如何使用正则表达式查找某个单词下的数字？

Question

Trying to get the number 811.00 when its placed under the word Size .

I know how to get the number when its NEAR some word, like "Jerusalem" in this case.
But here I'm trying to get the number when it's under the word Size .

Property Size
Jerusalem 811.00
A new property agreement

Thanks, Couldn't Find any solution for this.

Answer 1

This can be accomplished by a technique introduced in vertical regex matching and requires a regex flavor with support for possessive quantifiers and forward references like PCRE or Java .

I don't know if it's worth the effort but it's certainly an interesting task by use of regex. I found the biggest challenge to keep the start of the number below above words boundaries to the left and right. In the following pattern I tried to only catch full numbers and prevent any partial matching.

^(?:.(?=.*\n(\1?+.)))*?(?=Size)(?:\w\B(?=.*\n\1?+(\2?+\D)))*+.*\n\1?+\2?+(?<![\d.])([\d.]+)

regex-part	explained
^(?:.(?=.*\n(\1?+.)))*?(?=Size)	captures substring from below line up to above word to $1 the first group is growing at each repetition by one character
(?:\w\B(?=.*\n\1?+(\2?+\D)))*+	captures any non-digits matching above words length to $2 \B (non word boundary) prevents skipping over the margin
.*\n\1?+\2?+(?<.[\d.])([\d.]+)	consumes what is captured and capturing the number to $3 the negative lookbehind prevents matching numbers partially

See this demo at regex101 or a PHP demo at tio.run - The number will be found in the third group .

Also works with .NET by getting around the possessive quantifiers using atomic groups ( C# demo ).
In Notepad++ ([\d.]+) can be replaced with \K[\d.]+ to reset before and finding the numbers.

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More about how it works can further be found in this answer about matching a letter below another .

Answer 2

One solution would be to count the index of 'Size' within the first header row of the output and then use that information to extract the value under 'Size':

(?<=(\w\s){1}?)(\d+.\d+)

In the example you provided, 'Size' is the second attribute in the row, so there is one word and a space preceding the value you desire (\w\s){1}, we also know that the value is a decimal (\d+.\d+). If there were 3 attributes, you would replace the 1 with a 2...

Note: this solution assumes that every value under each attribute is a single word.