How do I drop duplicates and keep the first value on pandas?

Question

I want to drop duplicates and keep the first value. The duplicates that want to be dropped is A = \'df\' .Here\'s my data

A   B   C   D   E
qw  1   3   1   1
er          


        

Answer 1

Create helper Series for distinguish consecutive values in A column and then filter by boolean indexing with inverted (~) boolean mask created by duplicated chained with another mask for compare value df:

s = df['A'].ne(df['A'].shift()).cumsum()
df = df[~((df['A'] == 'df') & (s.duplicated()))]
print (df)
     A   B   C   D   E
0   qw   1   3   1   1
1   er   2   4   2   6
2   ew   4   8  44   4
3   df  34  34  34  34
7   we   2   5   5   2
8   we   4   4   4   4
9   df  34   9  34  34
11  we   4   7   4   4
12  qw   2   2   7   2