# Copyright 2014 Cloudera Inc. # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. import csv import tempfile from posixpath import join as pjoin import ibis.common.exceptions as com import ibis.expr.schema as sch import ibis.util as util from ibis.config import options class DataFrameWriter: """ Interface class for writing pandas objects to Impala tables Class takes ownership of any temporary data written to HDFS """ def __init__(self, client, df, path=None): self.client = client self.hdfs = client.hdfs self.df = df self.temp_hdfs_dirs = [] def write_temp_csv(self): temp_hdfs_dir = pjoin( options.impala.temp_hdfs_path, 'pandas_{}'.format(util.guid()) ) self.hdfs.mkdir(temp_hdfs_dir) # Keep track of the temporary HDFS file self.temp_hdfs_dirs.append(temp_hdfs_dir) # Write the file to HDFS hdfs_path = pjoin(temp_hdfs_dir, '0.csv') self.write_csv(hdfs_path) return temp_hdfs_dir def write_csv(self, path): with tempfile.NamedTemporaryFile() as f: # Write the DataFrame to the temporary file path if options.verbose: util.log( 'Writing DataFrame to temporary file {}'.format(f.name) ) self.df.to_csv( f.name, header=False, index=False, sep=',', quoting=csv.QUOTE_NONE, escapechar='\\', na_rep='#NULL', ) f.seek(0) if options.verbose: util.log('Writing CSV to: {0}'.format(path)) self.hdfs.put(path, f.name) return path def get_schema(self): # define a temporary table using delimited data return sch.infer(self.df) def delimited_table(self, csv_dir, name=None, database=None): temp_delimited_name = 'ibis_tmp_pandas_{0}'.format(util.guid()) schema = self.get_schema() return self.client.delimited_file( csv_dir, schema, name=temp_delimited_name, database=database, delimiter=',', na_rep='#NULL', escapechar='\\\\', external=True, persist=False, ) def __del__(self): try: self.cleanup() except com.IbisError: pass def cleanup(self): for path in self.temp_hdfs_dirs: self.hdfs.rmdir(path) self.temp_hdfs_dirs = [] self.csv_dir = None def write_temp_dataframe(client, df): writer = DataFrameWriter(client, df) path = writer.write_temp_csv() return writer, writer.delimited_table(path)