HelloDarknessMyOldFried

import pandas as pd

df1 = pd.DataFrame({'col1':['A', 'B', 'C', 'D', 'C'], 'col2': [1,2,3,4,3], 'col3': [5,6,7,8,102]})
df1

df2 = pd.DataFrame({'col1':['C'], 'col2': [3], 'col3': [7]})
df2


df_new = pd.merge(df1, df2, how='outer', indicator=True)
df_new.loc[df_new['_merge'] == 'left_only'].drop('_merge', axis=1)

import collections
genome = 'aaaabbcaa'
result = collections.deque()
genome += '$'
last = genome[0]
counter = 1
for c in genome[1:]:
  if c == last:
    counter += 1
  else:
    result.append('%s%d' % (last, counter))
    last = c
    counter = 1
print(''.join(result))