If Row In Dataframe Starts With Keyword, Concat It With The Row Above

I have a question similar to here but I have not been able to break through it. I have a DataFrame structured like this: 0 inner join xx 1 on xx 2 and xx 3 and yy 4 and aa 5 inner

Solution 1:

You can use groupby+apply:

(df.groupby((~df['join'].str.startswith('and ')).cumsum())
   ['join'].apply(' '.join)
)

output:

join
1                 inner join xx
2    on xx and xx and yy and aa
3                 inner join zz
Name: join, dtype: object

Solution 2:

You can solve this using a simple for loop:

result = []
for j in df['join']:
    if j.startswith('and') and len(result) > 0:
        result[-1] += ' ' + j
    else:
        result.append(j)