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Lynn Guo's Blog – November 2014 Archive (5)

Processing Structured Text in Java–Conditional Filtering

Following problems will arise if you perform conditional filtering on text files in Java alone: 

1. The text file is not a database,so it cannot be accessed by SQL. The code needs to be modified if filtering conditions are changed. Besides, if you want a flexible conditional filtering as that in SQL, you have to self-program the dynamic expression parsing and evaluating, resulting in a great amount of programming work.

2. Stepwise loading is required for the big files that…

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Added by Lynn Guo on November 23, 2014 at 6:00pm — No Comments

esProc Helps with Computation in MongoDB – Query Indexes in an Array

MongoDB can find out elements of a built-in array according to their indexes, but cannot find the indexes through the values of the elements. For example, the elements of an array are names of people stored according to their rankings. In MongoDB, names can be found according to the rankings (indexes of the array), but the values of rankings cannot be determined through names. esProc can help MongoDB in realizing this operation. The following example will teach you how it works in…

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Added by Lynn Guo on November 19, 2014 at 6:30pm — No Comments

esProc Helps Process Structured Texts in Java – Set Operations

Java doesn’t support set operations directly, so nested loops have to be used to realize the operations of intersection, union, complement and etc. between text files. If there are many text files, or the file to be computed is too big to be loaded into the memory, or it is required to perform set operations according to multiple fields, the code will become even more complicated. However, with the assistance of esProc, which supports set operations…

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Added by Lynn Guo on November 13, 2014 at 6:00pm — No Comments

esProc Helps Process Structured Texts in Java – Set Operations

Java doesn’t support set operations directly, so nested loops have to be used to realize the operations of intersection, union, complement and etc. between text files. If there are many text files, or the file to be computed is too big to be loaded into the memory, or it is required to perform set operations according to multiple fields, the code will become even more complicated. However, with the assistance of esProc, which supports set operations directly, Java can realize these…

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Added by Lynn Guo on November 11, 2014 at 12:00am — No Comments

Another way to Process structured text in java - Non-Single row records

esProc can help Java deal with various computations in processing structured texts. But in the case of non-single row records, it is necessary to preprocess the data before esProc can perform computations on it. 

Let’s look at this through an example. The text file Social.txt is the access records of a website, in which every three rows corresponds to a record. The records should be rearranged first before other computations can be performed. They should be imported in the form…

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Added by Lynn Guo on November 4, 2014 at 8:30pm — No Comments

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