3.5 mbest - Select Rows

Select records based on the specified row numbers. Note that row number starts at 0 (the first row of data starts at row 0 excluding the row of field names). Define the row numbers at from= and to= parameters (and size= parameter in some instances).

Format

mbest [s=] [from=] [to=|size=] [k=] [u=] [-r] [i=] [o=] [-nfn] [-nfno] [-x] [-q] [--help] [--version]

Parameters

`s=`	After sorted by specified field(s) (multiple fields can be specified), the rows are selected.
	`s=` parameter is required if `-q` option is not specified.
`from=`	Define the start of row number (integers greater than 0) [default value: 0]
`to=`	Define the end of row number (integers greater than 0) [default value: 0]
	Where [value of `from=` ] $\le$ [value of `to=`] .
`size=`	Number of rows to select [default value: 1]
	`to=` and `size=` cannot be specified at the same time.
`k=`	Key field (accept multiple key fields) [aggregate key break processing]
	Records with same key values will be selected based on the defined rows at `from=`,`to=`,`size=`.
	`-x`,`-nfn` options can be used to specify the field number (0〜).
`u=`	Output file of unmatched records.
	Unmatched records the do not match the criteria is written to the defined file.
`-r`	Reverse selection
	Select the rows other than the ones defined at the parameter `from=,to=(size=)`.

Example

Example 1: Basic Example

This example assumed that the "quantity" and "amount" fields are sorted from the largest value (descending order). Records are selected from the first row (line 0) by default if from=,to=,size= parameters are not specified.

$ more dat1.csv
Customer,Quantity,Amount
A,20,5200 
B,18,4000   
C,15,3500 
D,10,2000 
E,3,800 
$ mbest s=Quantity%nr,Amount%nr i=dat1.csv o=rsl1.csv
#END# kgbest i=dat1.csv o=rsl1.csv s=Quantity%nr,Amount%nr
$ more rsl1.csv
Customer,Quantity%0nr,Amount%1nr
A,20,5200

Example 2: Basic Example 2

After sorting by "customers", select 3 rows from the first row (line 0).

$ mbest s=Customer from=0 size=3 i=dat1.csv o=rsl2.csv
#END# kgbest from=0 i=dat1.csv o=rsl2.csv s=Customer size=3
$ more rsl2.csv
Customer%0,Quantity,Amount
A,20,5200 
B,18,4000   
C,15,3500

Example 3: Basic Example 3

Without sorting (in the original order), select from line 0 to line 1.

$ mbest -q from=0 to=1 i=dat1.csv o=rsl3.csv
#END# kgbest -q from=0 i=dat1.csv o=rsl3.csv to=1
$ more rsl3.csv
Customer,Quantity,Amount
A,20,5200 
B,18,4000

Example 4: Reverse Selection

Select records other than customers’ first visit to store. Save the records of customers’ first visit to the file fvd.csv.

$ more dat2.csv
Customer,Date,Amount
A,20081201,10
A,20081207,20
A,20081213,30
B,20081002,40
B,20081209,50
$ mbest s=Customer,Date k=Customer -r u=fvd.csv i=dat2.csv o=rsl4.csv
#END# kgbest -r i=dat2.csv k=Customer o=rsl4.csv s=Customer,Date u=fvd.csv
$ more rsl4.csv
Customer,Date,Amount
A,20081207,20
A,20081213,30
B,20081209,50
$ more fvd.csv
Customer,Date,Amount
A,20081201,10
B,20081002,40

Related commands

msel : The line() function can be specified in the condition parameter to carry out similar processing functions.

muniq : Returns unique values in key field.

mselnum :Select rows within a numeric range.