Various routines with dealing with CSR matrices. More...
#include <GKlib.h>
Go to the source code of this file.
Macros | |
| #define | OMPMINOPS 50000 |
Detailed Description
Various routines with dealing with CSR matrices.
- Version
$Id: csr.c 13437 2013-01-11 21:54:10Z karypis $
Definition in file csr.c.
Macro Definition Documentation
Function Documentation
| void gk_csr_CompactColumns | ( | gk_csr_t * | mat | ) |
Compacts the column-space of the matrix by removing empty columns. As a result of the compaction, the column numbers are renumbered. The compaction operation is done in place and only affects the row-based representation of the matrix. The new columns are ordered in decreasing frequency.
- Parameters
-
mat the matrix whose empty columns will be removed.
Computes the similarity between two rows/columns
- Parameters
-
mat the matrix itself. The routine assumes that the indices are sorted in increasing order. i1 is the first row/column, i2 is the second row/column, what is either GK_CSR_ROW or GK_CSR_COL indicating the type of objects between the similarity will be computed, simtype is the type of similarity and is one of GK_CSR_COS, GK_CSR_JAC, GK_CSR_MIN, GK_CSR_AMIN
- Returns
- the similarity between the two rows/columns.
| gk_csr_t* gk_csr_Create | ( | ) |
| void gk_csr_Free | ( | gk_csr_t ** | mat | ) |
| void gk_csr_FreeContents | ( | gk_csr_t * | mat | ) |
| int gk_csr_GetSimilarRows | ( | gk_csr_t * | mat, |
| int | nqterms, | ||
| int * | qind, | ||
| float * | qval, | ||
| int | simtype, | ||
| int | nsim, | ||
| float | minsim, | ||
| gk_fkv_t * | hits, | ||
| int * | i_marker, | ||
| gk_fkv_t * | i_cand | ||
| ) |
Finds the n most similar rows (neighbors) to the query using cosine similarity.
- Parameters
-
mat the matrix itself nqterms is the number of columns in the query qind is the list of query columns qval is the list of correspodning query weights simtype is the type of similarity and is one of GK_CSR_COS, GK_CSR_JAC, GK_CSR_MIN, GK_CSR_AMIN nsim is the maximum number of requested most similar rows. If -1 is provided, then everything is returned unsorted. minsim is the minimum similarity of the requested most similar rows hits is the result set. This array should be at least of length nsim. i_marker is an array of size equal to the number of rows whose values are initialized to -1. If NULL is provided then this array is allocated and freed internally. i_cand is an array of size equal to the number of rows. If NULL is provided then this array is allocated and freed internally.
- Returns
- the number of identified most similar rows, which can be smaller than the requested number of nnbrs in those cases in which there are no sufficiently many neighbors.
| void gk_csr_Init | ( | gk_csr_t * | mat | ) |
Eliminates certain entries from the rows/columns of the matrix. The filtering takes place by keeping only the highest weight entries whose sum accounts for a certain fraction of the overall weight of the row/column.
- Parameters
-
mat the matrix to be prunned, what indicates if the rows (GK_CSR_ROW) or the columns (GK_CSR_COL) of the matrix will be prunned, norm indicates the norm that will be used to aggregate the weights and possible values are 1 or 2, fraction is the fraction of the overall norm that will be retained by the kept entries.
- Returns
- the filtered matrix consisting only of its row-based structure. The input matrix is not modified.
Normalizes the rows/columns of the matrix to be unit length.
- Parameters
-
mat the matrix itself, what indicates what will be normalized and is obtained by specifying GK_CSR_ROW, GK_CSR_COL, GK_CSR_ROW|GK_CSR_COL. norm indicates what norm is to normalize to, 1: 1-norm, 2: 2-norm
Prunes certain rows/columns of the matrix. The prunning takes place by analyzing the row structure of the matrix. The prunning takes place by removing rows/columns but it does not affect the numbering of the remaining rows/columns.
- Parameters
-
mat the matrix to be prunned, what indicates if the rows (GK_CSR_ROW) or the columns (GK_CSR_COL) of the matrix will be prunned, minf is the minimum number of rows (columns) that a column (row) must be present in order to be kept, maxf is the maximum number of rows (columns) that a column (row) must be present at in order to be kept.
- Returns
- the prunned matrix consisting only of its row-based structure. The input matrix is not modified.
Reads a CSR matrix from the supplied file and stores it the matrix's forward structure.
- Parameters
-
filename is the file that stores the data. format is either GK_CSR_FMT_METIS, GK_CSR_FMT_CLUTO, GK_CSR_FMT_CSR, GK_CSR_FMT_BINROW, GK_CSR_FMT_BINCOL specifying the type of the input format. The GK_CSR_FMT_CSR does not contain a header line, whereas the GK_CSR_FMT_BINROW is a binary format written by gk_csr_Write() using the same format specifier. readvals is either 1 or 0, indicating if the CSR file contains values or it does not. It only applies when GK_CSR_FMT_CSR is used. numbering is either 1 or 0, indicating if the numbering of the indices start from 1 or 0, respectively. If they start from 1, they are automatically decreamented during input so that they will start from 0. It only applies when GK_CSR_FMT_CSR is used.
- Returns
- the matrix that was read.
Splits the matrix into multiple sub-matrices based on the provided color array.
- Parameters
-
mat is the original matrix. color is an array of size equal to the number of non-zeros in the matrix (row-wise structure). The matrix is split into as many parts as the number of colors. For meaningfull results, the colors should be numbered consecutively starting from 0.
- Returns
- an array of matrices for each supplied color number.
Eliminates certain entries from the rows/columns of the matrix. The filtering takes place by keeping only the highest weight top-K entries along each row/column and those entries whose weight is greater than a specified value.
- Parameters
-
mat the matrix to be prunned, what indicates if the rows (GK_CSR_ROW) or the columns (GK_CSR_COL) of the matrix will be prunned, topk is the number of the highest weight entries to keep. keepval is the weight of a term above which will be kept. This is used to select additional terms past the first topk.
- Returns
- the filtered matrix consisting only of its row-based structure. The input matrix is not modified.
Writes the row-based structure of a matrix into a file.
- Parameters
-
mat is the matrix to be written, filename is the name of the output file. format is one of: GK_CSR_FMT_CLUTO, GK_CSR_FMT_CSR, GK_CSR_FMT_BINROW, GK_CSR_FMT_BINCOL. writevals is either 1 or 0 indicating if the values will be written or not. This is only applicable when GK_CSR_FMT_CSR is used. numbering is either 1 or 0 indicating if the internal 0-based numbering will be shifted by one or not during output. This is only applicable when GK_CSR_FMT_CSR is used.
Eliminates certain entries from the rows/columns of the matrix. The filtering takes place by keeping only the terms whose contribution to the total length of the document is greater than a user-splied multiple over the average.
This routine assumes that the vectors are normalized to be unit length.
- Parameters
-
mat the matrix to be prunned, what indicates if the rows (GK_CSR_ROW) or the columns (GK_CSR_COL) of the matrix will be prunned, zscore is the multiplicative factor over the average contribution to the length of the document.
- Returns
- the filtered matrix consisting only of its row-based structure. The input matrix is not modified.