minilineplot 0.0.6

A single Python module, with no dependencies, producing an SVG image of a chart with one or more plotted lines

minilineplot

minilineplot.py is a single Python module, with no dependencies, producing an SVG image of a chart with one or more plotted lines.

The chart has a left vertical axis and a bottom horizontal axis, grid lines are possible,

Two classes are defined.

Line, containing x,y points which creates a line to be plotted

Axis which creates the axis, and to which Line objects can be added.

The Axis class has methods to create an svg string suitable for embedding in an html document it can also create an svg image, either as a bytes object, or saved to a file.

Line

Arguments

values a list of x,y tuples, x and y being integers or floats.

color an SVG color of the line, such as 'blue'.

stroke line width, 1 for a thin line, default is 3.

label A label string for a key, if not given, the key will not be drawn

x,y values should be values between the min and max Axis attributes

color is an SVG color, using standard strings such as

Color Names: "red", "blue" etc.

Hex Codes: "#FF0000" for red.

RGB/RGBA: "rgb(255,0,0)" or "rgba(255,0,0,0.5)" (with opacity).

HSL/HSLA: "hsl(0,100%,50%)" or "hsla(0,100%,50%,0.5)" (hue, saturation, lightness, alpha)

Axis

Arguments

lines list of Line objects

fontsize default 24

imagewidth default 800

imageheight default 600

xstrings an optional list of strings used as the x axis values, use for text values such as months, etc.,

If xstrings is left empty, the following two arguments will define the x axis text

xformat default string ".1f" Sets how the x axis numbers are formatted.

xintervals default 5, the interval spacing of values along the x axis, 5 would be five intervals and six values.

The above values are ignored if xstrings is populated.

xmin default 0, the minimum x value

xmax default 100, the maximum x value

ystrings an optional list of strings used as the y axis values.

If ystrings is left empty, the following two arguments will define the y axis text

yformat default string ".1f" Sets how the y axis numbers are formatted.

yintervals default 5, the interval spacing of values along the y axis, 5 would be five intervals and six values.

The above values are ignored if ystrings is populated.

ymin default 0, the minimum y value

ymax default 100, the maximum y value

title default "", A string printed at the top of the chart

description default "", A string printed at the bottom of the chart

verticalgrid default 1

0 is no vertical grid lines, 1 is a line for every x axis interval, 2 is a line for every second interval etc.,

horizontalgrid default 1

0 is no horizontal grid lines, 1 is a line for every y axis interval, 2 is a line for every second interval etc.,

The following colors are SVG colors, using standard strings

gridcol default "grey" Color of the chart grid

axiscol default "black" Color of axis, title and description

chartbackcol default "white" the background colour of the chart

backcol default "white" The background colour of the whole image

xformat and yformat are strings describing how numbers are printed, for example the string ".2f" gives a number to two decimal places.

If chart text starts overlapping, either decrease font size, or increase the image size while keeping fontsize the same.

All arguments are also object attributes, and can be changed as required.

Methods

auto_x()

If xstrings has a value this does nothing, just returns. Otherwise it inspects the lines and auto chooses x axis values which it sets into self.xmax, self.xmin, self.xformat and self.xintervals.

This could be usefull for generated line data, or for initiall viewing after which better values could be chosen.

auto_y()

If ystrings has a value this does nothing, just returns. Otherwise it inspects the lines and auto picks y axis values which it sets into self.ymax, self.ymin, self.yformat and self.yintervals.

to_string(xml_declaration = False)

Return a string SVG object. If xml_declaration is True, an xml tag will be included in the returned string which is usually required when creating an svg image file but not required if embedding the code directly into an html document,

to_bytes(xml_declaration = True)

Return a bytes SVG object.

to_file(filepath)

Save the plot to an svg image file

To install, either use Pypi, or simply copy minilineplot.py to your own project files, or just cut and paste the contents. The code is public domain.

Note, to keep things simple there is very little data validation, rubbish in = rubbish out.

A typical example might be:

line1 = Line(values = [(0,15), (2,20), (4, 50), (6, 75), (10, 60)],
             color = "green",
             label = "green line")
example = Axis( [line1],
                title = "Example Chart",
                description = "Fig 1 : Example chart")
example.auto_x()
example.auto_y()
example.to_file("test.svg")