Эта сумма может быть рассчитана так:
df = spark.createDataFrame([
(1, "a", "xxx", None, "abc", "xyz","fgh"),
(2, "b", None, 3, "abc", "xyz","fgh"),
(3, "c", "a23", None, None, "xyz","fgh")
], ("ID","flag", "col1", "col2", "col3", "col4", "col5"))
from pyspark.sql import functions as F
from pyspark.sql.types import IntegerType
df2 = df.withColumn("sum",sum([(~F.isnull(df[col])).cast(IntegerType()) for col in df.columns]))
df2.show()
+---+----+----+----+----+----+----+---+
| ID|flag|col1|col2|col3|col4|col5|sum|
+---+----+----+----+----+----+----+---+
| 1| a| xxx|null| abc| xyz| fgh| 6|
| 2| b|null| 3| abc| xyz| fgh| 6|
| 3| c| a23|null|null| xyz| fgh| 5|
+---+----+----+----+----+----+----+---+
Надеюсь, это поможет!