4 \sectionauthor{J\"org Lehmann
}{joergl@users.sourceforge.net
}
8 With the
\verb|unit| module
\PyX{} makes available classes and
9 functions for the specification and manipulation of lengths. As usual,
10 lengths consist of a number together with a measurement unit, e.g.,
11 1 cm,
50 points,
0.42 inch. In addition,
12 lengths in
\PyX{} are composed of the five types ``true'', ``user'',
13 ``visual'', ``width'', and ``
\TeX'', e.g.,
1 user cm,
14 50 true points,
0.42 visual +
0.2 width inch. As their names
15 indicate, they serve different purposes. True lengths are not scalable
16 and are mainly used for return values of
\PyX{} functions. The other
17 length types can be rescaled by the user and differ with respect to
18 the type of object they are applied to:
21 \item[user length:
] used for lengths of graphical objects like
23 \item[visual length:
] used for sizes of visual elements, like arrows,
24 graph symbols, axis ticks, etc.
25 \item[width length:
] used for line widths
26 \item[\TeX{} length:
] used for all
\TeX{} and
\LaTeX{} output
29 When not specified otherwise, all types of lengths are interpreted
30 in terms of a default unit, which, by default, is
1 cm.
31 You may change this default unit by using the module level function
32 \begin{funcdesc
}{set
}{uscale=None, vscale=None, wscale=None,
33 xscale=None, defaultunit=None
}
34 When
\var{uscale
},
\var{vscale
},
\var{wscale
}, or
\var{xscale
} is not
35 \keyword{None
}, the corresponding scaling factor(s) is redefined to
36 the given number. When
\var{defaultunit
} is not
\keyword{None
},
37 the default unit is set to the given value, which has to be
38 one of
\code{"cm"
},
\code{"mm"
},
\code{"inch"
}, or
\code{"pt"
}.
41 For instance, if you only want thicker lines for a publication
42 version of your figure, you can just rescale all width lengths using
46 Or suppose, you are used to specify length in imperial units. In this,
47 admittedly rather unfortunate case, just use
49 unit.set(defaultunit="inch")
51 at the beginning of your program.
53 \section{Class length
}
55 \begin{classdesc
}{length
}{f, type="u", unit=None
}
56 The constructor of the
\class{length
} class expects as its first
57 argument a number
\var{f
}, which represents the prefactor of the given length.
58 By default this length is interpreted as a user length (
\code{type="u"
}) in units
59 of the current default unit (see
\function{set()
} function of the
\module{unit
}
60 module). Optionally, a different
\var{type
} may be specified, namely
61 \code{"u"
} for user lengths,
\code{"v"
} for visual lengths,
\code{"w"
}
62 for width lengths,
\code{"x"
} for
\TeX{} length, and
\code{"t"
} for true
63 lengths. Furthermore, a different unit may be specified using the
\var{unit
}
64 argument. Allowed values are
\code{"cm"
},
\code{"mm"
},
\code{"inch"
},
68 Instances of the
\class{length
} class support addition and substraction either by another
\class{length
}
69 or by a number which is then interpeted as being a user length in
70 default units, multiplication by a number and division either by another
71 \class{length
} in which case a float is returned or by a number in which
72 case a
\class{length
} instance is returned. When two lengths are
73 compared, they are first converted to meters (using the currently set
74 scaling), and then the resulting values are compared.
76 \section{Predefined length instances
}
78 A number of
\verb|length| instances are already predefined, which
79 only differ in there values for
\verb|type| and
\verb|unit|. They are
80 summarized in the following table
83 \begin{tableiii
}{lll
}{textrm
}{name
}{type
}{unit
}
84 \lineiii{\constant{m
}}{user
}{m
}
85 \lineiii{\constant{cm
}}{user
}{cm
}
86 \lineiii{\constant{mm
}}{user
}{mm
}
87 \lineiii{\constant{inch
}}{user
}{inch
}
88 \lineiii{\constant{pt
}}{user
}{points
}
89 \lineiii{\constant{t
\_m}}{true
}{m
}
90 \lineiii{\constant{t
\_cm}}{true
}{cm
}
91 \lineiii{\constant{t
\_mm}}{true
}{mm
}
92 \lineiii{\constant{t
\_inch}}{true
}{inch
}
93 \lineiii{\constant{t
\_pt}}{true
}{points
}
94 \lineiii{\constant{u
\_m}}{user
}{m
}
95 \lineiii{\constant{u
\_cm}}{user
}{cm
}
96 \lineiii{\constant{u
\_mm}}{user
}{mm
}
97 \lineiii{\constant{u
\_inch}}{user
}{inch
}
98 \lineiii{\constant{u
\_pt}}{user
}{points
}
99 \lineiii{\constant{v
\_m}}{visual
}{m
}
100 \lineiii{\constant{v
\_cm}}{visual
}{cm
}
101 \lineiii{\constant{v
\_mm}}{visual
}{mm
}
102 \lineiii{\constant{v
\_inch}}{visual
}{inch
}
103 \lineiii{\constant{v
\_pt}}{visual
}{points
}
104 \lineiii{\constant{w
\_m}}{width
}{m
}
105 \lineiii{\constant{w
\_cm}}{width
}{cm
}
106 \lineiii{\constant{w
\_mm}}{width
}{mm
}
107 \lineiii{\constant{w
\_inch}}{width
}{inch
}
108 \lineiii{\constant{w
\_pt}}{width
}{points
}
109 \lineiii{\constant{x
\_m}}{\TeX}{m
}
110 \lineiii{\constant{x
\_cm}}{\TeX}{cm
}
111 \lineiii{\constant{x
\_mm}}{\TeX}{mm
}
112 \lineiii{\constant{x
\_inch}}{\TeX}{inch
}
113 \lineiii{\constant{x
\_pt}}{\TeX}{points
}
117 Thus, in order to specify, e.g., a length of
5 width points, just use
120 \section{Conversion functions
}
121 If you want to know the value of a
\PyX{} length in certain units, you
122 may use the predefined conversion functions which are given in the
124 \begin{tableii
}{l|l
}{textrm
}{function
}{result
}
125 \lineii{\texttt{tom(l)
}}{\texttt{l
} in units of m
}
126 \lineii{\texttt{tocm(l)
}}{\texttt{l
} in units of cm
}
127 \lineii{\texttt{tomm(l)
}}{\texttt{l
} in units of mm
}
128 \lineii{\texttt{toinch(l)
}}{\texttt{l
} in units of inch
}
129 \lineii{\texttt{topt(l)
}}{\texttt{l
} in units of points
}
131 If
\verb|l| is not yet a
\verb|length| instance but a number, it first
132 is interpreted as a user length in the default units.
138 %%% TeX-master: "manual.tex"
