create

Purpose

Creates and opens a GAUSS dataset for subsequent writing.

Format

create [[vflag]][[-w32]][[complex]] fh=filename with vnames, col, dtyp, vtyp
Parameters:

  • vflag (literal) –

    version flag.

    -v89

    obsoleted, use -v96.

    -v92

    obsoleted, use-v96.

    -v96

    supported on all platforms.

    For details on the various versions, see Foreign Language Interface Chapter. The default format can be specified in gauss.cfg by setting the dat_fmt_version configuration variable. The default, v96, should be used.

  • filename (literal or ^string) – filename is the name to be given to the file on the disk. The name can include a path if the directory to be used is not the current directory. This file will automatically be given the extension .dat. If an extension is specified, the .dat will be overridden. If the name of the file is to be taken from a string variable, the name of the string must be preceded by the ^ (caret) operator.

  • vnames (literal or ^string or ^character matrix) – controls the names to be given to the columns of the data file. If the names are to be taken from a string or character matrix, the ^ (caret) operator must be placed before the name of the string or character matrix. The number of columns parameter, col, also has an effect on the way the names will be created. See below and see the examples for details on the ways names are assigned to a data file.

  • col (scalar expression) – scalar expression containing the number of columns in the data file. If col is 0, the number of columns will be controlled by the contents of vnames. If col is positive, the file will contain col columns and the names to be given each column will be created as necessary depending on the vnames parameter. See the examples.

  • dtyp (scalar) –

    the precision used to store the data. This is a scalar expression containing 2, 4, or 8, which is the number of bytes per element.

    2

    signed integer

    4

    single precision

    8

    double precision

    Data Type

    Digits

    Range

    integer

    4

    \(-32768 < X < 32768\)

    single

    6-7

    \(43x10^{-37} < |X| < 3.37x10^{+38}\)

    double

    15-16

    \(19x10^{-307} < |X| < 1.67x10^{-308}\)

    If the integer type is specified, numbers will be rounded to the nearest integer as they are written to the dataset. If the data to be written to thefile contains character data, the precision must be 8 or the character information will be lost.

  • vtyp (matrix) – types of variables. The types of the variables in the dataset. If rows(vtyp) * cols(vtyp) < col, only the first element is used. Otherwise nonzero elements indicate a numeric variable and zero elements indicate character variables.

Returns:

fh (scalar) – the file handle which will be used by most commands to refer to the file within GAUSS. This file handle is actually a scalar containing an integer value that uniquely identifies each file. This value is assigned by GAUSS when the create (or open) command is executed.

create [[vflag]][[-w32]][[complex]] fh=filename using comfile
Parameters:

  • vflag (literal) –

    version flag.

    -v89

    obsoleted, use -v96.

    -v92

    obsoleted, use-v96.

    -v96

    supported on all platforms.

    For details on the various versions, see Foreign Language Interface Chapter. The default format can be specified in gauss.cfg by setting the dat_fmt_version configuration variable. The default, v96, should be used.

  • filename (literal or ^string) – filename is the name to be given to the file on the disk. The name can include a path if the directory to be used is not the current directory. This file will automatically be given the extension .dat. If an extension is specified, the .dat will be overridden. If the name of the file is to be taken from a string variable, the name of the string must be preceded by the ^ (caret) operator.

  • comfile (literal or ^string) –

    the name of a command file that contains the information needed to create the file. The default extension for the command file is .gcf, which can be overridden. There are three possible commands in this file:

    numvar  n str;
outvar  varlist;
outtyp  dtyp;

    numvar and outvar are alternate ways of specifying the number and names of the variables in the dataset to be created.

    When numvar is used, n is a constant which specifies the number of variables (columns) in the data file and str is a string literal specifying the prefix to be given to all the variables. Thus:

    numvar 10 xx;

    says that there are 10 variables and that they are to be named xx01 through xx10. The numeric part of the names will be padded on the left with zeros as necessary so the names will sort correctly:

    xx1 … xx9

    1-9 names

    xx01 … xx10

    10-99 names

    xx001 … xx100

    100-999 names

    xx0001 … xx1000

    1000-8100 names

    If str is omitted, the variable prefix will be “X”. When outvar is used, varlist is a list of variable names, separated by spaces or commas. For instance: outvar x1, x2, zed; specifies that there are to be 3 variables per row of the dataset, and that they are to be named X1, X2, ZED, in that order.outtyp specifies the precision. It can be a constant: 2, 4, or 8, or it can be a literal: I, F, or D. For an explanation of the available data types, see dtyp in create... with... previously. The outtyp statement does not have to be included. If it is not, then all data will be stored in 4 bytes as single precision floating point numbers.

Returns:

fh (scalar) – the file handle which will be used by most commands to refer to the file within GAUSS. This file handle is actually a scalar containing an integer value that uniquely identifies each file. This value is assigned by GAUSS when the create (or open) command is executed.

Examples

vnames = { age, sex, educat, wage, occ };
create f1 = simdat with ^vnames,0,8;

obs = 0;
nr = 1000;

do while obs < 10000;
   data = rndn(nr, colsf(f1));

   if writer(f1,data) /= nr;
      print "Disk Full";
      end;

   endif;
   obs = obs + nr;

endo;

closeall f1;

This example uses create... with... to create a double precision data file called simdat.dat on the default drive with 5 columns. The writer() command is used to write 10000 rows of Normal random numbers into the file. The variables (columns) will be named: AGE, SEX, EDUCAT, WAGE, OCC.

Here are some examples of the variable names that will result when using a character vector of names in the argument to the create function.

vnames = { AGE PAY SEX JOB };
typ = { 1, 1, 0, 0 };
create fp = mydata with ^vnames,0,8,typ;

The names in the this example will be: AGE, PAY, SEX, JOB.

AGE and PAY are numeric variables, SEX and JOB are character variables.

create fp = mydata with ^vnames,3,2;

The names will be: AGE, PAY, SEX.

create fp = mydata with ^vnames,8,2;

The names will now be: AGE, PAY, SEX, JOB1, JOB2, JOB3, JOB4, JOB5.

If a literal is used for the vnames parameter, the number of columns should be explicitly given in the col parameter and the names will be created as follows:

create fp = mydata with var,4,2;

Giving the names: VAR1, VAR2, VAR3, VAR4.

The next example assumes a command file called comd.gcf containing the following lines, created using a text editor:

outvar age, pay, sex;
outtyp i;

Then the following program could be used to write 100 rows of random integers into a file called smpl.dat in the subdirectory called /gauss/data:

filename = "/gauss/data/smpl";
create fh = ^filename using comd;
x = rndn(100,3)*10;
if writer(fh,x) /= rows(x);
  print "Disk Full";
  end;
endif;
closeall fh;

For platforms using the backslash as a path separator, remember that two backslashes (‘’\\’’) are required to enter one backslash inside of double quotes. This is because a backslash is the escape character used to embed special characters in strings.

Remarks

If the complex flag is included, the new dataset will be initialized to store complex number data. Complex data is stored a row at a time, with the real and imaginary halves interleaved, element by element.

The -w32 flag is an optimization for Windows. It is ignored on all other platforms. GAUSS 7.0 and later use Windows system file write commands that support 64-bit file sizes. These commands are slower on Windows XP than the 32-bit file write commands that were used in GAUSS 6.0 and earlier. If you include the -w32 flag, successive writes to the file indicated by fh will use 32-bit Windows write commands, which will be faster on Windows XP. Note, however, that the -w32 flag does not support 64-bit file sizes.

See also

Functions datacreate(), datacreatecomplex(), open, readr(), writer(), eof(), close, output, iscplxf()

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