r') as file:
        lines = file.readlines()
        bounding_boxes = []
        for line in lines:
            # Split each line into individual numbers
            coordinates = [int(coord) for coord in line.strip().split()]
            # Check if the line contains at least 8 coordinates (2 points)
            if len(coordinates) >= 8:
                # Reshape the coordinates into pairs of (x, y) tuples
                bbox = [(coordinates[i], coordinates[i+1]) for i in range(0, len(coordinates), 2)]
                bounding_boxes.append(bbox)
    return bounding_boxes
def calculate_center_and_dimensions(bbox):
    # Extract corner coordinates
    # image P0002
    image_width = 2557
    image_height = 2086
    x1, y1 = bbox[0]  # Top-left corner
    x2, y2 = bbox[1]  # Top-right corner
    x3, y3 = bbox[2]  # Bottom-right corner
    x4, y4 = bbox[3]  # Bottom-left corner

        # Calculate center coordinates
    x_center = (x1 + x2 + x3 + x4) / 4
    y_center = (y1 + y2 + y3 + y4) / 4

    # Calculate width and height
    width = max(x1, x2, x3, x4) - min(x1, x2, x3, x4)
    height = max(y1, y2, y3, y4) - min(y1, y2, y3, y4)

    x_center /= image_width
    y_center /= image_height
    width /= image_width
    height /= image_height

    return x_center, y_center, width, height





# Example usage
oriented_bbox = [bounding_boxes]  # Example oriented bounding box coordinates
x_center, y_center, width, height = calculate_center_and_dimensions(oriented_bbox)
print("Center coordinates (x_center, y_center):", x_center, y_center)
print("Dimensions (width, height):", width, height)

but colab shows below error message:

ValueError Traceback (most recent call last)
in <cell line: 48>()
46 # Example usage
47 oriented_bbox = [bounding_boxes] # Example oriented bounding box coordinates
—> 48 x_center, y_center, width, height = calculate_center_and_dimensions(oriented_bbox)
49 print(“Center coordinates (x_center, y_center):”, x_center, y_center)
50 print(“Dimensions (width, height):”, width, height)

in calculate_center_and_dimensions(bbox)
20 image_width = 2557
21 image_height = 2086
—> 22 x1, y1 = bbox[0] # Top-left corner
23 x2, y2 = bbox[1] # Top-right corner
24 x3, y3 = bbox[2] # Bottom-right corner

ValueError: too many values to unpack (expected 2)

2

Hi,

note that the variable bounding_boxes is local to the function read_bounding_boxes_from_file. It has no scope outside of the function definition.

What you might want is:

oriented_bbox = read_bounding_boxes_from_file(file_path)

This will return that variable value and assign it to the oriented_bbox variable.

Just as a heads up. During your script development phase, and with regards to functions that return values, include a print statement printing the variable(s) to be returned as a sanity check to verify that it is in the correct format, the expected value or both. This is a temporary print statement that you can remove in the final script version but helps in the verification in real time. It helps catch bugs before they propagate to other parts of a script.

3

This cannot get you the information back from the function. First off, it has not been called. Second, return values do not work that way.

This is the right way to do it. You must use read_bounding_boxes_from_file in a similar way: oriented_bbox = read_bounding_boxes_from_file(file_path). We must tell it the file path directly, because it is looking for a parameter, so we supply an argument for it. It will not use the global just because it has the right name.

More information:

5

hi thanks a lot. my codes work correctly
please look at below correct codes:

def read_bounding_boxes_from_file(file_path):
    with open(file_path, 'r') as file:
        lines = file.readlines()
        bounding_boxes = []
        for line in lines:
            # Split each line into individual numbers
            coordinates = [int(coord) for coord in line.strip().split()]
            # Check if the line contains at least 8 coordinates (4 points)
            if len(coordinates) >= 8:
                # Reshape the coordinates into pairs of (x, y) tuples
                bbox = [(coordinates[i], coordinates[i + 1]) for i in range(0, len(coordinates), 2)]
                bounding_boxes.append(bbox)
        return bounding_boxes

def calculate_center_and_dimensions(bbox):
    # Extract corner coordinates
    x1, y1 = bbox[0]  # Top-left corner
    x2, y2 = bbox[1]  # Top-right corner
    x3, y3 = bbox[2]  # Bottom-right corner
    x4, y4 = bbox[3]  # Bottom-left corner
    
    # Calculate center coordinates
    x_center = (x1 + x2 + x3 + x4) / 4
    y_center = (y1 + y2 + y3 + y4) / 4
    
    # Calculate width and height
    width = max(x1, x2, x3, x4) - min(x1, x2, x3, x4)
    height = max(y1, y2, y3, y4) - min(y1, y2, y3, y4)
    
    return x_center, y_center, width, height

def normalize_bounding_boxes(bounding_boxes, image_width, image_height):
    normalized_boxes = []
    for bbox in bounding_boxes:
        # Calculate center coordinates, width, and height
        x_center, y_center, width, height = calculate_center_and_dimensions(bbox)
        # Normalize coordinates by image width and height
        x_center /= image_width
        y_center /= image_height
        width /= image_width
        height /= image_height
        normalized_boxes.append((x_center, y_center, width, height))
    return normalized_boxes

# Example usage
file_path = '/content/drive/My Drive/labelfiles/P0002_ColabFormat.txt'
bounding_boxes = read_bounding_boxes_from_file(file_path)
print("Bounding boxes read from file:")
for bbox in bounding_boxes:
    print(bbox)

# Example image dimensions
image_width = 2557
image_height = 2086
normalized_bounding_boxes = normalize_bounding_boxes(bounding_boxes, image_width, image_height)
print("\nNormalized bounding boxes:")
for bbox in normalized_bounding_boxes:
    print(bbox)