I am using the below codes to quantise the input signal for quantisation interval of 0.5 and this should give me staircase signal.The algorithm used here is same as used in Simulink.Could any one help me plot the quantised signal.
import numpy as np
import matplotlib.pyplot as plt
for i in range(0,10):
q=0.5;
x=q*np.round(i/q);
plt.plot(i,x)
plt.xlim([0,10])
plt.ylim([0,10])
plt.hold()
plt.grid()
plt.show()
Do you mean something like this?
import numpy as np
import matplotlib.pyplot as plt
q = 0.5
x = np.linspace(0, 10, 1000)
y = q * np.round(x/q)
plt.plot(x,y)
Related
I'm trying to print a logistic differential equation and I'm pretty sure the equation is written correctly but my graph doesn't display anything.
import matplotlib as mpl
import matplotlib.pyplot as plt
import numpy as np
def eq(con,x):
return con*x*(1-x)
xList = np.linspace(0,4, num=1000)
con = 2.6
x= .4
for num in range(len(xList)-1):
plt.plot(xList[num], eq(con,x))
x=eq(con,x)
plt.xlabel('Time')
plt.ylabel('Population')
plt.title("Logistic Differential Equation")
plt.show()
You get nothing in your plot because you are plotting points.
In plt you need to have x array and y array (that have the same length) in order to make a plot.
If you want to do exactly what you are doing I suggest to do like this:
import matplotlyb.pyplot as plt # just plt is sufficent
import numpy as np
def eq(con,x):
return con*x*(1-x)
xList = np.linspace(0,4, num=1000)
con = 2.6
x= .4
y = np.zeros(len(xList)) # initialize an array with the same lenght as xList
for num in range(len(xList)-1):
y[num] = eq(con,x)
x=eq(con,x)
plt.figure() # A good habit is always to use figures in plt
plt.plot(xList, y) # 2 arrays of the same lenght
plt.xlabel('Time')
plt.ylabel('Population')
plt.title("Logistic Differential Equation")
plt.show() # now you should get somthing here
I hope that this helps you ^^
I have some lists that each of which has a different shape and I would like to plot all of them together in one polar scatter plot. I also tried to use iter tools but I could not find the solution.
import numpy as np
import matplotlib.pyplot as plt
a1=[1,2,3,4,5,6]
a2=[2,3,5,6]
a3=[1,2,3]
a4=[1,2,3,4,4,56,7,8]
ax1 = plt.subplot(111,polar= True)
for i in range (0,3):
theta = 4 * np.pi * np.random.rand(len(a[i]))
ax1.set_ylim(0,0.1)
ax1.set_rlabel_position(180)
for i in range (0,3):
ax1.scatter(theta,a[i], cmap='hsv', alpha=0.5)
Be carefull i modified your lists for a better visual exmaple!
I hope I understood your question correctly...
import numpy as np
import matplotlib.pyplot as plt
a1=[1,2,3,4,5,6]
a2=[2,3,5,6]
a3=[1,2,3]
a4=[1,2,3,4,4,7,7,8]
ax1 = plt.subplot(111,polar= True)
for onelist in [a1,a2,a3,a4]:
theta_list = np.linspace(0,2*np.pi,len(onelist))
ax1.plot(theta_list,onelist,marker="x")
plt.show()
Original(2018.11.01)
I have 3 numpy：x、y、z,created by my laser scanner(40 degree / 1 step).
I want to used them to build a 3D model.
I think it must should be use matplotlib.tri
But I have no idea to decide triangulated data
Here is my data ：https://www.dropbox.com/s/d9p62kv9jcq9bwh/xyz.zip?dl=0
And Original model：https://i.imgur.com/XSyONff.jpg
Code：
import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D
import matplotlib.tri as mtri
x_all=np.load("x.npy")
y_all=np.load("y.npy")
z_all=np.load("z.npy")
tri = #I have no idea...
fig = plt.figure()
ax = fig.gca(projection='3d')
ax.plot_trisurf(x_all,y_all,z_all,triangles=tri.triangles)
Thank so much.
Update(2018.11.02)
I try this way to decide triangulated data
Delaunay Triangulation of points from 2D surface in 3D with python?
code:
import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D
import matplotlib.tri as mtri
from stl import mesh
x_all=np.load("x.npy")
y_all=np.load("y.npy")
z_all=np.load("z.npy")
model=np.vstack((x_all,y_all,z_all))
model=np.transpose(model)
model -= model.mean(axis=0)
rad = np.linalg.norm(model, axis=1)
zen = np.arccos(model[:,-1] / rad)
azi = np.arctan2(model[:,1], model[:,0])
tris = mtri.Triangulation(zen, azi)
plt.show()
And my model looks like:
https://i.stack.imgur.com/KVPHP.png
https://i.stack.imgur.com/LLQsQ.png
https://i.stack.imgur.com/HdzFm.png
Even though it has better surface on it,but there is a big hole over my model.Any idea to fixs it?
Assuming you want to reduce the complexity, i.e find triangles in your files to reduce the complexity. You may look into fitting a convex hull to your points, see here fore more info
Based on the file you provided this produces a surf plot of the object.
from numpy import load, stack
from matplotlib.pyplot import subplots
from mpl_toolkits.mplot3d import Axes3D
from scipy import spatial
x = load("x.npy")
y = load("y.npy")
z = load("z.npy")
points = stack((x,y,z), axis = -1)
v = spatial.ConvexHull(points)
fig, ax = subplots(subplot_kw = dict(projection = '3d'))
ax.plot_trisurf(*v.points.T, triangles = v.simplices.T)
fig.show()
Python (and matplotlib) newbie here coming over from R, so I hope this question is not too idiotic. I'm trying to make a loglog plot on a natural log scale. But after some googling I cannot somehow figure out how to force pyplot to use a base e scale on the axes. The code I have currently:
import matplotlib.pyplot as pyplot
import math
e = math.exp(1)
pyplot.loglog(range(1,len(degrees)+1),degrees,'o',basex=e,basey=e)
Where degrees is a vector of counts at each value of range(1,len(degrees)+1). For some reason when I run this code, pyplot keeps giving me a plot with powers of 2 on the axes. I feel like this ought to be easy, but I'm stumped...
Any advice is greatly appreciated!
When plotting using plt.loglog you can pass the keyword arguments basex and basey as shown below.
From numpy you can get the e constant with numpy.e (or np.e if you import numpy as np)
import numpy as np
import matplotlib.pyplot as plt
# Generate some data.
x = np.linspace(0, 2, 1000)
y = x**np.e
plt.loglog(x,y, basex=np.e, basey=np.e)
plt.show()
Edit
Additionally if you want pretty looking ticks you can use matplotlib.ticker to choose the format of your ticks, an example of which is given below.
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.ticker as mtick
x = np.linspace(1, 4, 1000)
y = x**3
fig, ax = plt.subplots()
ax.loglog(x,y, basex=np.e, basey=np.e)
def ticks(y, pos):
return r'$e^{:.0f}$'.format(np.log(y))
ax.xaxis.set_major_formatter(mtick.FuncFormatter(ticks))
ax.yaxis.set_major_formatter(mtick.FuncFormatter(ticks))
plt.show()
It can also works for semilogx and semilogy to show them in e and also change their name.
import matplotlib.ticker as mtick
fig, ax = plt.subplots()
def ticks(y, pos):
return r'$e^{:.0f}$'.format(np.log(y))
plt.semilogy(Time_Series, California_Pervalence ,'gray', basey=np.e )
ax.yaxis.set_major_formatter(mtick.FuncFormatter(ticks))
plt.show()
Take a look at the image.
So I made a program that does what I need, mainly plots histogram from my data, but I have a few issues with it:
Here's the program:
# -*- coding: cp1250 -*-
from __future__ import division
from numpy import *
from matplotlib import rc
from matplotlib.pyplot import *
import numpy as np
import matplotlib.pyplot as plt
data = loadtxt("mioni.txt", int)
nuz = len(data)
nsmp = 20
duz = int(nuz/nsmp)
L = []
for i1 in range(0,nsmp):
suma = 0
for i2 in range(0,duz):
suma += data[i1*duz+i2]
L.append(suma)
print L
plt.hist(L, 20, normed=1, facecolor='blue', alpha=0.75)
plt.xlabel('t(\mu s)')
plt.ylabel('Broj događaja')
plt.axis([0,10,0,300])
plt.grid(True)
plt.show()
EDIT: so I managed to deal with the ugly sums, but now my histograms don't work :(
Data is here: http://dropcanvas.com/kqjem
What's wrong? I get tons of errors and python crashes :\
The problem comes from having a discrete data set, it looks like you set the bins parameter to something that doesn't fit. Use the pylab.hist parameter histtype="stepfilled" to get them to touch without the lines. Here are a few examples:
import numpy as np
import pylab as plt
# Sample data
X1 = np.random.exponential(1.0,size=5000)
X2 = [int(z) for z in X1]
plt.subplot(221)
plt.hist(X1,bins=50)
plt.title('Continuous Data')
plt.subplot(222)
plt.hist(X2,bins=50)
plt.title('Discrete Data')
plt.subplot(223)
plt.hist(X2,histtype='stepfilled')
plt.title('Discrete Data Filled')
plt.show()
use numpy.histogram: http://docs.scipy.org/doc/numpy/reference/generated/numpy.histogram.html
or matplotlib.pyplot.hist: http://matplotlib.org/api/pyplot_api.html#matplotlib.pyplot.hist
for example:
plt.hist(data, bins=20)