segregate vs weed out

segregate

verb
  • To separate, especially by social policies that directly or indirectly keep races or ethnic groups apart. 

adj
  • Separated from others of the same kind. 

  • Separate from a mass and collected together along lines of fraction. 

  • Separate; select. 

weed out

verb
  • to remove unwanted elements from a group 

How often have the words segregate and weed out occurred in a corpus of books? (source: Google Ngram Viewer )