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Questions tagged [sparse-columns]

11 questions
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5 answers

How can you read a CSV file in R with different number of columns

I have a sparse data set, one whose number of columns vary in length, in a csv format. Here is a sample of the file text. 12223, University 12227, bridge, Sky 12828, Sunset 13801, Ground 14853, Tranceamerica 14854, San Francisco 15595, shibuya,…
CompChemist
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Compressed Sparse Column (CSC) or Compressed Sparse Row (CSR) sparse matrix?

I have a design matrix I'm converting in a sparse matrix using the scipy module It have many rows and only few columns With this shape, is it better to use the CSC or the CSR design ? Or are they strictly equivalent for the execution speed…
Covich
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apply for sparseMatrix in R

I am wondering is there a way to perform some kind of apply function on a sparseMatrix (from Matrix package) in R to cut Columns on k equinumerous groups? And is there away to divide for groups only those elements in column that are greater than…
Marcin
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How to calculate storage space used by NULL value?

It seems to be really hard to find accurate information about this. MSDN has a article about sparse columns, and which null percentage thresholds should be considered when using them. But the facts concerning default null storage space usage seem to…
Kahn
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Cannot create a row that has sparse data of size

I have a table with one pk column (bigint), one non sparse bigint, 30 k sparse columns (20 k bit, 5 k int, 5 k nvarchar(255)) and a column set. When I try to update a nvarchar column with '.' in a row where this column contains currently null I…
Ickbinet
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Sparse columns not showing any savings

Ive ran a test comparing a table with a few sparse columns to a table with no sparse columns, and i am seeing zero space saving. I have two tables, both storing Address info mainly in varchar columns. both tables allow nulls, one has columns sparse…
wilson_smyth
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Using sparse columns to reduce repetitive data in log files

I am building an application which logs automotive performance metrics to a table consisting of 100 columns X 500,000 rows per session. Some of the columns are very repetitive (coolant temperature in whole degrees Fahrenheit). Other columns change…
Mark
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what is the risk of using sparse columns instead of normal relational tables?

I have three table that related to one table,in my new design I want to replace the relationship by using sparse columns. you Can see diagram below. I know I would have Redundancy.but i want to know what is the other risk of this way of design? by…
vesna
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MS SQL: maximum sparse column count with non-null value in a table

I'm trying to find out the space sql server 2008 allocates for sparse columns. The values documented in https://msdn.microsoft.com/en-us/library/cc280604(v=sql.100).aspx seem to be wrong. When I create a table with a bigint as pk and the rest all…
Ickbinet
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SQL Server: why 'SPARSE' does not impact for a space?

Why alter table <> alter column<> SPARSE does not have an effect in cases 1-3 but only in case 4? I.e. can we say that column can be declared as SPARSE only when creating? I have tested this code in SQL2012. -- 1 CREATE TABLE UnSparsed(ID INT…
ZedZip
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Anyway to dynamically get specific sparse columns from partial class created by ADO Entity Data Model?

I've used the Database first approach to generate classes in my MVC application. We have a lot of tables, and some of them have sparse columns (which were all stored as strings, while the table from the database will have a column called "sparse…
user2317150
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