Questions tagged [big-data]

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45 views

Learning a perceptron from stream data

I want to train a Perceptron using stochastic gradient rulefrom the stream data. I have very limited amount of memory and i can store only $N$ examples. Suppose my population consist of point as ...
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1answer
242 views

Large-scale string clustering

I've more than 10 million strings of length 1-100 characters. This number will be even bigger in the future. I'm interested in clustering this data, but I'm not quite sure what would be effective at ...
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0answers
23 views

Clarification on MapReduce description in textbook

I am reading through chapter 2 of of the free textbook "Mining of Massive Datasets" (http://www.mmds.org/). On page 28 the following is stated: "It is reasonable to create one Map task for every ...
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0answers
22 views

Locality sensitive hashing with non-scalal values

Locality sensitive hashing works well when matching is between vectors of scalars, but I now need to extend LSH to compare matrices. Each matrix is formed of n readings from m sensors forming a n by m ...
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1answer
80 views

Where do you exactly use data structures?

I know what data structures is, How it works & importance of it. I just have some doubts on where do we actually use it. When database can do filtering, fetching, sorting efficiently, Why we ...
0
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1answer
86 views

Bias or not when finding patterns using data mining techniques?

I am currently following a course on Data Mining and i am very curious about the deeper underlying method. As far as i have learned so far data mining is about finding unknown patterns that can be ...
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1answer
43 views

Number of seeks in an I/O efficent algroithm

A seek is the task of positioning the read/write head of the disk to the required data block, and irrespective of the size of the data block, all contiguous data can be accessed using a single seek. ...
1
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1answer
34 views

Why splitted text files is bigger than a large one with the same content?

I have this large text file that when unzipped has about 2GB. I split this one into multiple(more than 5 million) files and now I have a folder of about 20GB, how is this possible?
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0answers
16 views

What are internal clustering index for binary data ? And if possible applicable to massive cluster ?

I was wondering what are the current existing internal clustering index for binary data. I know already the silhouette and Davis Bouldin for euclidian space, i suppose they work as well in binary ...
1
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1answer
63 views

Taking intersection in large search

As I understand, you can build the the word -> pages index in Google or large SQL database since indexed search has complexity O(1) -- lookup gives you a billion-page result at once ...
2
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1answer
580 views

(a,b)-tree vs B-tree

I would like to know what are the differences between (a,b)-tree and a B-tree. It has been a few days I am studying different papers and I am seeing different definitions that make me confused. For ...
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0answers
526 views

Examples of real world graphs that are too big for a single commodity-type machine

I've been reading on distributed systems for processing on large graphs. The most prominent examples include Pregel (developed by Google) and Apache Giraph. Most of these systems argue their existence ...
2
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2answers
240 views

Hashing by doing modulo $m$ for $m=p^2$ for a prime $p$ instead of using a prime $m$ - is it that bad?

I am doing an exercise from a Big Data course I'm taking on Coursera (this exercise is for experimenting with a big-data problem and is not for any credit or homework) , the assignment was described ...
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4answers
606 views

High Dimensional Data Structures

I have a 20-dimensional dataset, with a large amount of data points. I would like to have each dimension discretized into bins. Per bin, I would like to be able to access two neighbours per dimension (...
2
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0answers
762 views

Looking for dynamic network data sets [closed]

There are a number of collections of network (or graph) data sets freely available on the web, e.g. http://snap.stanford.edu/data/index.html http://www.cc.gatech.edu/dimacs10/downloads.shtml I am ...
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4answers
2k views

If I have a large random array of 0s and 1s that I want to sort what kind of an algorithm and data structures should I consider?

What are the types of things that need to be considered if I need to sort a large random array of 0s and 1s? You can assume large array is in the order of million or billions. I understand there ...
3
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2answers
2k views

Bloom Filter for 208 million URLs

I need to create a bloom filter of 208 million URLs. What would be a good choice of bit vector size and number of hash functions? I tried a bit vector of size 1 GB and 4 hash functions, but it ...
8
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4answers
338 views

Applying algorithms on large data

Is there any book or tutorial that teaches us how to efficiently apply the common algorithms (sorting, searching, etc.) on large data (i.e. data that cannot be fully loaded into main memory) and how ...