如何从多行字符串中提取特定信息

Question

I have extracted some invoice related information from email body to Python strings, my next task is to extract the Invoice numbers from the string. The format of emails could vary, hence it is getting difficult to find invoice number from the text. I also tried "Named Entity Recognition" from SpaCy but since in most of the cases the Invoice number is coming in next line from the heading 'Invoice' or 'Invoice#',the NER doesn't understand the relation and returns incorrect details.

Below are 2 examples of the text extracted from mail body:

Example - 1.

Dear Customer:
The past due invoices listed below are still pending. This includes the 
following:

Invoice   Date     Purchase Order  Due Date  Balance
8754321   8/17/17  7200016508      9/16/18   140.72
5245344   11/7/17  4500199620      12/7/18   301.54

We would appreciate quick payment of these invoices.

Example - 2.

Hi - please confirm the status of below two invoices.

Invoice#               Amount               Invoice Date       Due Date          
7651234                $19,579.06          29-Jan-19           28-Apr-19            
9872341                $47,137.20          27-Feb-19           26-Apr-19 

My problem is that if I convert this entire text to a single string then this becomes something like this:

Invoice   Date     Purchase Order  Due Date  Balance 8754321   8/17/17 
7200016508     9/16/18   140.72

As it is visible that the Invoice number (8754321 in this case) changed its position and doesn't follow the keyword "Invoice" anymore, which is more difficult to find.

My desired output is something like this:

Output Example - 1 - 

8754321
5245344

Output Example - 2 - 

7651234                
9872341        

I don't know how can I retrieve text just under keyword "Invoice" or "Invoice#" which is the invoice number.

Please let me know if further information is required. Thanks!!

Edit: The invoice number doesn't have any pre-defined length, it can be 7 digit or can be more than that.

Answer 1

Code per my comments.

email = '''Dear Customer:
The past due invoices listed below are still pending. This includes the 
following:

Invoice   Date     Purchase Order  Due Date  Balance
8754321   8/17/17  7200016508      9/16/18   140.72
5245344   11/7/17  4500199620      12/7/18   301.54

We would appreciate quick payment of these invoices.'''

index = -1
# Get first line of table, print line and index of 'Invoice'
for line in email.split('\n'):
    if all(x != x.lower() for x in line.split()) and ('Invoice' in line) and len(line) > 0:
        print('--->', line, ' --- index of Invoice:', line.find('Invoice'))
        index = line.find('Invoice')

Uses heuristic that the column header row is always camel case or capitals (ID). This would fail if say a heading was exactly 'Account no.' rather than 'Account No.'

# get all number at a certain index
for line in email.split('\n'):
     words = line[index:].split()
     if words == []: continue
     word = words[0]
     try:
         print(int(word))
     except:
         continue

Reliability here depends on data. So in my code Invoice column must be first of table header. ie you can't have 'Invoice Date' before 'Invoice'. Obviously this would need fixing.

Answer 2

Going off what Andrew Allen was saying, as long as these 2 assumptions are true:

1. Invoice numbers are always exactly 7 numerical digits
2. Invoice numbers are always following a whitespace and followed by a whitespace

Using regex should work. Something along the lines of;

import re

email = '''Dear Customer:
The past due invoices listed below are still pending. This includes the 
following:

Invoice   Date     Purchase Order  Due Date  Balance
8754321   8/17/17  7200016508      9/16/18   140.72
5245344   11/7/17  4500199620      12/7/18   301.54

We would appreciate quick payment of these invoices.'''

invoices = re.findall(r'\s(\d\d\d\d\d\d\d)\s', email)

invoice in this case has a list of 2 strings, ['8754321', '5245344']

Answer 3

Using Regex. re.findall

Ex:

import re

email = '''Dear Customer:
The past due invoices listed below are still pending. This includes the 
following:

Invoice   Date     Purchase Order  Due Date  Balance
8754321   8/17/17  7200016508      9/16/18   140.72
5245344   11/7/17  4500199620      12/7/18   301.54

We would appreciate quick payment of these invoices.'''

email2 = """Hi - please confirm the status of below two invoices.

Invoice#               Amount               Invoice Date       Due Date          
7651234                $19,579.06          29-Jan-19           28-Apr-19            
9872341                $47,137.20          27-Feb-19           26-Apr-19 """

for eml in [email, email2]:
    print(re.findall(r"\b\d{7}\b", eml, flags=re.DOTALL))

Output:

['8754321', '5245344']
['7651234', '9872341']

• \\b - regex boundaries
• \\d{7} - get 7 digit number