Creating Bounding box for 2D pdf file

Hi,

This is regarding creating of bounding box on PDF file

Assume we can get bounding box details from another source.

And that is for whole string 18"-1S6(10S)-471454, using that need create bounding box for 471454.

To find the differences we manually created the two bounding box 

Below are the bounding box details also attached the  screenshot.

#smaller bounding box
"textRegion": {
                "xMax": 0.12297021616798368,
                "xMin": 0.10935503986439225,
                "yMax": 0.6030244780685147,
                "yMin": 0.5957594432410297
            }

 Bigger bounding box we got from XML

#bigger bounding box
"textRegion": {
                "xMax": 0.1245098493906997,
                "xMin": 0.0782598493906997,
                "yMax": 0.6047371474808384,
                "yMin": 0.5915995895210239
            }

So we can observe if we can reduce only xmin and we create  bounding box for 471454 and keep all other values same.

As we have to do this for lots of places in PDF, can we get any formula to “reduce Xmin based on bigger bounding box xmin” and use String length.???