Box the compass: Difference between revisions
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(→{{header|Python}}: Modulo already handles the negatives.) |
(→Tcl: Added implementation) |
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32 North by west 354.37° |
32 North by west 354.37° |
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1 North 354.38°</pre> |
1 North 354.38°</pre> |
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=={{header|Tcl}}== |
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<lang tcl>proc angle2compass {angle} { |
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set dirs { |
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N NbE N-NE NEbN NE NEbE E-NE EbN E EbS E-SE SEbE SE SEbS S-SE SbE |
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S SbW S-SW SWbS SW SWbW W-SW WbS W WbN W-NW NWbW NW NWbN N-NW NbW |
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} |
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set unpack {N north E east W west S south b " by "} |
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# Compute the width of each compass segment |
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set sep [expr {360.0 / [llength $dirs]}] |
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# Work out which segment contains the compass angle |
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set dir [expr {round((fmod($angle + $sep/2, 360) - $sep/2) / $sep)}] |
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# Convert to a named direction |
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return [string totitle [string map $unpack [lindex $dirs $dir]]] |
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} |
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for {set i 0} {$i < 33} {incr i} { |
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set heading [expr {$i * 11.25}] |
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if {$i % 3 == 1} {set heading [expr {$heading + 5.62}]} |
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if {$i % 3 == 2} {set heading [expr {$heading - 5.62}]} |
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set index [expr {$i % 32 + 1}] |
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puts [format "%2i %-18s %7.2f°" $index [angle2compass $heading] $heading] |
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}</lang> |
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Output: |
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<pre> |
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1 North 0.00° |
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2 North by east 16.87° |
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3 North-northeast 16.88° |
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4 Northeast by north 33.75° |
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5 Northeast 50.62° |
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6 Northeast by east 50.63° |
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7 East-northeast 67.50° |
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8 East by north 84.37° |
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9 East 84.38° |
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10 East by south 101.25° |
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11 East-southeast 118.12° |
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12 Southeast by east 118.13° |
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13 Southeast 135.00° |
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14 Southeast by south 151.87° |
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15 South-southeast 151.88° |
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16 South by east 168.75° |
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17 South 185.62° |
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18 South by west 185.63° |
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19 South-southwest 202.50° |
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20 Southwest by south 219.37° |
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21 Southwest 219.38° |
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22 Southwest by west 236.25° |
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23 West-southwest 253.12° |
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24 West by south 253.13° |
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25 West 270.00° |
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26 West by north 286.87° |
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27 West-northwest 286.88° |
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28 Northwest by west 303.75° |
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29 Northwest 320.62° |
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30 Northwest by north 320.63° |
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31 North-northwest 337.50° |
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32 North by west 354.37° |
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1 North 354.38° |
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</pre> |
Revision as of 10:06, 28 March 2011
Box the compass is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.
Avast me hearties!
There be many a land lubber that knows naught of the pirate ways and gives direction by degree! They know not how to box the compass!
Task description
- Create a function that takes a heading in degrees and returns the correct 32-point compass heading.
- Print and display a table of Index, Compass point, and Degree; rather like the corresponding columns from, the first table of the wikipedia article, but use the following 33 headings as input:
[0.0, 16.87, 16.88, 33.75, 50.62, 50.63, 67.5, 84.37, 84.38, 101.25, 118.12, 118.13, 135.0, 151.87, 151.88, 168.75, 185.62, 185.63, 202.5, 219.37, 219.38, 236.25, 253.12, 253.13, 270.0, 286.87, 286.88, 303.75, 320.62, 320.63, 337.5, 354.37, 354.38]
. (They should give the same order of points but are spread throughout the ranges of acceptance).
Note
- The headings and indices can be calculated from this pseudocode:
for i in 0..33 inclusive: heading = i * 11.25 case i %3: if 1: heading += 5.62; break if 2: heading -= 5.62; break end index = ( i mod 32) + 1
Python
<lang python>majors = 'north east south west'.split() majors = majors + majors # no need for modulo later quarter1 = 'N,N by E,N-NE,NE by N,NE,NE by E,E-NE,E by N'.split(',') quarter2 = [p.replace('NE','EN') for p in quarter1]
def degrees2compasspoint(d):
d = (d % 360) + 360/64 majorindex, minor = divmod(d, 90.) majorindex = int(majorindex) minorindex = int( (minor*4) // 45 ) p1, p2 = majors[majorindex: majorindex+2] if p1 in {'north', 'south'}: q = quarter1 else: q = quarter2 return q[minorindex].replace('N', p1).replace('E', p2).capitalize()
for i in range(33):
d = i * 11.25 m = i % 3 if m == 1: d += 5.62 elif m == 2: d -= 5.62 n = i % 32 + 1 print( '%2i %-18s %7.2f°' % (n, degrees2compasspoint(d), d) )</lang>
- Output
1 North 0.00° 2 North by east 16.87° 3 North-northeast 16.88° 4 Northeast by north 33.75° 5 Northeast 50.62° 6 Northeast by east 50.63° 7 East-northeast 67.50° 8 East by north 84.37° 9 East 84.38° 10 East by south 101.25° 11 East-southeast 118.12° 12 Southeast by east 118.13° 13 Southeast 135.00° 14 Southeast by south 151.87° 15 South-southeast 151.88° 16 South by east 168.75° 17 South 185.62° 18 South by west 185.63° 19 South-southwest 202.50° 20 Southwest by south 219.37° 21 Southwest 219.38° 22 Southwest by west 236.25° 23 West-southwest 253.12° 24 West by south 253.13° 25 West 270.00° 26 West by north 286.87° 27 West-northwest 286.88° 28 Northwest by west 303.75° 29 Northwest 320.62° 30 Northwest by north 320.63° 31 North-northwest 337.50° 32 North by west 354.37° 1 North 354.38°
Tcl
<lang tcl>proc angle2compass {angle} {
set dirs {
N NbE N-NE NEbN NE NEbE E-NE EbN E EbS E-SE SEbE SE SEbS S-SE SbE S SbW S-SW SWbS SW SWbW W-SW WbS W WbN W-NW NWbW NW NWbN N-NW NbW
} set unpack {N north E east W west S south b " by "}
# Compute the width of each compass segment set sep [expr {360.0 / [llength $dirs]}]
# Work out which segment contains the compass angle set dir [expr {round((fmod($angle + $sep/2, 360) - $sep/2) / $sep)}]
# Convert to a named direction return [string totitle [string map $unpack [lindex $dirs $dir]]]
}
for {set i 0} {$i < 33} {incr i} {
set heading [expr {$i * 11.25}] if {$i % 3 == 1} {set heading [expr {$heading + 5.62}]} if {$i % 3 == 2} {set heading [expr {$heading - 5.62}]} set index [expr {$i % 32 + 1}] puts [format "%2i %-18s %7.2f°" $index [angle2compass $heading] $heading]
}</lang> Output:
1 North 0.00° 2 North by east 16.87° 3 North-northeast 16.88° 4 Northeast by north 33.75° 5 Northeast 50.62° 6 Northeast by east 50.63° 7 East-northeast 67.50° 8 East by north 84.37° 9 East 84.38° 10 East by south 101.25° 11 East-southeast 118.12° 12 Southeast by east 118.13° 13 Southeast 135.00° 14 Southeast by south 151.87° 15 South-southeast 151.88° 16 South by east 168.75° 17 South 185.62° 18 South by west 185.63° 19 South-southwest 202.50° 20 Southwest by south 219.37° 21 Southwest 219.38° 22 Southwest by west 236.25° 23 West-southwest 253.12° 24 West by south 253.13° 25 West 270.00° 26 West by north 286.87° 27 West-northwest 286.88° 28 Northwest by west 303.75° 29 Northwest 320.62° 30 Northwest by north 320.63° 31 North-northwest 337.50° 32 North by west 354.37° 1 North 354.38°