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tcreate tables


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SEE_ALSO

NAME

tcreate -- Create a table from ASCII files describing a table format.

USAGE

tcreate table cdfile datafile

DESCRIPTION

This task reads an ASCII file containing column descriptions for a new table. The columns are defined and the table created; data are read in from a file specified by the datafile parameter (a specified number of lines may be skipped when reading in data). There may be several lines of data per table row. Blanks and tabs are skipped. Blank lines and lines beginning with # are ignored. In-line comments using # are permitted. The lines in the input files may be up to 8195 characters long, plus one character for the carriage return. The input datafile is read free-format.

Undefined values require a place holder in the data file. The word INDEF should be used as the place holder for undefined (indefinite) numerical values, the word "no" for boolean values, and a pair of adjacent quotes ("") for undefined character strings. If a value for a character string contains one or more blanks, or the comment character (#), then the entire value must be enclosed in quotes, e.g., "R CrB".

This task can also read a file containing header parameters for the table.

If a problem occurs when reading a particular data field, the execution continues, and the table entry is marked as undefined.

PARAMETERS

table [file name]
Output file name for the table created by this task.

Note that, if table is an existing FITS file, the table that is created will be appended as a new extension to the end of the file.

cdfile = STDIN [file name]
The name of the column definition file.

The column definition file contains one line for each column to be created. Each line contains up to four values giving attributes of the particular column. Every line must have a column name; optionally, it may have a data type, display format, and units. (Embedded blanks in any of these attributes must be enclosed in quotes.) Adjacent quotes are used as place holders and let you skip an attribute while defining the next one. Column names and data types are NOT case sensitive. Neither the format nor data type may contain embedded blanks. Display formats may be of the type used by Fortran or those used by SPP. If the format is not defined, a default format will be used. The format is not used for internal representation of the data and is ignored when reading data---it is used only for display purposes, for example, by tasks such as tedit, tread, and tprint. Type "help ttools opt=sysdoc" for detailed information about print formats. Comment lines may be included in this file by beginning the line with the comment symbol (#).

The following data types are recognized by this parameter (the default data type is single-precision real):


     r - Single-precision real.
     d - Double-precision real.
     i - Integer.
     s - Short integer.
     b - Boolean.
     ch*n - Character string of maximum length n.

A column of arrays can be created by giving the array length in square brackets appended to the data type. For example, a data type of r[400] would mean that the column contains an array of 400 single-precision real numbers in each row. r[20,5,4] would also mean an array of 400 reals, but in this case a TDIMi keyword will be written (for column number i) that gives the numbers 20, 5 and 4, indicating that the array should be regarded as 3-D, with 20 elements along the most rapidly varying axis and four elements along the least rapidly varying axis. Up to seven dimensions may be specified, separated by commas. For both of these cases, the data file must contain 400 values for that column for each row; the values need not all be on the same line of the data file. Text tables and column-ordered stsdas tables cannot contain arrays; see tbltype.

If you have an existing table with columns similar to those in the table you would like to create, you can use the tlcol task to generate a file which can be edited and used as the input cdfile for tcreate. That is, the output of tlcol is exactly the format that is expected for tcreate.cdfile. The syntax is also the same as for column definitions in text tables, except for the leading "#c " in text tables.

If cdfile = "STDIN" and the input is not redirected, the task prints a prompt asking for input. Press Control-Z (or Control-D, i.e. your EOF character) to terminate the list of column definitions; note that the Control-Z must NOT occur on the same line as the last column definition.

datafile = "STDIN" [file name]
The name of the input ASCII data file.

The values in the file must be in the order of the columns as given in the column-definitions file cdfile. Undefined values should have INDEF or "" as place holders for numerical or character values, respectively. Each row for the table must begin with a new line in datafile, but there can be multiple lines in datafile for each table row (see also nlines).

If all data for a table row have been read from an input line but there are additional data on the line, or if there is a data type mismatch, the following warning will be printed: "out of synch or extra data in line <number>".

Lines in the input data file are limited to 8196 characters, including the newline at the end of each line. If a longer line is encountered, the task will stop with an error.

As with cdfile, if datafile = "STDIN" and the input is not redirected, the task prints a prompt asking for input. Enter a carriage return before ending the last line and then press Control-Z (or Control-D, i.e. EOF) to close the file.

(uparfile) [file name]
The name of the input ASCII file of header parameters. This file is optional.

Each line of this file defines one header parameter, except that blank lines and lines beginning with # will be ignored. Each line should contain three parts: keyword, datatype, and value; an optional comment may be added following the value. The keyword is a string (no embedded blanks) of up to eight characters. The datatype is a single letter (t, b, i, r, or d) that indicates the type. The value is limited to 70 characters. If the type is text (t) it may contain more than one word, but in that case it must be enclosed in quotes; otherwise, the portion of the value following the first word will be interpreted as a comment.

Note that the syntax is not the same as for header keywords in text tables. The latter uses the much more reasonable "#k keyword = value comment". The datatype shouldn't need to be specified, since keywords are stored in the table as text strings anyway; the current syntax has been retained for backward compatibility.

It is possible, though not recommended, to set uparfile = "STDIN". The problem is that it is read twice, once just to count the number of entries, and once to read the values, so you would have to type in the values twice.

(nskip = 0) [integer, min=0, max=INDEF]
Number of lines to skip at the beginning of the data file.

The tcreate task will also skip blank lines and lines beginning with #; it will therefore not usually be necessary to specify nskip, as header lines may be commented out by inserting a leading #. Note that if nskip > 0 then exactly nskip lines will be skipped, even if some of them are blank or comment lines.

(nlines = 0) [integer, min=0, max=INDEF]
The number of lines in the input data file corresponding to one row in the output table. If nlines = 0 (the default) then lines will be read from the data file until every column in the row is filled. If nlines > 0 then exactly this many lines will be read for each row; if for some rows the input data are compressed into fewer than this many lines, extra dummy lines must be included following the good data. Note that comment lines and blank lines are not counted.
(nrows = 0) [integer, min=0, max=INDEF]
The number of rows to write into the table.

If this value is zero, then the entire input data file will be read. If this value is greater than zero then no more than nrows will be written to the table, even if the data file contains enough data to fill more than nrows rows of data. For a column-ordered table (see the tbltype parameter), nrows is the number of rows that will be allocated, and the actual number in the data file may be smaller.

(hist = yes) [boolean]
Add a history record containing a creation date?

If hist = yes, a header parameter will be written to the table with the keyword HISTORY that gives the date and time that tcreate was run. This parameter is added after those that were read from the uparfile, if any.

(extrapar = 5) [integer, min=0, max=INDEF]
Extra space to be reserved for header-parameter records. This is the number of records for header parameters that will be allocated, in addition to the number needed to hold the parameters specified in the uparfile parameter file. The default is five, which means that after the table is created up to five more parameters may be added (e.g., by using the tupar task) without the table being rewritten to reallocate space.
(tbltype = "default") [string, allowed values: default | row |
column | text] Type of table to create. The default is row-ordered stsdas format. To create a FITS table, use tbltype = "default" and specify a table name (table) with filename extension ".fits", ".fit", or ".??f" (? is any single character).
(extracol = 0) [integer, min=0, max=INDEF]
Extra space to be reserved for columns in the output table. This parameter is relevant only for a row-ordered stsdas format table.

This is in addition to the number required to contain those columns described by cdfile. One unit of space is taken by each single-precision, integer, or boolean column. A double-precision column requires two units of allocated space, and a character-string column takes one unit of space for each four characters, or fraction thereof.

EXAMPLES

1. Wait for the user to type in column definitions and data, each of which will be terminated by a Control-Z (or Control-D, i.e. EOF). The prompts are printed by the tcreate task; these are the lines beginning with "Give column definitions" and "Give table data". The table will have 4 columns and 2 rows.


tt> tcreate test STDIN STDIN

Give column definitions (name, datatype, print format, units)
 ... then newline & EOF to finish.
name  ch*12
ra    d     h12.1   hours
dec   d     h12.0   degrees
mag   r     f8.2
^Z

Give table data ... then newline & EOF to finish.
nameless      3:18:47   42:24   INDEF
"SA0 123456"  19:00:06.3  -0:00:01  3.5
^Z

2. Create a table called "outfile.tab" using the columns specified in "columns.cd" and the data in "data.dat".

tt> tcreate outfile columns.cd data.dat nskip=3

"columns.cd" may contain just the following:

STARno I  i5
X	r      "F6.2"  pixels
Y	R    F6.2     "pixels"
MAG R   ""   magnitude
		SHARP	  R
				ROUND		r
STARNAME   ch*15

Note the free format of, and embedded tabs in, the column definitions file itself. The format for display of MAG is not specified, but the unit is given as magnitude, so adjacent quotes are used to mark the position where the display format is expected.

The file "data.dat" may contain (if nskip=3, nlines=2):

This is a header
      header2
       header3
 1	3.0	4.0	
           5.0	6.0	7.0 HD12345
   2 10.0 11.0 12.0 13.0
14.0 "HD 122"
3 20.0    21.0        22.0         23.0     24.0  ""
dummy line

Note the tabbed and free format of the data file and the specification of the character strings. If the character data contain embedded blanks then the whole string should be quoted, otherwise this is not necessary. The final entry is the null character string.

3. The following column definitions:

STARno	 i i6
X	 r f9.2  pixels
Y	 r f9.2  pixels
MAG	 r f9.3
SHARP	 r f9.3
ROUND	 r f9.3
STARNAME ch*15

could be used with the following data file:

     1     7.92     2.64   -3.075    0.436    0.019   XXXXXXXXXXXXXXX
     2    33.89     3.14   -1.162    0.419    0.223
     3     3.68     5.07   -2.454    0.421   -0.123   HD12345
     4    42.70     5.08   -1.285    0.445    0.195   HD 123

4. The aperture photometry file from the daophot task may have the following data:

         1     6.95     2.61   99.999   99.999   99.999   99.999 . . .
          464.618  9.71  0.52   9.999    9.999    9.999    9.999 . . .
         2   200.06     2.80   99.999   99.999   99.999   99.999
          465.180  7.79  0.16   9.999    9.999    9.999    9.999
         3   156.25     5.17   14.610   14.537   14.483   14.438
          462.206  7.26  0.37   0.013    0.014    0.015    0.016


and could have the following column-definition file:

STARno	i
X	r
Y	r
MAG1	r
MAG2	r
MAG3	r
 .
 .
 .
MAG15	r
SKYMOD	r
SKYSD	r

The following could be used as an input file to define header parameters.

comment t Created 1987 July 22
NL      i 2
NX      i 284
NY      i 492
THRESH  r 27.0
AP1     r 3.0
PH/ADU  r 20.0
RNOISE  r 6.50
BAD     r 300.0

BUGS

REFERENCES

This task was written by Phil Hodge.

SEE ALSO

Type "help ttools opt=sysdoc" for a higher-level description of the ttools package. See also the files in "tables$doc/".


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