Related
Background
I am trying to show three variables on a single plot. I have connected the three points using lines of different colours based on some other variables. This is shown here
Problem
What I want to do is to have a different scale on the negative x-axis. This would help me in providing positive x_ticks, different axis label and also clear and uncluttered representation of the lines on left side of the image
Question
How to have a different positive x-axis starting from 0 towards negative direction?
Have xticks based on data plotted in that direction
Have a separate xlabel for this new axis
Additional information
I have checked other questions regarding inclusion of multiple axes e.g. this and this. However, these questions did not serve the purpose.
Code Used
font_size = 20
plt.rcParams.update({'font.size': font_size})
fig = plt.figure()
ax = fig.add_subplot(111)
#read my_data from file or create it
for case in my_data:
#Iterating over my_data
if condition1 == True:
local_linestyle = '-'
local_color = 'r'
local_line_alpha = 0.6
elif condition2 == 1:
local_linestyle = '-'
local_color = 'b'
local_line_alpha = 0.6
else:
local_linestyle = '--'
local_color = 'g'
local_line_alpha = 0.6
datapoint = [case[0], case[1], case[2]]
plt.plot(datapoint[0], 0, color=local_color)
plt.plot(-datapoint[2], 0, color=local_color)
plt.plot(0, datapoint[1], color=local_color)
plt.plot([datapoint[0], 0], [0, datapoint[1]], linestyle=local_linestyle, color=local_color)
plt.plot([-datapoint[2], 0], [0, datapoint[1]], linestyle=local_linestyle, color=local_color)
plt.show()
exit()
You can define a custom scale, where values below zero are scaled differently than those above zero.
import numpy as np
from matplotlib import scale as mscale
from matplotlib import transforms as mtransforms
from matplotlib.ticker import FuncFormatter
class AsymScale(mscale.ScaleBase):
name = 'asym'
def __init__(self, axis, **kwargs):
mscale.ScaleBase.__init__(self)
self.a = kwargs.get("a", 1)
def get_transform(self):
return self.AsymTrans(self.a)
def set_default_locators_and_formatters(self, axis):
# possibly, set a different locator and formatter here.
fmt = lambda x,pos: "{}".format(np.abs(x))
axis.set_major_formatter(FuncFormatter(fmt))
class AsymTrans(mtransforms.Transform):
input_dims = 1
output_dims = 1
is_separable = True
def __init__(self, a):
mtransforms.Transform.__init__(self)
self.a = a
def transform_non_affine(self, x):
return (x >= 0)*x + (x < 0)*x*self.a
def inverted(self):
return AsymScale.InvertedAsymTrans(self.a)
class InvertedAsymTrans(AsymTrans):
def transform_non_affine(self, x):
return (x >= 0)*x + (x < 0)*x/self.a
def inverted(self):
return AsymScale.AsymTrans(self.a)
Using this you would provide a scale parameter a that scales the negative part of the axes.
# Now that the Scale class has been defined, it must be registered so
# that ``matplotlib`` can find it.
mscale.register_scale(AsymScale)
import matplotlib.pyplot as plt
fig, ax = plt.subplots()
ax.plot([-2, 0, 5], [0,1,0])
ax.set_xscale("asym", a=2)
ax.annotate("negative axis", xy=(.25,0), xytext=(0,-30),
xycoords = "axes fraction", textcoords="offset points", ha="center")
ax.annotate("positive axis", xy=(.75,0), xytext=(0,-30),
xycoords = "axes fraction", textcoords="offset points", ha="center")
plt.show()
The question is not very clear about what xticks and labels are desired, so I left that out for now.
Here's how to get what you want. This solution uses two twined axes object to get different scaling to the left and right of the origin, and then hides all the evidence:
import matplotlib.pyplot as plt
import matplotlib as mpl
from numbers import Number
tickkwargs = {m+k:False for k in ('bottom','top','left','right') for m in ('','label')}
p = np.zeros((10, 3, 2))
p[:,0,0] -= np.arange(10)*.1 + .5
p[:,1,1] += np.repeat(np.arange(5), 2)*.1 + .3
p[:,2,0] += np.arange(10)*.5 + 2
fig = plt.figure(figsize=(8,6))
host = fig.add_subplot(111)
par = host.twiny()
host.set_xlim(-6, 6)
par.set_xlim(-1, 1)
for ps in p:
# mask the points with negative x values
ppos = ps[ps[:,0] >= 0].T
host.plot(*ppos)
# mask the points with positive x values
pneg = ps[ps[:,0] <= 0].T
par.plot(*pneg)
# hide all possible ticks/notation text that could be set by the second x axis
par.tick_params(axis="both", **tickkwargs)
par.xaxis.get_offset_text().set_visible(False)
# fix the x tick labels so they're all positive
host.set_xticklabels(np.abs(host.get_xticks()))
fig.show()
Output:
Here's what the set of points p I used in the code above look like when plotted normally:
fig = plt.figure(figsize=(8,6))
ax = fig.gca()
for ps in p:
ax.plot(*ps.T)
fig.show()
Output:
The method of deriving a class of mscale.ScaleBase as shown in other answers may be too complicated for your purpose.
You can pass two scale transform functions to set_xscale or set_yscale, something like the following.
def get_scale(a=1): # a is the scale of your negative axis
def forward(x):
x = (x >= 0) * x + (x < 0) * x * a
return x
def inverse(x):
x = (x >= 0) * x + (x < 0) * x / a
return x
return forward, inverse
fig, ax = plt.subplots()
forward, inverse = get_scale(a=3)
ax.set_xscale('function', functions=(forward, inverse)) # this is for setting x axis
# do plotting
More examples can be found in this doc.
Does anyone know how to implement easily colormaps to 3d bar plots in matplotlib?
Consider this example, how do I change each bar according to a colormap? For example, short bars should be mainly blue, while taller bars graduate their colors from blue towards the red...
In the physical sciences, it's common to want a so-called LEGO plot, which is I think what the original user is going for. Kevin G's answer is good and got me to the final result. Here's a more advanced histogram, for x-y scatter data, colored by height:
xAmplitudes = np.random.exponential(10,10000) #your data here
yAmplitudes = np.random.normal(50,10,10000) #your other data here - must be same array length
x = np.array(xAmplitudes) #turn x,y data into numpy arrays
y = np.array(yAmplitudes) #useful for regular matplotlib arrays
fig = plt.figure() #create a canvas, tell matplotlib it's 3d
ax = fig.add_subplot(111, projection='3d')
#make histogram stuff - set bins - I choose 20x20 because I have a lot of data
hist, xedges, yedges = np.histogram2d(x, y, bins=(20,20))
xpos, ypos = np.meshgrid(xedges[:-1]+xedges[1:], yedges[:-1]+yedges[1:])
xpos = xpos.flatten()/2.
ypos = ypos.flatten()/2.
zpos = np.zeros_like (xpos)
dx = xedges [1] - xedges [0]
dy = yedges [1] - yedges [0]
dz = hist.flatten()
cmap = cm.get_cmap('jet') # Get desired colormap - you can change this!
max_height = np.max(dz) # get range of colorbars so we can normalize
min_height = np.min(dz)
# scale each z to [0,1], and get their rgb values
rgba = [cmap((k-min_height)/max_height) for k in dz]
ax.bar3d(xpos, ypos, zpos, dx, dy, dz, color=rgba, zsort='average')
plt.title("X vs. Y Amplitudes for ____ Data")
plt.xlabel("My X data source")
plt.ylabel("My Y data source")
plt.savefig("Your_title_goes_here")
plt.show()
Note: results will vary depending on how many bins you choose and how much data you use. This code needs you to insert some data or generate a random linear array. Resulting plots are below, with two different perspectives:
So maybe not exactly what you're looking for (perhaps a good starting point for you), but using
Getting individual colors from a color map in matplotlib
can give varying solid colors for the bars:
from mpl_toolkits.mplot3d import Axes3D
import matplotlib.pyplot as plt
import matplotlib.cm as cm # import colormap stuff!
import numpy as np
fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')
x, y = np.random.rand(2, 100) * 4
hist, xedges, yedges = np.histogram2d(x, y, bins=4, range=[[0, 4], [0, 4]])
# Construct arrays for the anchor positions of the 16 bars.
# Note: np.meshgrid gives arrays in (ny, nx) so we use 'F' to flatten xpos,
# ypos in column-major order. For numpy >= 1.7, we could instead call meshgrid
# with indexing='ij'.
xpos, ypos = np.meshgrid(xedges[:-1] + 0.25, yedges[:-1] + 0.25)
xpos = xpos.flatten('F')
ypos = ypos.flatten('F')
zpos = np.zeros_like(xpos)
# Construct arrays with the dimensions for the 16 bars.
dx = 0.5 * np.ones_like(zpos)
dy = dx.copy()
dz = hist.flatten()
cmap = cm.get_cmap('jet') # Get desired colormap
max_height = np.max(dz) # get range of colorbars
min_height = np.min(dz)
# scale each z to [0,1], and get their rgb values
rgba = [cmap((k-min_height)/max_height) for k in dz]
ax.bar3d(xpos, ypos, zpos, dx, dy, dz, color=rgba, zsort='average')
plt.show()
Personally, I find that ugly as sin! But it probably won't look too bad with a sequential colormap - https://matplotlib.org/examples/color/colormaps_reference.html
I'm drawing several contour lines over a basemap projection as shown in the following figure:.
There are 3 contours that are not drawn completely (in Oregon, Washington and California) and seems like there is this line that has cut all 3 of them in the same latitude. I'm not sure how to solve this problem.
I added the number of interpolation points, didn't help. changed the ll and ur points to include more area didn't help.
The code is below (not reproducible but might help):
def visualise_bigaus(mus, sigmas, corxys , output_type='pdf', **kwargs):
lllat = 24.396308
lllon = -124.848974
urlat = 49.384358
urlon = -66.885444
fig = plt.figure(figsize=(4, 2.5))
ax = fig.add_subplot(111, axisbg='w', frame_on=False)
m = Basemap(llcrnrlat=lllat,
urcrnrlat=urlat,
llcrnrlon=lllon,
urcrnrlon=urlon,
resolution='i', projection='cyl')
m.drawmapboundary(fill_color = 'white')
#m.drawcoastlines(linewidth=0.2)
m.drawcountries(linewidth=0.2)
m.drawstates(linewidth=0.2, color='lightgray')
#m.fillcontinents(color='white', lake_color='#0000ff', zorder=2)
#m.drawrivers(color='#0000ff')
m.drawlsmask(land_color='gray',ocean_color="#b0c4de", lakes=True)
lllon, lllat = m(lllon, lllat)
urlon, urlat = m(urlon, urlat)
mlon, mlat = m(*(mus[:,1], mus[:,0]))
numcols, numrows = 1000, 1000
X = np.linspace(mlon.min(), urlon, numcols)
Y = np.linspace(lllat, urlat, numrows)
X, Y = np.meshgrid(X, Y)
m.scatter(mlon, mlat, s=0.2, c='red')
shp_info = m.readshapefile('./data/us_states_st99/st99_d00','states',drawbounds=True, zorder=0)
printed_names = []
ax = plt.gca()
ax.xaxis.set_visible(False)
ax.yaxis.set_visible(False)
for spine in ax.spines.itervalues():
spine.set_visible(False)
for k in xrange(mus.shape[0]):
#here x is longitude and y is latitude
#apply softplus to sigmas (to make them positive)
sigmax=np.log(1 + np.exp(sigmas[k][1]))
sigmay=np.log(1 + np.exp(sigmas[k][0]))
mux=mlon[k]
muy=mlat[k]
corxy = corxys[k]
#apply the soft sign
corxy = corxy / (1 + np.abs(corxy))
#now given corxy find sigmaxy
sigmaxy = corxy * sigmax * sigmay
#corxy = 1.0 / (1 + np.abs(sigmaxy))
Z = mlab.bivariate_normal(X, Y, sigmax=sigmax, sigmay=sigmay, mux=mux, muy=muy, sigmaxy=sigmaxy)
#Z = maskoceans(X, Y, Z)
con = m.contour(X, Y, Z, levels=[0.02], linewidths=0.5, colors='darkorange', antialiased=True)
'''
num_levels = len(con.collections)
if num_levels > 1:
for i in range(0, num_levels):
if i != (num_levels-1):
con.collections[i].set_visible(False)
'''
contour_labels = False
if contour_labels:
plt.clabel(con, [con.levels[-1]], inline=True, fontsize=10)
'''
world_shp_info = m.readshapefile('./data/CNTR_2014_10M_SH/Data/CNTR_RG_10M_2014','world',drawbounds=False, zorder=100)
for shapedict,state in zip(m.world_info, m.world):
if shapedict['CNTR_ID'] not in ['CA', 'MX']: continue
poly = MplPolygon(state,facecolor='gray',edgecolor='gray')
ax.add_patch(poly)
'''
if iter:
iter = str(iter).zfill(3)
else:
iter = ''
plt.tight_layout()
plt.savefig('./maps/video/gaus_' + iter + '.' + output_type, frameon=False, dpi=200)
The problem is the meshgrid not covering the complete map. The meshgrid simply doesn't have any points at the positions where you want to draw the gaussian contour line.
An example to reproduce this behaviour is the following, where the meshgrid in x directio starts at -1, such that points lower than that are not drawn.
import matplotlib.pyplot as plt
import matplotlib.mlab as mlab
import numpy as np
fig, ax=plt.subplots()
ax.plot([-2,2],[-2,-2], alpha=0)
X,Y = np.meshgrid(np.linspace(-1,2),np.linspace(-2,2))
Z = mlab.bivariate_normal(X, Y, sigmax=1., sigmay=1., mux=0.1, muy=0.1, sigmaxy=0)
con = ax.contour(X, Y, Z, levels=[Z.max()/3, Z.max()/2., Z.max()*0.8],colors='darkorange')
plt.show()
A similar problem occurs in the code from the question.
While in Y direction, you use the complete map, Y = np.linspace(lllat, urlat, numrows), in X direction you restrict the mesh to start at mlon.min(),
X = np.linspace(mlon.min(), urlon, numcols)
The solution would of course be not to start the mesh in Portland, but somewhere in the ocean, i.e. at the edge of the shown map.
Right now there're some statistics plotted in 3d bar over (x, y). each bar height represents the density of the points in side the square grid of (x,y) plane. Right now, i can put different color on each bar. However, I want to put progressive color on the 3d bar, similar as the cmap, so the bar will be gradient filled depending on the density.
from mpl_toolkits.mplot3d import Axes3D
import matplotlib.pyplot as plt
import numpy as np
fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')
# height of the bars
z = np.ones((4, 4)) * np.arange(4)
# position of the bars
xpos, ypos = np.meshgrid(np.arange(4), np.arange(4))
xpos = xpos.flatten('F')
ypos = ypos.flatten('F')
zpos = np.zeros_like(xpos)
dx = 0.5 * np.ones_like(zpos)
dy = dx.copy()
dz = z.flatten()
ax.bar3d(xpos, ypos, zpos, dx, dy, dz, color='b', zsort='average')
plt.show()
Output the above code:
Let me first say that matplotlib may not be the tool of choice when it comes to sophisticated 3D plots.
That said, there is no built-in method to produce bar plots with differing colors over the extend of the bar.
We therefore need to mimic the bar somehow. A possible solution can be found below. Here, we use a plot_surface plot to create a bar that contains a gradient.
from mpl_toolkits.mplot3d import Axes3D
import matplotlib.pyplot as plt
import matplotlib.colors
import numpy as np
fig = plt.figure()
ax = fig.add_subplot(111, projection= Axes3D.name)
def make_bar(ax, x0=0, y0=0, width = 0.5, height=1 , cmap="viridis",
norm=matplotlib.colors.Normalize(vmin=0, vmax=1), **kwargs ):
# Make data
u = np.linspace(0, 2*np.pi, 4+1)+np.pi/4.
v_ = np.linspace(np.pi/4., 3./4*np.pi, 100)
v = np.linspace(0, np.pi, len(v_)+2 )
v[0] = 0 ; v[-1] = np.pi; v[1:-1] = v_
x = np.outer(np.cos(u), np.sin(v))
y = np.outer(np.sin(u), np.sin(v))
z = np.outer(np.ones(np.size(u)), np.cos(v))
xthr = np.sin(np.pi/4.)**2 ; zthr = np.sin(np.pi/4.)
x[x > xthr] = xthr; x[x < -xthr] = -xthr
y[y > xthr] = xthr; y[y < -xthr] = -xthr
z[z > zthr] = zthr ; z[z < -zthr] = -zthr
x *= 1./xthr*width; y *= 1./xthr*width
z += zthr
z *= height/(2.*zthr)
#translate
x += x0; y += y0
#plot
ax.plot_surface(x, y, z, cmap=cmap, norm=norm, **kwargs)
def make_bars(ax, x, y, height, width=1):
widths = np.array(width)*np.ones_like(x)
x = np.array(x).flatten()
y = np.array(y).flatten()
h = np.array(height).flatten()
w = np.array(widths).flatten()
norm = matplotlib.colors.Normalize(vmin=0, vmax=h.max())
for i in range(len(x.flatten())):
make_bar(ax, x0=x[i], y0=y[i], width = w[i] , height=h[i], norm=norm)
X, Y = np.meshgrid([1,2,3], [2,3,4])
Z = np.sin(X*Y)+1.5
make_bars(ax, X,Y,Z, width=0.2, )
plt.show()
How can I annotate a range of my data? E.g., say the data from x = 5 to x = 10 is larger than some cut-off, how could I indicate that on the graph. If I was annotating by hand, I would just draw a large bracket above the range and write my annotation above the bracket.
The closest I've seen is using arrowstyle='<->' and connectionstyle='bar', to make two arrows pointing to the edges of your data with a line connecting their tails. But that doesn't quite do the right thing; the text that you enter for the annotation will end up under one of the arrows, rather than above the bar.
Here is my attempt, along with it's results:
annotate(' ', xy=(1,.5), xycoords='data',
xytext=(190, .5), textcoords='data',
arrowprops=dict(arrowstyle="<->",
connectionstyle="bar",
ec="k",
shrinkA=5, shrinkB=5,
)
)
Another problem with my attempted solution is that the squared shape of the annotating bracket does not really make it clear that I am highlighting a range (unlike, e.g., a curly brace). But I suppose that's just being nitpicky at this point.
As mentioned in this answer, you can construct curly brackets with sigmoidal functions. Below is a function that adds curly brackets just above the x-axis. The curly brackets it produces should look the same regardless of the axes limits, as long as the figure width and height don't vary.
import numpy as np
import matplotlib.pyplot as plt
def draw_brace(ax, xspan, text):
"""Draws an annotated brace on the axes."""
xmin, xmax = xspan
xspan = xmax - xmin
ax_xmin, ax_xmax = ax.get_xlim()
xax_span = ax_xmax - ax_xmin
ymin, ymax = ax.get_ylim()
yspan = ymax - ymin
resolution = int(xspan/xax_span*100)*2+1 # guaranteed uneven
beta = 300./xax_span # the higher this is, the smaller the radius
x = np.linspace(xmin, xmax, resolution)
x_half = x[:resolution//2+1]
y_half_brace = (1/(1.+np.exp(-beta*(x_half-x_half[0])))
+ 1/(1.+np.exp(-beta*(x_half-x_half[-1]))))
y = np.concatenate((y_half_brace, y_half_brace[-2::-1]))
y = ymin + (.05*y - .01)*yspan # adjust vertical position
ax.autoscale(False)
ax.plot(x, y, color='black', lw=1)
ax.text((xmax+xmin)/2., ymin+.07*yspan, text, ha='center', va='bottom')
ax = plt.gca()
ax.plot(range(10))
draw_brace(ax, (0, 8), 'large brace')
draw_brace(ax, (8, 9), 'small brace')
Output:
I modified Joooeey's answer to allow to change the vertical position of braces:
def draw_brace(ax, xspan, yy, text):
"""Draws an annotated brace on the axes."""
xmin, xmax = xspan
xspan = xmax - xmin
ax_xmin, ax_xmax = ax.get_xlim()
xax_span = ax_xmax - ax_xmin
ymin, ymax = ax.get_ylim()
yspan = ymax - ymin
resolution = int(xspan/xax_span*100)*2+1 # guaranteed uneven
beta = 300./xax_span # the higher this is, the smaller the radius
x = np.linspace(xmin, xmax, resolution)
x_half = x[:int(resolution/2)+1]
y_half_brace = (1/(1.+np.exp(-beta*(x_half-x_half[0])))
+ 1/(1.+np.exp(-beta*(x_half-x_half[-1]))))
y = np.concatenate((y_half_brace, y_half_brace[-2::-1]))
y = yy + (.05*y - .01)*yspan # adjust vertical position
ax.autoscale(False)
ax.plot(x, y, color='black', lw=1)
ax.text((xmax+xmin)/2., yy+.07*yspan, text, ha='center', va='bottom')
ax = plt.gca()
ax.plot(range(10))
draw_brace(ax, (0, 8), -0.5, 'large brace')
draw_brace(ax, (8, 9), 3, 'small brace')
Output:
Also note that in Joooeey's answer, line
x_half = x[:resolution/2+1]
should be
x_half = x[:int(resolution/2)+1]
Otherwise, the number that the script tries to use as index here is a float.
Finally, note that right now the brace will not show up if you move it out of bounds. You need to add parameter clip_on=False, like this:
ax.plot(x, y, color='black', lw=1, clip_on=False)
You can just wrap it all up in a function:
def add_range_annotation(ax, start, end, txt_str, y_height=.5, txt_kwargs=None, arrow_kwargs=None):
"""
Adds horizontal arrow annotation with text in the middle
Parameters
----------
ax : matplotlib.Axes
The axes to draw to
start : float
start of line
end : float
end of line
txt_str : string
The text to add
y_height : float
The height of the line
txt_kwargs : dict or None
Extra kwargs to pass to the text
arrow_kwargs : dict or None
Extra kwargs to pass to the annotate
Returns
-------
tuple
(annotation, text)
"""
if txt_kwargs is None:
txt_kwargs = {}
if arrow_kwargs is None:
# default to your arrowprops
arrow_kwargs = {'arrowprops':dict(arrowstyle="<->",
connectionstyle="bar",
ec="k",
shrinkA=5, shrinkB=5,
)}
trans = ax.get_xaxis_transform()
ann = ax.annotate('', xy=(start, y_height),
xytext=(end, y_height),
transform=trans,
**arrow_kwargs)
txt = ax.text((start + end) / 2,
y_height + .05,
txt_str,
**txt_kwargs)
if plt.isinteractive():
plt.draw()
return ann, txt
Alternately,
start, end = .6, .8
ax.axvspan(start, end, alpha=.2, color='r')
trans = ax.get_xaxis_transform()
ax.text((start + end) / 2, .5, 'test', transform=trans)
Here is a minor modification to guzey and jooeey's answer to plot the flower braces outside the axes.
def draw_brace(ax, xspan, yy, text):
"""Draws an annotated brace outside the axes."""
xmin, xmax = xspan
xspan = xmax - xmin
ax_xmin, ax_xmax = ax.get_xlim()
xax_span = ax_xmax - ax_xmin
ymin, ymax = ax.get_ylim()
yspan = ymax - ymin
resolution = int(xspan/xax_span*100)*2+1 # guaranteed uneven
beta = 300./xax_span # the higher this is, the smaller the radius
x = np.linspace(xmin, xmax, resolution)
x_half = x[:int(resolution/2)+1]
y_half_brace = (1/(1.+np.exp(-beta*(x_half-x_half[0])))
+ 1/(1.+np.exp(-beta*(x_half-x_half[-1]))))
y = np.concatenate((y_half_brace, y_half_brace[-2::-1]))
y = yy + (.05*y - .01)*yspan # adjust vertical position
ax.autoscale(False)
ax.plot(x, -y, color='black', lw=1, clip_on=False)
ax.text((xmax+xmin)/2., -yy-.17*yspan, text, ha='center', va='bottom')
# Sample code
fmax = 1
fstart = -100
fend = 0
frise = 50
ffall = 20
def S(x):
if x<=0:
return 0
elif x>=1:
return 1
else:
return 1/(1+np.exp((1/(x-1))+(1/x)))
x = np.linspace(700,1000,500)
lam = [fmax*(S((i-880)/60)-S(((i-1000)/25)+1)) for i in x]
fig = plt.figure(1)
ax = fig.add_subplot(111)
plt.plot(x,lam)
plt.xlim([850,1000])
ax.set_aspect(50,adjustable='box')
plt.ylabel('$\lambda$')
plt.xlabel('$x$')
ax.xaxis.set_label_coords(0.5, -0.35)
draw_brace(ax, (900,950),0.2, 'rise')
draw_brace(ax, (980,1000),0.2, 'fall')
plt.text(822,0.95,'$(\lambda_{\mathrm{max}})$')
Sample output
a minor modification of the draw_brace of #Joooeey and #guezy to have also the brace upside down
+argument upsidedown
def draw_brace(ax, xspan, yy, text, upsidedown=False):
"""Draws an annotated brace on the axes."""
# shamelessly copied from https://stackoverflow.com/questions/18386210/annotating-ranges-of-data-in-matplotlib
xmin, xmax = xspan
xspan = xmax - xmin
ax_xmin, ax_xmax = ax.get_xlim()
xax_span = ax_xmax - ax_xmin
ymin, ymax = ax.get_ylim()
yspan = ymax - ymin
resolution = int(xspan/xax_span*100)*2+1 # guaranteed uneven
beta = 300./xax_span # the higher this is, the smaller the radius
x = np.linspace(xmin, xmax, resolution)
x_half = x[:int(resolution/2)+1]
y_half_brace = (1/(1.+np.exp(-beta*(x_half-x_half[0])))
+ 1/(1.+np.exp(-beta*(x_half-x_half[-1]))))
if upsidedown:
y = np.concatenate((y_half_brace[-2::-1], y_half_brace))
else:
y = np.concatenate((y_half_brace, y_half_brace[-2::-1]))
y = yy + (.05*y - .01)*yspan # adjust vertical position
ax.autoscale(False)
line = ax.plot(x, y, color='black', lw=1)
if upsidedown:
text = ax.text((xmax+xmin)/2., yy+-.07*yspan, text, ha='center', va='bottom',fontsize=7)
else:
text = ax.text((xmax+xmin)/2., yy+.07*yspan, text, ha='center', va='bottom',fontsize=7)
return line, text
I updated the previous answers to have some of the features I wanted, like an option for a vertical brace, that I wanted to place in multi-plot figures. One still has to futz with the beta_scale parameter sometimes depending on the scale of the data that one is applying this to.
def rotate_point(x, y, angle_rad):
cos,sin = np.cos(angle_rad),np.sin(angle_rad)
return cos*x-sin*y,sin*x+cos*y
def draw_brace(ax, span, position, text, text_pos, brace_scale=1.0, beta_scale=300., rotate=False, rotate_text=False):
'''
all positions and sizes are in axes units
span: size of the curl
position: placement of the tip of the curl
text: label to place somewhere
text_pos: position for the label
beta_scale: scaling for the curl, higher makes a smaller radius
rotate: true rotates to place the curl vertically
rotate_text: true rotates the text vertically
'''
# get the total width to help scale the figure
ax_xmin, ax_xmax = ax.get_xlim()
xax_span = ax_xmax - ax_xmin
resolution = int(span/xax_span*100)*2+1 # guaranteed uneven
beta = beta_scale/xax_span # the higher this is, the smaller the radius
# center the shape at (0, 0)
x = np.linspace(-span/2., span/2., resolution)
# calculate the shape
x_half = x[:int(resolution/2)+1]
y_half_brace = (1/(1.+np.exp(-beta*(x_half-x_half[0])))
+ 1/(1.+np.exp(-beta*(x_half-x_half[-1]))))
y = np.concatenate((y_half_brace, y_half_brace[-2::-1]))
# put the tip of the curl at (0, 0)
max_y = np.max(y)
min_y = np.min(y)
y /= (max_y-min_y)
y *= brace_scale
y -= max_y
# rotate the trace before shifting
if rotate:
x,y = rotate_point(x, y, np.pi/2)
# shift to the user's spot
x += position[0]
y += position[1]
ax.autoscale(False)
ax.plot(x, y, color='black', lw=1, clip_on=False)
# put the text
ax.text(text_pos[0], text_pos[1], text, ha='center', va='bottom', rotation=90 if rotate_text else 0)