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Description of ASCII Parameter Files

Most simple ascii data files used in the SDSS are formatted as "ASCII parameter files". Examples of this are the list of plates in DR1 (with plate number, tile number, ra center, dec center) and the list of stripe segments in DR1 (listing run, rerun, camcol, field0, nFields, etc - see this tsChunk.par example). This file format is described here.


Keyword/value pairs


mjd	51256		# MJD day number of observations
filters u g r i z



typedef struct {
   double mjd;
   double humidity;
   double pressure;
   double temperature[4];

WEATHER 52191.300 0.23 75.21 {10.4 10.7 10.6 10.7}
WEATHER 52191.310 0.24 75.26 {10.3 10.6 10.5 10.7}
WEATHER 52191.320 0.23 75.28 {10.2 10.6 10.4 10.5}
WEATHER 52191.330 0.23 75.30 {10.2 10.5 10.3 10.3}
The keyword names (mjd, humidity, etc. in the above example) are case sensitive (for the IDL format they are not case sensitive). The data model defines whether the variable with describes, for example, the camera column, is camCol, CamCol, camcol, or CAMCOL.


Standard (allowed) datatypes are:

char[N]character string of length N (N = length of longest char string to appear in table +1, must be explicitly specified)
float4-byte floating-point
double8-byte floating-point
short2-byte integers (signed short assumed)
int4-byte integers (signed int assumed)
enumenumerated types (as in the C language)

The simple data types supported are: int, short, double, float, and char. For char, you also need to specify the length (the length is ignored in the IDL format).

One dimensional fixed length arrays of the above types are supported.

For example here is a complete .par file:
typedef struct {
	float mag[5];
	char b[5][20];
	double c;
	int flags[2];



Note on charater string length in tables:





For example, if one wants to keep track of when one is starting or ending a series of runs in a table, you can define an enum such as the following at the top of the table:

# Entry written at start or end of run

typedef enum {


typedef struct {
	int run;	      # Run number
	double mjd;	      # time of START or END of run

NEWSTRUCT 712 END 51876.123

NEWSTRUCT 722 END 51879.123


Multiple Tables/Structures in a single ASCII file


Reading and Writing:

Last modified: Mon Mar 3 15:22:43 CST 2003