pandas long

gistfile1.txt

df_long = pd.DataFrame(
  {"student": ["Andy", "Bernie", "Cindy", "Deb", "Andy", "Bernie", "Cindy", "Deb", "Andy", "Bernie", "Cindy", "Deb"],
   "school":  ["Z", "Y", "Z", "Y", "Z", "Y", "Z", "Y", "Z", "Y", "Z", "Y"],
   "class":   ["english", "english", "english", "english", "math", "math", "math", "math", "physics", "physics", "physics", "physics"],
   "grade":   [10, 100, 1000, 10000, 20, 200, 2000, 20000, 30, 300, 3000, 30000]
  }
)

df_long
>    student school    class  grade
  0     Andy      Z  english     10
  1   Bernie      Y  english    100
  2    Cindy      Z  english   1000
  3      Deb      Y  english  10000
  4     Andy      Z     math     20
  5   Bernie      Y     math    200
  6    Cindy      Z     math   2000
  7      Deb      Y     math  20000
  8     Andy      Z  physics     30
  9   Bernie      Y  physics    300
  10   Cindy      Z  physics   3000
  11     Deb      Y  physics  30000