I have a data frame like shown below

  sample1 sample2 sample3 sample4 sample5  a P P I P P  b P A P P A  c P P P
P P  d P P P P P  e M P M A P  f P P P P P  g P P P A P  h P P P P P

I want to keep only those rows which have all "P" across all the columns.

Since the matrix is large (about 20,000 rows), I cannot do it in excel

Any special function that i can use?
-- 
*Chirag Gupta*

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