automatic extracting number from a text with given signs

Question

I am trying to get a number from a plaintext with the staring sign of "Nho xanh không hạt" and ending sign of "đ" automatically with different method but it doesn't work. In detail, I want to get the number "99.500" from the first text and "275,000" from the second text as:

textin = "Nho xanh không hạt"

url2a = "https://www.bachhoaxanh.com"
url2b = "https://nongsandungha.com"

result2a = 
 WebSearch[textin, "Snippets", "Site" -> url2a, Method -> "Google"]

result2b = 
 WebSearch[textin, "Snippets", "Site" -> url2b, Method -> "Google"]

StringCases[result2a, textin ~~ _ ~~ "đ"]

StringCases[result2b, textin ~~ _ ~~ "đ"]

TextCases[result2a, "CurrencyAmount" -> "Interpretation"]

TextCases[result2b, "CurrencyAmount" -> "Interpretation"]

StringCases[[result2a, 
  textin ~~ _ ~~ StringEndsQ[#, "đ"] &], DigitCharacter]

StringCases[[result2b, 
  textin ~~ _ ~~ StringEndsQ[#, "đ"] &], DigitCharacter]

Could you please suggest me how to obtain the above number? Thank you in advance.

Answer 1

Note that many websites will not let you have their plaintext easily, if at all. There are all sorts of wrappers around useful information. That's why search is a lucrative business. Having said that, if a string search is your problem and you are going with the plaintext route; try the following example (without going through any company's server as there will always be some limit that will kick in sooner or later on what you can do there):

ptext = Import["https://www.bachhoaxanh.com", "Plaintext"]

The resulting text has many entries of the form:

    Rau cải bẹ xanh 4KFarm gói 500g  
  11.000₫   15.000₫   -27%     Chọn mua  

   
       Rau cải thìa tươi 4KFarm gói 500g  
  11.000₫   15.000₫   -27%     Chọn mua  
 
 
Xem trực tiếp         
Khoai lang Nhật dẻo ngọt túi 1kg  
  35.000₫     Chọn mua  
 
      
Táo Gala mini nhập khẩu hộp 1kg  
  49.000₫     Chọn mua

I believe the last word "Chọn mua" stands for "buy". As an example, let's try to get one of these products.

astr = StringCases[ptext, 
  "Rau cải bẹ xanh" ~~ Shortest[___] ~~ "Chọn mua "]

{"Rau cải bẹ xanh 4KFarm gói 500g  
  11.000₫   15.000₫   -27%     Chọn mua "}

For the interested reader, this is a list with string(s) inside it.

tcases = TextCases[#, "CurrencyAmount" -> "Interpretation"] & /@ 
   astr // Flatten[#, 1] &

{Quantity[11., "VietnameseDong"], Quantity[15., "VietnameseDong"]}

You can extract the first quantity with First@tcases.

---

If you want to extract (let's say 500g, for products with different weights) it is often not so easy. My first attempt is as follows:

wcases = StringCases[#, DigitCharacter .. ~~ LetterCharacter ..] & /@ 
   astr // Flatten[#, 1] &

{"4KFarm", "500g"}

The way data is presented will change from website to website. Often it is not easy to get the data without tailored attempts.

I hope this helps you. I have no knowledge of Vietnamese so please do forgive me the lapses.