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Add explanation for split=100

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This commit is contained in:
Jennifer Liu 2018-07-11 15:50:28 -07:00
parent 5021441d86
commit 612b346ed5
3 changed files with 6 additions and 3 deletions
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2
lib/dictBuilder/zdict.h
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@ -86,7 +86,7 @@ typedef struct {
unsigned d; /* dmer size : constraint: 0 < d <= k : Reasonable range [6, 16] */
unsigned steps; /* Number of steps : Only used for optimization : 0 means default (32) : Higher means more parameters checked */
unsigned nbThreads; /* Number of threads : constraint: 0 < nbThreads : 1 means single-threaded : Only used for optimization : Ignored if ZSTD_MULTITHREAD is not defined */
double splitPoint; /* Percentage of samples used for training: the first nbSamples * splitPoint samples will be used to training, 0 means default (1.0) */
double splitPoint; /* Percentage of samples used for training: the first nbSamples * splitPoint samples will be used to training, the last nbSamples * (1 - splitPoint) samples will be used for testing, 0 means default (1.0), 1.0 when all samples are used for both training and testing */
ZDICT_params_t zParams;
} ZDICT_cover_params_t;

3
programs/zstd.1
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@ -218,7 +218,8 @@ A dictionary ID is a locally unique ID that a decoder can use to verify it is us
.
.TP
\fB\-\-train\-cover[=k#,d=#,steps=#,split=#]\fR
Select parameters for the default dictionary builder algorithm named cover\. If \fId\fR is not specified, then it tries \fId\fR = 6 and \fId\fR = 8\. If \fIk\fR is not specified, then it tries \fIsteps\fR values in the range [50, 2000]\. If \fIsteps\fR is not specified, then the default value of 40 is used\. If \fIsplit\fR is not specified or \fIsplit\fR <= 0 or \fIsplit\fR > 100, then the default value of 100 is used\. Requires that \fId\fR <= \fIk\fR\.
Select parameters for the default dictionary builder algorithm named cover\. If \fId\fR is not specified, then it tries \fId\fR = 6 and \fId\fR = 8\. If \fIk\fR is not specified, then it tries \fIsteps\fR values in the range [50, 2000]\. If \fIsteps\fR is not specified, then the default value of 40 is used\. If \fIsplit\fR is not specified or \fIsplit\fR <= 0, then the default value of 100 is used\. If \fIsplit\fR is 100, all input samples are used for both training and testing
to find optimal _d_ and _k_ to build dictionary.Requires that \fId\fR <= \fIk\fR\.
.
.IP
Selects segments of size \fIk\fR with highest score to put in the dictionary\. The score of a segment is computed by the sum of the frequencies of all the subsegments of size \fId\fR\. Generally \fId\fR should be in the range [6, 8], occasionally up to 16, but the algorithm will run faster with d <= \fI8\fR\. Good values for \fIk\fR vary widely based on the input data, but a safe range is [2 * \fId\fR, 2000]\. Supports multithreading if \fBzstd\fR is compiled with threading support\.

4
programs/zstd.1.md
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@ -228,7 +228,7 @@ Compression of small files similar to the sample set will be greatly improved.
If _d_ is not specified, then it tries _d_ = 6 and _d_ = 8.
If _k_ is not specified, then it tries _steps_ values in the range [50, 2000].
If _steps_ is not specified, then the default value of 40 is used.
If _split_ is not specified or split <= 0 or split > 100, then the default value of 100 is used.
If _split_ is not specified or split <= 0, then the default value of 100 is used.
Requires that _d_ <= _k_.
Selects segments of size _k_ with highest score to put in the dictionary.
@ -238,6 +238,8 @@ Compression of small files similar to the sample set will be greatly improved.
algorithm will run faster with d <= _8_.
Good values for _k_ vary widely based on the input data, but a safe range is
[2 * _d_, 2000].
If _split_ is 100, all input samples are used for both training and testing
to find optimal _d_ and _k_ to build dictionary.
Supports multithreading if `zstd` is compiled with threading support.
Examples: