I have a dataframe in Pyspark with a date column called "report_date".
I want to create a new column called "report_date_10" that is 10 days added to the original report_date column.
Below is the code I tried:
df_dc["report_date_10"] = df_dc["report_date"] + timedelta(days=10)
This is the error I got:
AttributeError: 'datetime.timedelta' object has no attribute '_get_object_id'
Help! thx
It seems you are using the pandas syntax for adding a column; For spark, you need to use withColumn to add a new column; For adding the date, there's the built in date_add function:
import pyspark.sql.functions as F
df_dc = spark.createDataFrame([['2018-05-30']], ['report_date'])
df_dc.withColumn('report_date_10', F.date_add(df_dc['report_date'], 10)).show()
+-----------+--------------+
|report_date|report_date_10|
+-----------+--------------+
| 2018-05-30| 2018-06-09|
+-----------+--------------+
Related
I received help with following PySpark to prevent errors when doing a Merge in Databricks, see here
Databricks Error: Cannot perform Merge as multiple source rows matched and attempted to modify the same target row in the Delta table conflicting way
I was wondering if I could get help to modify the code to drop NULLs.
from pyspark.sql.window import Window
from pyspark.sql.functions import row_number
df2 = partdf.withColumn("rn", row_number().over(Window.partitionBy("P_key").orderBy("Id")))
df3 = df2.filter("rn = 1").drop("rn")
Thanks
The code that you are using does not completely delete the rows where P_key is null. It is applying the row number for null values and where row number value is 1 where P_key is null, that row is not getting deleted.
You can instead use the df.na.drop instead to get the required result.
df.na.drop(subset=["P_key"]).show(truncate=False)
To make your approach work, you can use the following approach. Add a row with least possible unique id value. Store this id in a variable, use the same code and add additional condition in filter as shown below.
from pyspark.sql.window import Window
from pyspark.sql.functions import row_number,when,col
df = spark.read.option("header",True).csv("dbfs:/FileStore/sample1.csv")
#adding row with least possible id value.
dup_id = '0'
new_row = spark.createDataFrame([[dup_id,'','x','x']], schema = ['id','P_key','c1','c2'])
#replacing empty string with null for P_Key
new_row = new_row.withColumn('P_key',when(col('P_key')=='',None).otherwise(col('P_key')))
df = df.union(new_row) #row added
#code to remove duplicates
df2 = df.withColumn("rn", row_number().over(Window.partitionBy("P_key").orderBy("id")))
df2.show(truncate=False)
#additional condition to remove added id row.
df3 = df2.filter((df2.rn == 1) & (df2.P_key!=dup_id)).drop("rn")
df3.show()
In pyspark , i tried to do this
df = df.select(F.col("id"),
F.col("mp_code"),
F.col("mp_def"),
F.col("mp_desc"),
F.col("mp_code_desc"),
F.col("zdmtrt06_zstation").alias("station"),
F.to_timestamp(F.col("date_time"), "yyyyMMddHHmmss").alias("date_time_utc"))
df = df.groupBy("id", "mp_code", "mp_def", "mp_desc", "mp_code_desc", "station").min(F.col("date_time_utc"))
But, i have an issue
raise TypeError("Column is not iterable")
TypeError: Column is not iterable
Here is an extract of the pyspark documentation
GroupedData.min(*cols)[source]
Computes the min value for each numeric column for each group.
New in version 1.3.0.
Parameters: cols : str
In other words, the min function does not support column arguments. It only works with column names (strings) like this:
df.groupBy("x").min("date_time_utc")
# you can also specify several column names
df.groupBy("x").min("y", "z")
Note that if you want to use a column object, you have to use agg:
df.groupBy("x").agg(F.min(F.col("date_time_utc")))
I have a fixed date "2000/01/01" and a dataframe:
data1 = [{'index':1,'offset':50}]
data_p = sc.parallelize(data1)
df = spark.createDataFrame(data_p)
I want to create a new column by adding the offset column to this fixed date
I tried different method but cannot pass the column iterator and expr error as:
function is neither a registered temporary function nor a permanent function registered in the database 'default'
The only solution I can think of is
df = df.withColumn("zero",lit(datetime.strptime('2000/01/01', '%Y/%m/%d')))
df.withColumn("date_offset",expr("date_add(zero,offset)")).drop("zero")
Since I cannot use lit and datetime.strptime in the expr, I have to use this approach which creates a redundant column and redundant operations.
Any better way to do it?
As you have marked it as pyspark question so in python you can do below
df_a3.withColumn("date_offset",F.lit("2000-01-01").cast("date") + F.col("offset").cast("int")).show()
Edit- As per comment below lets assume there was an extra column of type then based on it below code can be used
df_a3.withColumn("date_offset",F.expr("case when type ='month' then add_months(cast('2000-01-01' as date),offset) else date_add(cast('2000-01-01' as date),cast(offset as int)) end ")).show()
I have a dataframe which contains months and will change quite frequently. I am saving this dataframe values as list e.g. months = ['202111', '202112', '202201']. Using a for loop to to iterate through all list elements and trying to provide dynamic column values with following code:
for i in months:
df = (
adjustment_1_prepared_df.select("product", "mnth", "col1", "col2")
.groupBy("product")
.agg(
f.min(f.when(condition, f.col("col1")).otherwise(9999999)).alias(
concat("col3_"), f.lit(i.col)
)
)
)
So basically in alias I am trying to give column name as a combination of constant (minInv_) and a variable (e.g. 202111) but I am getting error. How can I give a column name as combination of fixed string and a variable.
Thanks in advance!
.alias("col3_"+str(i.col))
I am trying to create a column within databricks using pyspark. I need to check if date column is found between two other date columns and if it is then 1 if it is not then 0. I am wanting to call this ground truth, since this will tell me if on date it's found in between the two date columns. This is what I have so far:
df = (df
.withColumn("Ground_truth_IE", when(col("ReadingDateTime").between(col("EventStartDateTime") & col("EventEndDateTime")), 1).otherwiste(0)
)
)
But I continue to get an error:
TypeError: between() missing 1 required positional argument: 'upperBound'
The between() operator in pyspark should be used like: between(lowerBound, upperBound)
df = df.withColumn("Ground_truth_IE", when(col("ReadingDateTime")\
.between(col("EventStartDateTime"),col("EventEndDateTime")), 1).otherwise(0))