I have a Pyspark dataframe_Old (dfo) as below:
| Id | neighbor_sid | neighbor | division |
|---|---|---|---|
| a1 | 1100 | Naalehu | Hawaii |
| a2 | 1101 | key-west-fl | Miami |
| a3 | 1102 | lubbock | Texas |
| a10 | 1202 | bay-terraces | California |
I have a Pyspark dataframe_new (dfn) as below:
| Id | neighbor_sid | neighbor | division |
|---|---|---|---|
| a1 | 1100 | Naalehu | Hawaii |
| a2 | 1111 | key-largo-fl | Miami |
| a3 | 1103 | grapevine | Texas |
| a4 | 1115 | meriden-ct | Connecticut |
| a12 | 2002 | east-louisville | Kentucky |
My objective is to find the Ids from dataframe_new in dataframe_old and replace them with the new values from dataframe_new
Final expected Pyspark dataframe updated – dataframe_old
| Id | neighbor_sid | neighbor | division |
|---|---|---|---|
| a1 | 1100 | Naalehu | Hawaii |
| a2 | 1111 | key-largo-fl | Miami |
| a3 | 1103 | grapevine | Texas |
| a4 | 1115 | meriden-ct | Connecticut |
| a10 | 1202 | bay-terraces | California |
| a12 | 2002 | east-louisville | Kentucky |
My wrong attempt at solving it as it is comparing column wise instead of row
dfO.alias('a').join(dfN.alias('b'), on=['id'], how='left')
.select(
'id',
f.when(
~f.isnull(f.col('b.id')),
f.col('b.id')
).otherwise(f.col('a.id')).alias('id'),
'b.col_3'
)
.union(dfO)
.dropDuplicates()
.sort('id')
.show()
Please help – would really appreciate any guidance!
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Answer
We can do an outer join on the id fields and then use coalesce() to prioritize the fields from dfn.
columns = ['id', 'neighbor_sid', 'neighbor', 'division']
dfo.
join(dfn, 'id', 'outer').
select(*['id'] + [func.coalesce(dfn[k], dfo[k]).alias(k) for k in columns if k != 'id']).
orderBy('id').
show()
# +---+------------+------------+-----------+
# | id|neighbor_sid| neighbor| division|
# +---+------------+------------+-----------+
# | a1| 1100| Naalehu| Hawaii|
# |a10| 1202|bay-terraces| California|
# | a2| 1111|key-largo-fl| Miami|
# | a3| 1103| grapevine| Texas|
# | a4| 1115| meriden-ct|Connecticut|
# +---+------------+------------+-----------+