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courses:mapreduce-tutorial:step-31 [2012/02/06 08:28] straka |
courses:mapreduce-tutorial:step-31 [2012/02/06 08:41] straka |
===== Exercise 2 ===== | ===== Exercise 2 ===== |
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Implement an AllReduce job on ''/net/projects/hadoop/examples/inputs/numbers-small'', which computes | Implement an AllReduce job on ''/net/projects/hadoop/examples/inputs/numbers-small'', which computes median of the input data. You can use the following iterative algorithm: |
| * At the beginning, set //min<sub>1</sub>// = ''Integer.MIN_VALUE'', //max<sub>1</sub>// = ''Integer.MAX_VALUE'', //index_to_find// = number_of_input_data / 2. |
| * In step //i//, do the following: |
| - Consider only input keys in range <//min<sub>i</sub>//, //max<sub>i</sub>//>. |
| - Compute //split// = ceiling of mean of the keys. |
| - If the //index_to_find// is in range <1+number of keys less than //split//, number of keys less or equal to //split//>, then ''split'' is median. |
| - Else, if //index_to_find// is at most the number of keys less than //split//, set //max<sub>i+1</sub>// = //split//-1. |
| - Else, set //min<sub>i+1</sub>// = //split//+1 and subtract from //index_to_find// the number of keys less or equal to //split//. |
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You can download the template {{:courses:mapreduce-tutorial:step-31-exercise2.txt|Median.java}} and execute it using: | You can download the template {{:courses:mapreduce-tutorial:step-31-exercise2.txt|Median.java}} and execute it using: |
Implement an AllReduce job on ''/net/projects/hadoop/examples/inputs/numbers-small'', which computes | Implement an AllReduce job on ''/net/projects/hadoop/examples/inputs/numbers-small'', which computes |
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You can download the template {{:courses:mapreduce-tutorial:step-31-exercise3.txt|Median.java}} and execute it using: | You can download the template {{:courses:mapreduce-tutorial:step-31-exercise3.txt|KMeans.java}} and execute it using: |
wget --no-check-certificate 'https://wiki.ufal.ms.mff.cuni.cz/_media/courses:mapreduce-tutorial:step-31-exercise3.txt' -O KMeans.java.java | wget --no-check-certificate 'https://wiki.ufal.ms.mff.cuni.cz/_media/courses:mapreduce-tutorial:step-31-exercise3.txt' -O KMeans.java.java |
# NOW VIEW THE FILE | # NOW VIEW THE FILE |