是否有一种简单的方法可以在pyspark中删除巨大数据集(300+ col> 100k行)的空列?例如Python中的df.dropna(axis=1,how='all')
是,您可以简单地使用:
import pyspark.sql.functions as F
# Sample data
df = pd.DataFrame({'x1': ['a', '1', '2'],
'x2': ['b', None, '2'],
'x3': ['c', '0', '3'] })
df = sqlContext.createDataFrame(df)
df.show()
def drop_null_columns(df):
"""
This function drops all columns which contain null values.
:param df: A PySpark DataFrame
"""
null_counts = df.select([F.count(F.when(F.col(c).isNull(), c)).alias(c) for c in df.columns]).collect()[0].asDict()
to_drop = [k for k, v in null_counts.items() if v > 0]
df = df.drop(*to_drop)
return df
# Drops column b2, because it contains null values
drop_null_columns(df).show()
+---+---+
| x1| x3|
+---+---+
| a| c|
| 1| 0|
| 2| 3|
+---+---+
x2列已删除