How to Increase index when value change

Hello experts ,

how to increas index when value change .

input--------------------------------- output

LMV31456823------------------------ 1

LMV31456823------------------------ 1

LMV32265314------------------------- 2

LMV32265314--------------------------2

LMV32265314--------------------------2

LMV322653153------------------------3

Thanks in advance

input is

<Packages>

<Parts>

<partNumber>LMV31456823</partNumber>

</Parts>

</Packages>

<Packages>

<Parts>

<partNumber>LMV31456823</partNumber>

</Parts>

</Packages>

<Packages>

<Parts>

<partNumber>LMV32265314</partNumber>

</Parts>

</Packages>

<Packages>

<Parts>

<partNumber>LMV32265314</partNumber>

</Parts>

</Packages>

<Packages>

<Parts>

<partNumber>LMV32265314</partNumber>

</Parts>

</Packages>

<Packages>

<Parts>

<partNumber>LMV32265315</partNumber>

</Parts>

</Packages>

and the output should be

<E1EDL37 SEGMENT="1">

<E1EDL44 SEGMENT="1">

<POSNR>1</POSNR>

</E1EDL44>

</E1EDL37>

<E1EDL37 SEGMENT="1">

<E1EDL44 SEGMENT="1">

<POSNR>1</POSNR>

</E1EDL44>

</E1EDL37>

<E1EDL37 SEGMENT="1">

<E1EDL44 SEGMENT="1">

<POSNR>2</POSNR>

</E1EDL44>

</E1EDL37>

<E1EDL37 SEGMENT="1">

<E1EDL44 SEGMENT="1">

<POSNR>2</POSNR>

</E1EDL44>

</E1EDL37>

<E1EDL37 SEGMENT="1">

<E1EDL44 SEGMENT="1">

<POSNR>2</POSNR>

</E1EDL44>

</E1EDL37>

<E1EDL37 SEGMENT="1">

<E1EDL44 SEGMENT="1">

<POSNR>3</POSNR>

</E1EDL44>

</E1EDL37>