pandas的dataframe轉spark的dataframe
from pyspark.sql import SparkSession
# 初始化spark會話
spark = SparkSession \
.builder \
.getOrCreate()
spark_df = spark.createDataFrame(pandas_df)
spark的dataframe轉pandas的dataframe
import pandas as pd
pandas_df = spark_df.toPandas()
由於pandas的方式是單機版的，即toPandas()的方式是單機版的，所以參考breeze_lsw改成分布式版本：
import pandas as pd
def _map_to_pandas(rdds):
return [pd.DataFrame(list(rdds))]
def topas(df, n_partitions=None):
if n_partitions is not None: df = df.repartition(n_partitions)
df_pand = df.rdd.mapPartitions(_map_to_pandas).collect()
df_pand = pd.concat(df_pand)
df_pand.columns = df.columns
return df_pand
pandas_df = topas(spark_df)