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 \unit[1]{cm
},
\unit[50]{points
},
\unit[0.42]{inch
}. In addition,
12 lengths in
\PyX{} are composed of the five types ``true'', ``user'',
13 ``visual'', ``width'', and ``
\TeX'', e.g.,
\unit[1]{user cm
},
14 \unit[50]{true points
}, $(
0.42\
\mathrm{visual
} +
0.2\
15 \mathrm{width
})$ inch. As their names indicate, they serve different
16 purposes. True lengths are not scalable and are mainly used for return
17 values of
\PyX{} functions. The other length types can be rescaled by
18 the user and differ with respect to the type of object they are
22 \item[user length:
] used for lengths of graphical objects like
24 \item[visual length:
] used for sizes of visual elements, like arrows,
25 graph symbols, axis ticks, etc.
26 \item[width length:
] used for line widths
27 \item[\TeX{} length:
] used for all
\TeX{} and
\LaTeX{} output
30 When not specified otherwise, all types of lengths are interpreted
31 in terms of a default unit, which, by default, is
\unit[1]{cm
}.
32 You may change this default unit by using the module level function
33 \begin{funcdesc
}{set
}{uscale=None, vscale=None, wscale=None,
34 xscale=None, defaultunit=None
}
35 When
\var{uscale
},
\var{vscale
},
\var{wscale
}, or
\var{xscale
} is not
36 \keyword{None
}, the corresponding scaling factor(s) is redefined to
37 the given number. When
\var{defaultunit
} is not
\keyword{None
},
38 the default unit is set to the given value, which has to be
39 one of
\code{"cm"
},
\code{"mm"
},
\code{"inch"
}, or
\code{"pt"
}.
42 For instance, if you only want thicker lines for a publication
43 version of your figure, you can just rescale all width lengths using
47 Or suppose, you are used to specify length in imperial units. In this,
48 admittedly rather unfortunate case, just use
50 unit.set(defaultunit="inch")
52 at the beginning of your program.
54 \section{Class length
}
56 \begin{classdesc
}{length
}{f, type="u", unit=None
}
57 The constructor of the
\class{length
} class expects as its first
58 argument a number
\var{f
}, which represents the prefactor of the given length.
59 By default this length is interpreted as a user length (
\code{type="u"
}) in units
60 of the current default unit (see
\function{set()
} function of the
\module{unit
}
61 module). Optionally, a different
\var{type
} may be specified, namely
62 \code{"u"
} for user lengths,
\code{"v"
} for visual lengths,
\code{"w"
}
63 for width lengths,
\code{"x"
} for
\TeX{} length, and
\code{"t"
} for true
64 lengths. Furthermore, a different unit may be specified using the
\var{unit
}
65 argument. Allowed values are
\code{"cm"
},
\code{"mm"
},
\code{"inch"
},
69 Instances of the
\class{length
} class support addition and substraction either by another
\class{length
}
70 or by a number which is then interpeted as being a user length in
71 default units, multiplication by a number and division either by another
72 \class{length
} in which case a float is returned or by a number in which
73 case a
\class{length
} instance is returned. When two lengths are
74 compared, they are first converted to meters (using the currently set
75 scaling), and then the resulting values are compared.
77 \section{Predefined length instances
}
79 A number of
\verb|length| instances are already predefined, which
80 only differ in there values for
\verb|type| and
\verb|unit|. They are
81 summarized in the following table
85 \begin{tabular
}{lll|lll
}
86 name & type & unit & name & type & unit\\
88 \constant{m
} & user & m &
\constant{v
\_m} & visual & m\\
89 \constant{cm
} & user & cm &
\constant{v
\_cm} & visual & cm\\
90 \constant{mm
} & user & mm &
\constant{v
\_mm} & visual & mm\\
91 \constant{inch
} & user & inch &
\constant{v
\_inch} & visual & inch\\
92 \constant{pt
} & user & points &
\constant{v
\_pt} & visual & points\\
93 \constant{t
\_m} & true & m &
\constant{w
\_m} & width & m\\
94 \constant{t
\_cm} & true & cm &
\constant{w
\_cm} & width & cm\\
95 \constant{t
\_mm} & true & mm &
\constant{w
\_mm} & width & mm\\
96 \constant{t
\_inch} & true & inch &
\constant{w
\_inch} & width & inch\\
97 \constant{t
\_pt} & true & points &
\constant{w
\_pt} & width & points\\
98 \constant{u
\_m} & user & m &
\constant{x
\_m} &
\TeX & m \\
99 \constant{u
\_cm} & user & cm &
\constant{x
\_cm} &
\TeX & cm \\
100 \constant{u
\_mm} & user & mm &
\constant{x
\_mm} &
\TeX & mm \\
101 \constant{u
\_inch} & user & inch &
\constant{x
\_inch} &
\TeX & inch \\
102 \constant{u
\_pt} & user & points &
\constant{x
\_pt} &
\TeX & points\\
108 Thus, in order to specify, e.g., a length of
5 width points, just use
111 \section{Conversion functions
}
112 If you want to know the value of a
\PyX{} length in certain units, you
113 may use the predefined conversion functions which are given in the
119 \texttt{tom(l)
} &
\texttt{l
} in units of m\\
120 \texttt{tocm(l)
} &
\texttt{l
} in units of cm\\
121 \texttt{tomm(l)
} &
\texttt{l
} in units of mm\\
122 \texttt{toinch(l)
} &
\texttt{l
} in units of inch\\
123 \texttt{topt(l)
} &
\texttt{l
} in units of points\\
126 If
\verb|l| is not yet a
\verb|length| instance but a number, it first
127 is interpreted as a user length in the default units.
133 %%% TeX-master: "manual.tex"
