Format specification for axis values
If no Format value is set for a Frame axis, a default value is supplied instead. This is based on the value of the Digits, or Digits(axis), attribute and is chosen so that it displays the requested number of digits of precision.
"
printf"
function (e.g.
"
%1.7G"
) in order to format a single coordinate value (supplied as a double precision
number). "
SkyFrame Formats"
section. "
TimeFrame Formats"
section. When specifying this attribute by name, it should be subscripted with the number of the Frame axis to which it applies.
"
+"
:
Indicates that a plus sign should be prefixed to positive values. By default, no plus sign is
used.
"
z"
: Indicates that leading zeros should be prefixed to the value so that the first field is of constant
width, as would be required in a fixed-width table (leading zeros are always prefixed to any fields that
follow). By default, no leading zeros are added.
"
i"
: Use the standard ISO field separator (a colon) between fields. This is the default behaviour.
"
b"
: Use a blank to separate fields.
"
l"
: Use a letter ("
h"
/"
d"
, "
m"
or "
s"
as appropriate) to separate fields.
"
g"
: Use a letter and symbols to separate fields ("
h"
/"
d"
, "
m"
or "
s"
, etc, as appropriate), but
include escape sequences in the formatted value so that the Plot class will draw the separators as
small super-scripts.
"
d"
: Include a degrees field. Expressing the angle purely in degrees is also the default if none of "
h"
,
"
m"
, "
s"
or "
t"
are given.
"
h"
: Express the angle as a time and include an hours field (where 24 hours correspond to 360
degrees). Expressing the angle purely in hours is also the default if "
t"
is given without either "
m"
or
"
s"
.
"
m"
: Include a minutes field. By default this is not included.
"
s"
: Include a seconds field. By default this is not included. This request is ignored if "
d"
or "
h"
is
given, unless a minutes field is also included.
"
t"
: Express the angle as a time (where 24 hours correspond to 360 degrees). This option is ignored if
either "
d"
or "
h"
is given and is intended for use where the value is to be expressed purely in
minutes and/or seconds of time (with no hours field). If "
t"
is given without "
d"
, "
h"
, "
m"
or "
s"
being present, then it is equivalent to "
h"
.
"
."
: Indicates that decimal places are to be given for the final field in the formatted string (whichever
field this is). The "
."
should be followed immediately by an unsigned integer which gives the number
of decimal places required, or by an asterisk. If an asterisk is supplied, a default number of decimal
places is used which is based on the value of the Digits attribute.
All of the above format specifiers are case-insensitive. If several characters make conflicting requests
(e.g. if both "
i"
and "
b"
appear), then the character occurring last takes precedence, except that "
d"
and "
h"
always override "
t"
.
If the format string starts with a percentage sign (%), then the whole format string is assumed to conform to the syntax defined by the Frame class, and the axis values is formated as a decimal radians value.
"
printf"
format string), or the
extended "
iso"
syntax described below (the default value is inherited from the Frame
class):
C "
printf"
syntax: If the Format string is a C "
printf"
format description such as "
%1.7G"
, the
TimeFrame axis value will be formatted without change as a floating point value using this
format. The formatted string will thus represent an offset from the zero point specified by the
TimeFrame’
s TimeOrigin attribute, measured in units given by the TimeFrame’
s Unit
attribute.
"
iso"
syntax: This is used to format a TimeFrame axis value as a Gregorian date followed by
an optional time of day. If the Format value commences with the string "
iso"
then the
TimeFrame axis value will be converted to an absolute MJD, including the addition of
the current TimeOrigin value, and then formatted as a Gregorian date using the format "
yyyy-mm-dd"
. Optionally, the Format value may include an integer precision following
the "
iso"
specification (e.g. "
iso.2"
), in which case the time of day will be appended to
the formatted date (if no time of day is included, the date field is rounded to the nearest
day). The integer value in the Format string indicates the number of decimal places to
use in the seconds field. For instance, a Format value of "
iso.0"
produces a time of day
of the form "
hh:mm:ss"
, and a Format value of "
iso.2"
produces a time of day of the
form "
hh:mm:ss.ss"
. The date and time fields will be separated by a space unless ’
T’
is appended to the end of string, in which case the letter T (upper case) will be used as
the separator. The value of the Digits attribute is ignored when using this "
iso"
format.