On Jan 7, 5:38 am, ICBM0926 <ICBM0...@gmail.com> wrote:
> Dear all
> One may use 'axis' command to plot axes. However, one may need to use
> parameters like 'xticks' 'xminor' to acquire desired number of ticks.
> The tick label may show improper number (ex. a decimal) with these
> parameters given. Can somebody tell me how to let IDL decide tick
> label properly and automatically while It can show desired number of
> ticks?
>
> Best regards
I've had this problem many many times. You need to set several
keywords:
xrange, xtickv, xminor, and xticks
for the x axis and the corresponding y and z keywords. I'm including
a
routine that I use to make neat time tick marks. It is rather
extensive because
the user can specify if the ticks will be on year, month, day ...
boundaries.
The basic method is to determine a range (xrange) that is an multiple
of the neat
tick mark locations, then specify the number of ticks (xticks),
remembering
that xticks is the number of intervals (there is one more tick mark
than the
value of xticks). You can quit here, or continue and specify values
for the
tick valuse (xtickv) and the number of minor ticks between the major
ticks
(xminor)
;+
; NAME:
; inms_neat_ticks - determines values for tick labeling plot keywords
;
function inms_neat_ticks, anRange, $ ;; time range,
julian day
tickinterval=tickinterval, $ ;; unit of
ticks,
debug=debug
;
; ARGUMENTS:
; anRange - a two element vector containing the range of Julian
Dates
;
; KEYWORDS:
; tickinterval - specifies the tick interval to be used,
; choices are YEAR, MONTH, DAY, HOUR, QUARTER, MINUTE
; the value may be abreviated to 2 characters.
; debug - if set, diagnostic information is produced
;
; RETURN VALUE:
; A structure containing the axis formatting values
; {anRange: anAdjust, $ ;; a two element vector with the
; adjusted Julian Dates for the axis
; anTickv: anTickv, $ ;; an array tick mark locations
;
; nTicks: n_elements(anTickv)-1, $ ;; the number of tick
intervals
; nMinor: nMinor} ;; the number of minor ticks between major
;
; In the event of an error the scalar 0 is returned.
;
; EXAMPLE:
;
; The following code fragment illustrates the use of this routine
and
; inms_label_ticks.
;
; ;; convert times to Julian Dates
; ;; first PDS compiant times to UTC format
; ;; then UTC to Julian dates
; ;;
; axOrdDate = inms_doy2utc(strupcase(axHkg.sclktime))
; anJulDate = sprl_cvt_odate_jdate(axOrdDate.nDate,
axOrdDate.nMsecs)
;
; ;; determine axis formatting values
; ;; Ticks are to be on the hour
; ;;
; xTickDef = inms_neat_ticks([anJulDate[0], anJulDate[nPoints-1]],
$
; tick='Hour')
;
; ;; specify the format for the tick labels
; nDummy = inms_label_ticks(format='DOY')
;
; ;; create a plot
; ;; using the fields in the xTickDef as values for the
; ;; corresponding plot keyword
; ;;
; plot, anJulDate, anY,$
; position=anPlotPos, $
; xrange=xTickDef.anRange, $ ;; obtained from
inms_neat_ticks
; xtickv=xTickDef.anTickv, $ ;;
; xminor=xTickDef.nMinor, $ ;;
; xticks=xTickDef.nTicks, $ ;;
; xtitle='!Ctime', $
; xtickformat='inms_label_ticks', $
; yrange=[nYmin, nYmax], $
; ytitle=asLabels[anContIdx[0]], $
; _extra=extra
;
;
; CHANGES:
; 2-Jun-2005 D. Gell Initial Coding
; 16-Jun-2005 D. Gell Adjust tick mark location determination
; 17-Jun-2005 D. Gell Correct adjustment of range for even day
; increments
; 09-Nov-2005 D. Gell Added quarter hour major ticks
; 20-Sep-2006 DAG Use error handler and inms_post_message
; 02-Jan-2006 DAG Correct calculation of major ticks for quarter
hours
; 13-Mar-2008 DAG Adjust tick intervals when units are minutes
; 22-Jul-2008 DAG Adjust number of tick labels when units are
days
;-
;----------------------------------------------------------- --------------------
compile_opt logical_predicate, strictarr, hidden
;; establish error handler
;;
bDebugSw = keyword_set(debug)
nError = 0
catch, nError
if nError ne 0 then begin
catch, /cancel
inms_post_message, traceback=bDebugSw, console=inms_is_image()
or bDebugSW
if bDebugSw then stop
return, 0
endif
anMonLen = [31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
;; validate arguments
;;
if n_elements(anRange) ne 2 then begin
message, 'You must supply a two element julian time range
vector'
endif
;; decompose julian date into month, day, and year
;;
anCalRange = sprl_cvt_jdate_mdy(anRange)
anCalTimes = intarr(3, 2)
anCalTimes[0, *] = anCalRange.nYear
anCalTimes[1, *] = anCalRange.nMonth
anCalTimes[2, *] = anCalRange.nDay
case strupcase(strmid(tickinterval, 0, 2)) of
'YE': begin
;; adjusted limits start at 1 Jan of first year
;; and extend to end of 31 Dec of last year
anAdjust = julday([1, 12], [1, 31], $
anCalTimes[0, *], [0, 23], [0, 59], [0, 59])
nTickType = 1
nQuanta = 365
end
'MO': begin
;; adjusted limits begin with 1 day of first month
;; and extend through last day of last month
anAdjust = julday(anCalTimes[1, *], $
[1, anMonLen[anCalTimes[1, 1]]], anCaltimes[0, *], $
[0, 23], [0, 59], [0, 59])
ntickType = 2
nQuanta = 31
end
'DA': begin
;; adjusted limits begin at midnight of first day and
;; extend through last second of last day
anAdjust = [ulong(anRange[0]), ulong(anRange[1]+1.0)] +
0.5D00
nQuanta = 1.0
nTickType = 3
end
'HO': begin
;; adjusted limits begin at begining of first hour and
;; extend through last second of last hour
nQuanta = 1.0/2.4D01
anAdjust = ulong(24*[anRange[0], anRange[1]+nQuanta/2.]) /
2.4D01
nTicktype = 4
end
'QU': begin
;; adjusted limits begin on even quarter hour boundary
;; and extend through last quarter hour, 96 periods per
day
nQuanta = 1.0/(9.6D01)
anAdjust = ulong(96*[anRange[0], anRange[1]+nQuanta/2.]) /
9.6D01
nTickType = 6
end
'MI': begin
;; adjusted limits begin at begining of first minute and
;; extend through last second of last minute
nQuanta = 1.0/1.44d03
anAdjust = ulong(1440L*[anRange[0], $
anRange[1]+nQuanta])/1.44D03
ntickType = 5
end
else: begin
message, 'Invalid tick "'+tickinterval+'" interval
specified'
end
endcase
anAdjust = reform(anAdjust)
nInterval = anRange[1]-anRange[0]
nUnits = ceil(nInterval/nQuanta)
;; determine location of tick marks and
;; number of minor ticks on axis
;;
case nTickType of
6: begin
;; quarter hour units
case 1 of
nUnits le 4: begin
anTickv = nQuanta * dindgen(nUnits+1)+anAdjust[0]
nMinor = 0
end
nUnits le 16: begin
nMinor = 4
anTickv = 4 * nQuanta * dindgen(nUnits/4 + 1)$
+ anAdjust[0]
end
else: begin
nHours = nUnits/4
case 1 of
nHours le 6: begin
anTickv = 4*nQuanta * dindgen(nHours+1) $
+ anAdjust[0]
nMinor = 4
end
nHours le 12: begin
anTickv = 8 * nQuanta * dindgen(nHours/
2+1) $
+ anAdjust[0]
nMinor = 4
end
else: begin
anTickv = 16 * nQuanta * dindgen(nHours/
4+1) $
+ anAdjust[0]
nMinor = 4
end
endcase
end
endcase
end
5: begin
;; minute units
;;
case 1 of
nUnits le 5: begin
anTickv = nQuanta * dindgen(nUnits+1) + anAdjust
[0]
nMinor = 0
end
nUnits le 10: begin
nMinor = 2
anTickv = 2 * nQuanta * dindgen(nUnits/2 + 1)$
+ anAdjust[0]
end
nUnits le 30: begin
nMinor = 5
anTickv = 5 * nQuanta * dindgen(nUnits/5 + 1)$
+ anAdjust[0]
end
nUnits le 120: begin
nMinor = 3
anTickv = 15 * nQuanta * dindgen(nUnits/15 + 1) $
+ anAdjust[0]
end
else: begin
nMinor = 4
anTickv = 60 * nQuanta * dindgen(nUnits/60 + 1) $
+ anAdjust[0]
end
endcase
end
4: begin
;; hour units
case 1 of
nUnits le 6: begin
anTickv = nQuanta * dindgen(nUnits+1) $
+ anAdjust[0]
nMinor = 4
end
nUnits le 12: begin
anTickv = 2 * nQuanta * dindgen(nUnits/2+1) $
+ anAdjust[0]
nMinor = 4
end
nUnits le 48: begin
anTickv = 8 * nQuanta * dindgen(nUnits/8 + 1) $
+ anAdjust[0]
nMinor = 4
end
nUnits le 72: begin
anTickv = 12 * nQuanta * dindgen(nUnits/12+1) $
+ anAdjust[0]
nMinor = 6
end
else: begin
anTickv = 24 * nQuanta * dindgen(nUnits/24+1) $
+ anAdjust[0]
nMinor = 4
end
endcase
end
3: begin
;; day units
;;
case 1 of
nUnits le 5: begin
anTickv = nQuanta * dindgen(nUnits+1) + anAdjust
[0]
nMinor = 6
end
nUnits le 14: begin
anTickv = 2 * nQuanta * dindgen(nUnits/2+1) $
+ anAdjust[0]
nMinor = 4
end
nUnits le 35: begin
anTickv = 7 * nQuanta * dindgen(nUnits/7+1) $
+ anAdjust[0]
nMinor = 7
end
nUnits le 70: begin
anTickv = 14 * nQuanta * dindgen(nUnits/14+1) $
+ anAdjust[0]
nMinor = 7
end
nUnits le 280: begin
anTickv = 28 * nQuanta * dindgen(nUnits/28+1) $
+ anAdjust[0]
nMinor = 4
end
else: begin
anTickv = 56 * nQuanta * dindgen(nUnits/56+1) $
+ anAdjust[0]
nMinor = 4
end
endcase
end
2: begin
;; monthly tick marks
case 1 of
nUnits le 4: anTickv = nQuanta * dindgen(nUnits+1)
nUnits le 8: anTickv = 2 * nQuanta * dindgen(nUnits/
2+1)
nunits le 12: anTickv = 3 * nQuanta * dindgen(nUnits/
3+1)
nunits le 24: anTickv = 4 * nQuanta * dindgen(nUnits/
4+1)
nunits le 48: anTickv = 6 * nQuanta * dindgen(nUnits/
6+1)
else: anTickv = 12 * nQuanta * dindgen(nUnits/
12+1)
endcase
anTickv = anTickv + anAdjust[0]
;; convert JD to MDY, and make all day of months 1
axTickMDY = sprl_cvt_jdate_mdy(anTickv+2)
anTickv = julday(axTickMDY.nMonth, $
1, axTickMDY.nYear, $
0, 0, 0)
nMinor = 0
end
1: begin
;; annual tick marks
case 1 of
nUnits le 2: anTickv = nQuanta * dindgen(4*nUnits+5)/
4
nUnits le 4: antickv = nQuanta * dindgen(2*nUnits+3)/
2
nUnits le 5: antickv = nQuanta * dindgen(nUnits+2)
nUnits le 10: antickv = 2*nQuanta * dindgen(nunits/
2+1)
else: antickv = 5*nQuanta * dindgen(nUnits/
5+1)
endcase
anTickv = anTickv + anAdjust[0]
;; convert JD to MDY, and make all day of months 1
axTickMDY = sprl_cvt_jdate_mdy(anTickv)
anTickv = julday(axTickMDY.nMonth, $
1, axTickMDY.nYear, $
0, 0, 0)
nMinor = 0
end
endcase
return, {anRange: anAdjust, $
anTickv:anTickv, $
nTicks: n_elements(anTickv)-1, $
nMinor:nMinor}
end
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