How to write decoded data matrix to dataframe

Question

I'm trying to read all data matrixes from an image and write to dataframe. I can print barcode number and location via pylibdmtx but I can't figure out how to store in dataframe

image = cv2.imread('IMG-4951.jpg')
gray = cv2.cvtColor(image, cv2.COLOR_RGB2GRAY)
plt.imshow(gray)
ret,thresh = cv2.threshold(gray, 0, 255, cv2.THRESH_BINARY | cv2.THRESH_OTSU)
msg = pylibdmtx.decode(thresh)
print(msg)


Output:
[Decoded(data=b'01086995460155972150046789702417240229109LB02199', rect=Rect(left=984, top=1172, width=290, height=287)), Decoded(data=b'01086995460155972154702360250417240229109LB02199', rect=Rect(left=899, top=2242, width=279, height=272))]

'msg' variable stored as list with 2 elements in this case and when I try to convert pandas Dataframe 'data' column is blank but 'rect' column is proper like above. (Rect(left=984, top=1172, width=290, height=287))

Dataframe looks like below;

data      rect
          Rect(left=984, top=1172, width=290, height=287)
          Rect(left=899, top=2242, width=279, height=272)

How can I fill data column or any other method do you suggest?

My second question is, this library seems very slow any suggestion how to make it quicker?

Thanks in advance,

Answer 1

This might be helpful

I used this test image

Import the packages

import cv2
import matplotlib.pyplot as plt
from pylibdmtx.pylibdmtx import decode
import pandas as pd 

Use the code you provided above

image = cv2.imread('datamatrix.png')
gray = cv2.cvtColor(image, cv2.COLOR_RGB2GRAY)
plt.imshow(gray)
ret,thresh = cv2.threshold(gray, 0, 255, cv2.THRESH_BINARY | cv2.THRESH_OTSU)
msg = decode(thresh)
print(msg)

I get this output,

[Decoded(data=b'Stegosaurus', rect=Rect(left=5, top=6, width=96, height=95)), Decoded(data=b'Plesiosaurus', rect=Rect(left=298, top=6, width=95, height=95))]

To add to a dataframe I start with populating a list to represent the shape I would like the dataframe to be

ls_msg = []
for item in msg:
    ls_msg.append([item[0], item[1][0], item[1][1], item[1][2]])

Make list into a dataframe

df_msg = pd.DataFrame(ls_msg)

Add column names

df_msg.columns = ['data', 'left','top','width']

This produces a dataframe which looks like this

Never used this package before it was fascinating to install and play!