Find a string from group of string and take the value using php

we have a group of string like white-1,black-2,blue-4 etc . This is the string format .

ie : name1-name1 value , name2-name2 value etc .

From this string i need to take the associated value . For example value of white is 1 , value of blue is 4 etc .

How can i do this ?