How to set all the four axes with matplotlib - python

I want to draw a picture like this one, the top and right axes have different labels and ticks, anyone can help me?

To double both axes you have to use ax1.twinx().twiny().
Here an example:
# Create some mock data
x1 = np.arange(0, 10, 1)
y1 = [random.randint(1,5) for n in x1]
#print(x1,y1)
x2 = np.arange(0, 100, 10)
y2 = [random.randint(10,50) for n in x2]
#print(x2,y2)
fig, ax1 = plt.subplots()
ax1.set_xlabel('x1', color='red')
ax1.set_ylabel('y1', color='red')
ax1.plot(x1, y1, color='red')
ax1.tick_params(axis='both', labelcolor='red')
ax2 = ax1.twinx().twiny() #here is the trick!
ax2.set_xlabel('x2', color='blue')
ax2.set_ylabel('y2', color='blue')
ax2.plot(x2, y2, color='blue')
ax2.tick_params(axis='both', labelcolor='blue') #y2 does not get blue... can't yet figure out why
plt.show()
Here the result:

Since both datasets are completely independent, one would probably not use twin axes here. Instead, just use two different axes.
import numpy as np
import matplotlib.pyplot as plt
# Create some mock data
x1 = np.linspace(0,1,11)
y1 = np.random.rand(11)
x2 = np.linspace(1,0,101)
y2 = np.random.rand(101)*20+20
fig, ax1 = plt.subplots()
ax2 = fig.add_subplot(111, label="second axes")
ax2.set_facecolor("none")
ax1.set_xlabel('x1', color='red')
ax1.set_ylabel('y1', color='red')
ax1.plot(x1, y1, color='red')
ax1.tick_params(colors='red')
ax2.set_xlabel('x2', color='blue')
ax2.set_ylabel('y2', color='blue')
ax2.plot(x2, y2, color='blue')
ax2.xaxis.tick_top()
ax2.xaxis.set_label_position('top')
ax2.yaxis.tick_right()
ax2.yaxis.set_label_position('right')
ax2.tick_params(colors='blue')
for which in ["top", "right"]:
ax2.spines[which].set_color("blue")
ax1.spines[which].set_visible(False)
for which in ["bottom", "left"]:
ax1.spines[which].set_color("red")
ax2.spines[which].set_visible(False)
plt.show()

You should use twinx and twiny functions, take a look at this link

Related

matplotlib hist2d: how to show counts on colorbar

I want to plot two heatmaps side by side, using figures and axes, but I can't seem to get the colorbar to show the counts for each color.
It works when I use the procedural style like this:
x1 = np.random.normal(size=1000)
y1 = np.random.normal(size=1000)
cmap = mpl.cm.plasma
plt.hist2d(x1, y1, cmap=cmap, bins=30)
plt.colorbar()
plt.show()
but not when I uses the OOP style:
x1 = np.random.normal(size=1000)
y1 = np.random.normal(size=1000)
fig, ax1 = plt.subplots(1, 1)
cmap = mpl.cm.plasma
ax1.hist2d(x1, y1, cmap=cmap, bins=30)
fig.colorbar(mpl.cm.ScalarMappable(cmap=cmap), ax=ax1)
plt.show()
The problem has to do with normalization of data for 2d histograms. The solution is here.
Thank you #JustLearning
I used numpy's histogram2d to get the values and then normalized it as follows:
h, xe, ye = np.histogram2d(x1, y1)
vmin = np.min(h)
vmax = np.max(h)
cmap = mpl.cm.plasma
norm = mpl.colors.Normalize(vmin=vmin, vmax=vmax)
sm = mpl.cm.ScalarMappable(norm=norm, cmap=cmap)
fig, ax1 = plt.subplots(1, 1)
ax1.hist2d(x1, y1, cmap=cmap, bins=30)
fig.colorbar(mappable=sm, ax=ax1)
plt.show()

Making the lines of the scatter plot smooth in MatPlotlib

I want to make the lines of the following graph smooth. I tried to search and it seems that we have to represent the x-axis in terms of a float or some type such as date time. Here since the x-axis are just labels, I could not figure out how I should change my code. Any help is appreciated.
import matplotlib.pyplot as plt
x1 = [">1", ">10",">20"]
y1 = [18,8,3]
y2 = [22,15,10]
y3=[32,17,11]
fig = plt.figure()
ax1 = fig.add_subplot(111)
ax1.scatter(x1, y1, color='blue', label='Heuristic')
ax1.scatter(x1, y2, color='green', label='SAFE')
ax1.scatter(x1, y3, color='red', label='discovRE')
plt.plot(x1, y2, '.g:')
plt.plot(x1, y1, '.b:')
plt.plot(x1, y3, '.r:')
plt.ylabel('False Positives',fontsize=8)
plt.xlabel('Function instruction sizes',fontsize=8)
plt.legend()
plt.show()
Following is the graph that I get right now.
Maybe you can fit a curve to 'smooth' the curve
import matplotlib.pyplot as plt
x1 = [">1", ">10",">20"]
y1 = [18,8,3]
y2 = [22,15,10]
y3=[32,17,11]
fig = plt.figure()
ax1 = fig.add_subplot(111)
ax1.scatter(x1, y1, color='blue', label='Heuristic')
ax1.scatter(x1, y2, color='green', label='SAFE')
ax1.scatter(x1, y3, color='red', label='discovRE')
buff_x = np.linspace(0,2,100)
def reg_func(y):
params = np.polyfit(range(len(y)),y,2)
return np.polyval(params,buff_x)
plt.plot(buff_x, reg_func(y2), 'g',linestyle='dotted')
plt.plot(buff_x, reg_func(y1), 'b',linestyle='dotted')
plt.plot(buff_x, reg_func(y3), 'r',linestyle='dotted')
plt.ylabel('False Positives',fontsize=8)
plt.xlabel('Function instruction sizes',fontsize=8)
plt.legend()
plt.show()
as you can see, I use a function reg_func to fit your data, and plot the predicted curves

Add Empty Subplot With No Axis Ticks/Labels for Text as Subplot in Matplotlib

My goal is to create plot with four subplots, where the bottom two are really just empty boxes where I will display some text. Unfortunately, all of my efforts to remove the y and x axis tick marks and labels have failed. I'm still new to matplotlib so I'm sure there's something simple that I'm missing. Here's what I'm trying and what I get:
import matplotlib.pyplot as plt
fig, axes = plt.subplots(2, 2, sharex=False, sharey=True, figsize=(6,6))
fig.add_subplot(111, frameon=False)
plt.tick_params(labelcolor='none', top=False, bottom=False, left=False, right=False)
plt.title('Neuron Length')
plt.xlabel('Strain')
plt.ylabel('Neuron Length (um)')
aIP = fig.add_subplot(223, frameon=False)
aIP.annotate('Big Axes \nGridSpec[1:, -1]', (0.1, 0.5),
xycoords='axes fraction', va='center')
# First approach
aIP.axes.xaxis.set_ticks([])
aIP.axes.yaxis.set_ticks([])
# Second approach
ax = plt.gca()
ax.axes.yaxis.set_visible(False)
plt.show()
This is achieved by using plt.subplots() to draw four of them and remove the bottom left frame.
import matplotlib.pyplot as plt
import numpy as np
t = np.linspace(-np.pi, np.pi, 1000)
x1 = np.sin(2*t)
x2 = np.cos(2*t)
x3 = x1 + x2
fig,axes = plt.subplots(nrows=2,ncols=2,figsize=(6,6), sharex=True, sharey=True)
axes[0,0].plot(t, x1, linewidth=2)
axes[0,1].plot(t, x2, linewidth=2)
axes[1,1].plot(t, x3, linewidth=2)
axes[1,0].axis('off') # off
axes[1,0].annotate('Big Axes \nGridSpec[1:, -1]', (0.1, 0.5), xycoords='axes fraction', va='center')
fig.suptitle('Neuron Length')
for ax in axes.flat:
ax.set(xlabel='Strain', ylabel='Neuron Length (um)')
plt.show()

How to Make a secondary vertical axis, with labels on the left, using matplotlib?

I was trying to make a graph with two secondary vertical axis (y-axis), with python matplotlib.
I was using twinx() method, where one of the two new axis is with the default behavior (labels on the right)
and the other with labels on the left, like the example of tan(x) on the figure bellow (created in an specific software).
Is there an easy way to do that? I'm not restricted to use the twinx() method, if there is another way
Here is a way to add two secondary y-axis, one towards the inside:
import numpy as np
import matplotlib.pyplot as plt
x = np.linspace(.5, 10, 1000)
y1 = np.cos(x)
y2 = np.sin(2 * x)
y3 = np.clip(np.tan(x * .6), -75, 75)
fig, ax1 = plt.subplots()
color = 'dodgerblue'
ax1.set_ylabel('$cos(x)$', color=color)
ax1.plot(x, y1, color=color)
ax1.tick_params(axis='y', labelcolor=color)
ax2 = ax1.twinx()
color = 'limegreen'
ax2.set_ylabel('$sin(2 x)$', color=color)
ax2.plot(x, y2, color=color)
ax2.tick_params(axis="y", labelcolor=color)
ax3 = ax1.twinx()
color = 'crimson'
ax3.set_ylabel('$tan(.6 x)$', color=color, labelpad=-40)
ax3.plot(x, y3, color=color)
ax3.tick_params(axis="y", labelcolor=color, direction="in", pad=-5)
plt.setp(ax3.get_yticklabels(), ha="right")
ax1.set_xlim(0, 12)
fig.tight_layout()
plt.show()

Controlling the tracker when using twinx

The tracker in the lower-right corner (highlighted in red) reports y-values relative to the y-axis on the right.
How can I get the tracker to report y-values relative to the y-axis on the left instead?
import matplotlib.pyplot as plt
import numpy as np
np.random.seed(6)
numdata = 100
t = np.linspace(0.05, 0.11, numdata)
y1 = np.cumsum(np.random.random(numdata) - 0.5) * 40000
y2 = np.cumsum(np.random.random(numdata) - 0.5) * 0.002
fig = plt.figure()
ax1 = fig.add_subplot(111)
ax2 = ax1.twinx()
ax1.plot(t, y1, 'r-', label='y1')
ax2.plot(t, y2, 'g-', label='y2')
ax1.legend()
plt.show()
I know swapping y1 with y2 will make the tracker report y1-values,
but this also places the y1 tickmarks on the right-hand side, which is not what I want to happen.
ax1.plot(t, y2, 'g-', label='y2')
ax2.plot(t, y1, 'r-', label='y1')
Ah, found it: ax.yaxis.set_ticks_position("right").
Instead of trying to "control the tracker", you can swap the location of the y-axes.
ax1.yaxis.set_ticks_position("right")
ax2.yaxis.set_ticks_position("left")
ax1.plot(t, y2, 'g-', label='y1')
ax2.plot(t, y1, 'r-', label='y2')
AFAIK, the tracker always follows ax2 when using twinx.
Please note that if you create an ax3= ax1.twiny() axes after ax1 and ax2, the tracker goes to ax3 and you have again it reporting y1 values.
import matplotlib.pyplot as plt
import numpy as np
np.random.seed(6)
numdata = 100
t = np.linspace(0.05, 0.11, numdata)
y1 = np.cumsum(np.random.random(numdata) - 0.5) * 40000
y2 = np.cumsum(np.random.random(numdata) - 0.5) * 0.002
fig = plt.figure()
ax1 = fig.add_subplot(111)
ax2 = ax1.twinx()
ax1.plot(t, y1, 'r-', label='y1')
ax2.plot(t, y2, 'g-', label='y2')
ax1.legend()
ax3 = ax1.twiny()
ax3.set_xticks([])
plt.show()

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