使用纱线比较器在MapReduce Python中进行字数排序
我想解决字数问题,并希望根据文件中出现的频率以相反的顺序获得结果 以下是我为此编写的四个文件(两个映射器和两个还原器,因为一个映射还原作业无法解决此问题): 1) mapper1.py使用纱线比较器在MapReduce Python中进行字数排序,python,hadoop,mapreduce,yarn,hadoop-streaming,Python,Hadoop,Mapreduce,Yarn,Hadoop Streaming,我想解决字数问题,并希望根据文件中出现的频率以相反的顺序获得结果 以下是我为此编写的四个文件(两个映射器和两个还原器,因为一个映射还原作业无法解决此问题): 1) mapper1.py import sys import re reload(sys) sys.setdefaultencoding('utf-8') # required to convert to unicode for line in sys.stdin: try: article_id, text
import sys
import re
reload(sys)
sys.setdefaultencoding('utf-8') # required to convert to unicode
for line in sys.stdin:
try:
article_id, text = unicode(line.strip()).split('\t', 1)
except ValueError as e:
continue
words = re.split("\W*\s+\W*", text, flags=re.UNICODE)
for word in words:
print "%s\t%d" % (word.lower(), 1)
2) 减速器1.py
import sys
current_key = None
word_sum = 0
for line in sys.stdin:
try:
key, count = line.strip().split('\t', 1)
count = int(count)
except ValueError as e:
continue
if current_key != key:
if current_key:
print "%s\t%d" % (current_key, word_sum)
word_sum = 0
current_key = key
word_sum += count
if current_key:
print "%s\t%d" % (current_key, word_sum)
3) mapper2.py
import sys
import re
reload(sys)
sys.setdefaultencoding('utf-8') # required to convert to unicode
for line in sys.stdin:
try:
word, count = line.strip().split('\t', 1)
count = int(count)
except ValueError as e:
continue
print "%s\t%d" % (word, count)
4) 减速机2.py
import sys
for line in sys.stdin:
try:
word, count = line.strip().split('\t', 1)
count = int(count)
except ValueError as e:
continue
print "%s\t%d" % (word, count)
下面是我在bash环境中运行的两个thread命令
OUT_DIR="wordcount_result_1"
NUM_REDUCERS=8
hdfs dfs -rm -r -skipTrash ${OUT_DIR} > /dev/null
yarn jar /opt/cloudera/parcels/CDH/lib/hadoop-mapreduce/hadoop-streaming.jar \
-D mapred.jab.name="Streaming wordCount" \
-D mapreduce.job.reduces=${NUM_REDUCERS} \
-files mapper1.py,reducer1.py \
-mapper "python mapper1.py" \
-combiner "python reducer1.py" \
-reducer "python reducer1.py" \
-input /test/articles-part-short \
-output ${OUT_DIR} > /dev/null
OUT_DIR_2="wordcount_result_2"
NUM_REDUCERS=1
hdfs dfs -rm -r -skipTrash ${OUT_DIR_2} > /dev/null
yarn jar /opt/cloudera/parcels/CDH/lib/hadoop-mapreduce/hadoop-streaming.jar \
-D mapred.jab.name="Streaming wordCount Rating" \
-D mapreduce.job.output.key.comparator.class=org.apache.hadoop.mapreduce.lib.partition.KeyFieldBasedComparator \
-D map.output.key.field.separator=\t \
-D mapreduce.partition.keycomparator.options=-k2,2nr \
-D mapreduce.job.reduces=${NUM_REDUCERS} \
-files mapper2.py,reducer2.py \
-mapper "python mapper2.py" \
-reducer "python reducer2.py" \
-input ${OUT_DIR} \
-output ${OUT_DIR_2} > /dev/null
hdfs dfs -cat ${OUT_DIR_2}/part-00000 | head
这并没有给我正确的答案。有人能解释一下哪里出了问题吗
另一方面,
在mapper2.py
中,如果我以以下方式打印
打印“%d\t%s”%(计数,字)
在reducer2.py
中,如果我按照以下方式阅读
count,word=line.strip().split('\t',1)
并编辑第二个纱线命令选项以
-D mapreduce.partition.keycomarator.options=-k1,1nr
这给了我正确的答案
为什么它在上述两种情况下的表现都不同
有人能帮我理解Hadoop MapReduce的Comparator选项吗?这会有用的
yarn jar /opt/cloudera/parcels/CDH/lib/hadoop-mapreduce/hadoop-streaming.jar \
-D mapred.jab.name="Streaming wordCount rating" \
-D mapreduce.job.output.key.comparator.class=org.apache.hadoop.mapreduce.lib.partition.KeyFieldBasedComparator \
-D mapreduce.partition.keycomparator.options='-k2nr' \
-D stream.num.map.output.key.fields=2 \
-D mapred.map.tasks=1 \
-D mapreduce.job.reduces=1 \
-files mapper2.py,reducer2.py \
-mapper "python mapper2.py" \
-reducer "python reducer2.py" \
-input /user/jovyan/assignment0_1563877099149160 \
-output ${OUT_DIR} > /dev/null