This module contains classes to support completely configurable tick locating and formatting. Although the locators know nothing about major or minor ticks, they are used by the Axis class to support major and minor tick locating and formatting. Generic tick locators and formatters are provided, as well as domain specific custom ones..
The default formatter identifies when the x-data being plotted is a small range on top of a large off set. To reduce the chances that the ticklabels overlap the ticks are labeled as deltas from a fixed offset. For example:
ax.plot(np.arange(2000, 2010), range(10))
will have tick of 0-9 with an offset of +2e3. If this is not desired turn off the use of the offset on the default formatter:
ax.get_xaxis().get_major_formatter().set_useOffset(False)
set the rcParam axes.formatter.useoffset=False
to turn it off globally, or set a different formatter.
The Locator class is the base class for all tick locators. The locators handle autoscaling of the view limits based on the data limits, and the choosing of tick locations. A useful semi-automatic tick locator is MultipleLocator. You initialize this with a base, e.g., 10, and it picks axis limits and ticks that are multiples of your base.
The Locator subclasses defined here are
NullLocator
FixedLocator
IndexLocator
LinearLocator
LogLocator
SymmetricalLogLocator
LogLocator
for the part outside of the threshold and add 0 if inside the limitsMultipleLocator
OldAutoLocator
MaxNLocator
AutoLocator
MaxNLocator
with simple defaults. This is the default tick locator for most plotting.AutoMinorLocator
There are a number of locators specialized for date locations - see the dates module
You can define your own locator by deriving from Locator. You must override the __call__ method, which returns a sequence of locations, and you will probably want to override the autoscale method to set the view limits from the data limits.
If you want to override the default locator, use one of the above or a custom locator and pass it to the x or y axis instance. The relevant methods are:
ax.xaxis.set_major_locator( xmajorLocator ) ax.xaxis.set_minor_locator( xminorLocator ) ax.yaxis.set_major_locator( ymajorLocator ) ax.yaxis.set_minor_locator( yminorLocator )
The default minor locator is the NullLocator, e.g., no minor ticks on by default.
Tick formatting is controlled by classes derived from Formatter. The formatter operates on a single tick value and returns a string to the axis.
NullFormatter
IndexFormatter
FixedFormatter
FuncFormatter
StrMethodFormatter
format
methodFormatStrFormatter
ScalarFormatter
LogFormatter
You can derive your own formatter from the Formatter base class by simply overriding the __call__
method. The formatter class has access to the axis view and data limits.
To control the major and minor tick label formats, use one of the following methods:
ax.xaxis.set_major_formatter( xmajorFormatter ) ax.xaxis.set_minor_formatter( xminorFormatter ) ax.yaxis.set_major_formatter( ymajorFormatter ) ax.yaxis.set_minor_formatter( yminorFormatter )
See pylab_examples example code: major_minor_demo1.py for an example of setting major and minor ticks. See the matplotlib.dates
module for more information and examples of using date locators and formatters.
class matplotlib.ticker.TickHelper
Bases: object
axis = None
create_dummy_axis(**kwargs)
set_axis(axis)
set_bounds(vmin, vmax)
set_data_interval(vmin, vmax)
set_view_interval(vmin, vmax)
class matplotlib.ticker.Formatter
Bases: matplotlib.ticker.TickHelper
Convert the tick location to a string
fix_minus(s)
Some classes may want to replace a hyphen for minus with the proper unicode symbol (U+2212) for typographical correctness. The default is to not replace it.
Note, if you use this method, e.g., in format_data()
or call, you probably don’t want to use it for format_data_short()
since the toolbar uses this for interactive coord reporting and I doubt we can expect GUIs across platforms will handle the unicode correctly. So for now the classes that override fix_minus()
should have an explicit format_data_short()
method
format_data(value)
format_data_short(value)
return a short string version
get_offset()
locs = []
set_locs(locs)
class matplotlib.ticker.FixedFormatter(seq)
Bases: matplotlib.ticker.Formatter
Return fixed strings for tick labels
seq is a sequence of strings. For positions i < len(seq)
return seq[i] regardless of x. Otherwise return ‘’
get_offset()
set_offset_string(ofs)
class matplotlib.ticker.NullFormatter
Bases: matplotlib.ticker.Formatter
Always return the empty string
class matplotlib.ticker.FuncFormatter(func)
Bases: matplotlib.ticker.Formatter
User defined function for formatting
The function should take in two inputs (tick value x and position pos) and return a string
class matplotlib.ticker.FormatStrFormatter(fmt)
Bases: matplotlib.ticker.Formatter
Use an old-style (‘%’ operator) format string to format the tick
class matplotlib.ticker.StrMethodFormatter(fmt)
Bases: matplotlib.ticker.Formatter
Use a new-style format string (as used by str.format()
) to format the tick. The field formatting must be labeled x
.
class matplotlib.ticker.ScalarFormatter(useOffset=None, useMathText=None, useLocale=None)
Bases: matplotlib.ticker.Formatter
Tick location is a plain old number. If useOffset==True and the data range is much smaller than the data average, then an offset will be determined such that the tick labels are meaningful. Scientific notation is used for data < 10^-n or data >= 10^m, where n and m are the power limits set using set_powerlimits((n,m)). The defaults for these are controlled by the axes.formatter.limits rc parameter.
fix_minus(s)
use a unicode minus rather than hyphen
format_data(value)
return a formatted string representation of a number
format_data_short(value)
return a short formatted string representation of a number
get_offset()
Return scientific notation, plus offset
get_useLocale()
get_useOffset()
pprint_val(x)
set_locs(locs)
set the locations of the ticks
set_powerlimits(lims)
Sets size thresholds for scientific notation.
e.g., formatter.set_powerlimits((-3, 4))
sets the pre-2007 default in which scientific notation is used for numbers less than 1e-3 or greater than 1e4. See also set_scientific()
.
set_scientific(b)
True or False to turn scientific notation on or off see also set_powerlimits()
set_useLocale(val)
set_useOffset(val)
useLocale
useOffset
class matplotlib.ticker.LogFormatter(base=10.0, labelOnlyBase=True)
Bases: matplotlib.ticker.Formatter
Format values for log axis;
base is used to locate the decade tick, which will be the only one to be labeled if labelOnlyBase is False
base(base)
change the base for labeling - warning: should always match the base used for LogLocator
format_data(value)
format_data_short(value)
return a short formatted string representation of a number
label_minor(labelOnlyBase)
switch on/off minor ticks labeling
pprint_val(x, d)
class matplotlib.ticker.LogFormatterExponent(base=10.0, labelOnlyBase=True)
Bases: matplotlib.ticker.LogFormatter
Format values for log axis; using exponent = log_base(value)
base is used to locate the decade tick, which will be the only one to be labeled if labelOnlyBase is False
class matplotlib.ticker.LogFormatterMathtext(base=10.0, labelOnlyBase=True)
Bases: matplotlib.ticker.LogFormatter
Format values for log axis; using exponent = log_base(value)
base is used to locate the decade tick, which will be the only one to be labeled if labelOnlyBase is False
class matplotlib.ticker.Locator
Bases: matplotlib.ticker.TickHelper
Determine the tick locations;
Note, you should not use the same locator between different Axis
because the locator stores references to the Axis data and view limits
MAXTICKS = 1000
autoscale()
autoscale the view limits
pan(numsteps)
Pan numticks (can be positive or negative)
raise_if_exceeds(locs)
raise a RuntimeError if Locator attempts to create more than MAXTICKS locs
refresh()
refresh internal information based on current lim
set_params(**kwargs)
Do nothing, and rase a warning. Any locator class not supporting the set_params() function will call this.
tick_values(vmin, vmax)
Return the values of the located ticks given vmin and vmax.
Note
To get tick locations with the vmin and vmax values defined automatically for the associated axis
simply call the Locator instance:
>>> print((type(loc))) <type 'Locator'> >>> print((loc())) [1, 2, 3, 4]
view_limits(vmin, vmax)
select a scale for the range from vmin to vmax
Normally this method is overridden by subclasses to change locator behaviour.
zoom(direction)
Zoom in/out on axis; if direction is >0 zoom in, else zoom out
class matplotlib.ticker.IndexLocator(base, offset)
Bases: matplotlib.ticker.Locator
Place a tick on every multiple of some base number of points plotted, e.g., on every 5th point. It is assumed that you are doing index plotting; i.e., the axis is 0, len(data). This is mainly useful for x ticks.
place ticks on the i-th data points where (i-offset)%base==0
set_params(base=None, offset=None)
Set parameters within this locator
tick_values(vmin, vmax)
class matplotlib.ticker.FixedLocator(locs, nbins=None)
Bases: matplotlib.ticker.Locator
Tick locations are fixed. If nbins is not None, the array of possible positions will be subsampled to keep the number of ticks <= nbins +1. The subsampling will be done so as to include the smallest absolute value; for example, if zero is included in the array of possibilities, then it is guaranteed to be one of the chosen ticks.
set_params(nbins=None)
Set parameters within this locator.
tick_values(vmin, vmax)
” Return the locations of the ticks.
Note
Because the values are fixed, vmin and vmax are not used in this method.
class matplotlib.ticker.NullLocator
Bases: matplotlib.ticker.Locator
No ticks
tick_values(vmin, vmax)
” Return the locations of the ticks.
Note
Because the values are Null, vmin and vmax are not used in this method.
class matplotlib.ticker.LinearLocator(numticks=None, presets=None)
Bases: matplotlib.ticker.Locator
Determine the tick locations
The first time this function is called it will try to set the number of ticks to make a nice tick partitioning. Thereafter the number of ticks will be fixed so that interactive navigation will be nice
Use presets to set locs based on lom. A dict mapping vmin, vmax->locs
set_params(numticks=None, presets=None)
Set parameters within this locator.
tick_values(vmin, vmax)
view_limits(vmin, vmax)
Try to choose the view limits intelligently
class matplotlib.ticker.LogLocator(base=10.0, subs=[1.0], numdecs=4, numticks=15)
Bases: matplotlib.ticker.Locator
Determine the tick locations for log axes
place ticks on the location= base**i*subs[j]
base(base)
set the base of the log scaling (major tick every base**i, i integer)
set_params(base=None, subs=None, numdecs=None, numticks=None)
Set parameters within this locator.
subs(subs)
set the minor ticks the log scaling every base**i*subs[j]
tick_values(vmin, vmax)
view_limits(vmin, vmax)
Try to choose the view limits intelligently
class matplotlib.ticker.AutoLocator
class matplotlib.ticker.MultipleLocator(base=1.0)
Bases: matplotlib.ticker.Locator
Set a tick on every integer that is multiple of base in the view interval
set_params(base)
Set parameters within this locator.
tick_values(vmin, vmax)
view_limits(dmin, dmax)
Set the view limits to the nearest multiples of base that contain the data
class matplotlib.ticker.MaxNLocator(*args, **kwargs)
Bases: matplotlib.ticker.Locator
Select no more than N intervals at nice locations.
Keyword args:
bin_boundaries(vmin, vmax)
default_params = {'nbins': 10, 'prune': None, 'symmetric': False, 'steps': None, 'integer': False, 'trim': True}
set_params(**kwargs)
Set parameters within this locator.
tick_values(vmin, vmax)
view_limits(dmin, dmax)
class matplotlib.ticker.AutoMinorLocator(n=None)
Bases: matplotlib.ticker.Locator
Dynamically find minor tick positions based on the positions of major ticks. Assumes the scale is linear and major ticks are evenly spaced.
n is the number of subdivisions of the interval between major ticks; e.g., n=2 will place a single minor tick midway between major ticks.
If n is omitted or None, it will be set to 5 or 4.
tick_values(vmin, vmax)
class matplotlib.ticker.SymmetricalLogLocator(transform, subs=None)
Bases: matplotlib.ticker.Locator
Determine the tick locations for log axes
place ticks on the location= base**i*subs[j]
set_params(subs=None, numticks=None)
Set parameters within this locator.
tick_values(vmin, vmax)
view_limits(vmin, vmax)
Try to choose the view limits intelligently
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