我试图使用matplotlib.pyplot.imshow()显示灰度图像。我的问题是灰度图像显示为色图。我需要它是灰度的，因为我想在图像上画上颜色。
我在图像中读取并使用PIL的image .open().convert(“L”)转换为灰度
image = Image.open(file).convert("L")
然后我将图像转换为一个矩阵，这样我就可以很容易地使用一些图像处理
matrix = scipy.misc.fromimage(image, 0)
然而，当我这样做的时候
figure()
matplotlib.pyplot.imshow(matrix)
show()
它使用色图显示图像(即它不是灰度)。
我哪里做错了?
我试图保存我使用matplotlib的情节;然而，图像是空白保存。
这是我的代码:
plt.subplot(121)
plt.imshow(dataStack, cmap=mpl.cm.bone)
plt.subplot(122)
y = copy.deepcopy(tumorStack)
y = np.ma.masked_where(y == 0, y)
plt.imshow(dataStack, cmap=mpl.cm.bone)
plt.imshow(y, cmap=mpl.cm.jet_r, interpolation='nearest')
if T0 is not None:
plt.subplot(123)
plt.imshow(T0, cmap=mpl.cm.bone)
#plt.subplot(124)
#Autozoom
#else:
#plt.subplot(124)
#Autozoom
plt.show()
plt.draw()
plt.savefig('tessstttyyy.png', dpi=100)
tessstttyyy.png是空白的(也尝试用。jpg)
如何使用subprocess.call()获得进程运行的输出?
传递一个StringIO。StringIO对象的stdout给出以下错误:
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/subprocess.py", line 444, in call
return Popen(*popenargs, **kwargs).wait()
File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/subprocess.py", line 588, in __init__
errread, errwrite) = self._get_handles(stdin, stdout, stderr)
File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/subprocess.py", line 945, in _get_handles
c2pwrite = stdout.fileno()
AttributeError: StringIO instance has no attribute 'fileno'
>>>
在matplotlib中有哪些命名颜色可用于绘图?我可以在matplotlib文档中找到一个列表，声称这些是唯一的名称:
b: blue
g: green
r: red
c: cyan
m: magenta
y: yellow
k: black
w: white
然而，我发现这些颜色也可以使用，至少在这种情况下:
scatter(X,Y, color='red')
scatter(X,Y, color='orange')
scatter(X,Y, color='darkgreen')
但这些都不在上面的清单上。有没有人知道可供选择的已命名颜色的详尽列表?
我花了太长时间研究如何在Matplotlib中让两个子图共享相同的y轴，并在两者之间共享一个颜色条。
发生的事情是，当我在subplot1或subplot2中调用colorbar()函数时，它会自动缩放图形，以便颜色条加上图形将适合'subplot'边界框，导致两个并排的图形具有两个非常不同的大小。
为了解决这个问题，我试着创建了第三个子图，然后我把它黑了，只渲染一个颜色条。 唯一的问题是，现在两个地块的高度和宽度不均匀，我不知道如何让它看起来还好。
这是我的代码:
from __future__ import division
import matplotlib.pyplot as plt
import numpy as np
from matplotlib import patches
from matplotlib.ticker import NullFormatter
# SIS Functions
TE = 1 # Einstein radius
g1 = lambda x,y: (TE/2) * (y**2-x**2)/((x**2+y**2)**(3/2))
g2 = lambda x,y: -1*TE*x*y / ((x**2+y**2)**(3/2))
kappa = lambda x,y: TE / (2*np.sqrt(x**2+y**2))
coords = np.linspace(-2,2,400)
X,Y = np.meshgrid(coords,coords)
g1out = g1(X,Y)
g2out = g2(X,Y)
kappaout = kappa(X,Y)
for i in range(len(coords)):
for j in range(len(coords)):
if np.sqrt(coords[i]**2+coords[j]**2) <= TE:
g1out[i][j]=0
g2out[i][j]=0
fig = plt.figure()
fig.subplots_adjust(wspace=0,hspace=0)
# subplot number 1
ax1 = fig.add_subplot(1,2,1,aspect='equal',xlim=[-2,2],ylim=[-2,2])
plt.title(r"$\gamma_{1}$",fontsize="18")
plt.xlabel(r"x ($\theta_{E}$)",fontsize="15")
plt.ylabel(r"y ($\theta_{E}$)",rotation='horizontal',fontsize="15")
plt.xticks([-2.0,-1.5,-1.0,-0.5,0,0.5,1.0,1.5])
plt.xticks([-2.0,-1.5,-1.0,-0.5,0,0.5,1.0,1.5])
plt.imshow(g1out,extent=(-2,2,-2,2))
plt.axhline(y=0,linewidth=2,color='k',linestyle="--")
plt.axvline(x=0,linewidth=2,color='k',linestyle="--")
e1 = patches.Ellipse((0,0),2,2,color='white')
ax1.add_patch(e1)
# subplot number 2
ax2 = fig.add_subplot(1,2,2,sharey=ax1,xlim=[-2,2],ylim=[-2,2])
plt.title(r"$\gamma_{2}$",fontsize="18")
plt.xlabel(r"x ($\theta_{E}$)",fontsize="15")
ax2.yaxis.set_major_formatter( NullFormatter() )
plt.axhline(y=0,linewidth=2,color='k',linestyle="--")
plt.axvline(x=0,linewidth=2,color='k',linestyle="--")
plt.imshow(g2out,extent=(-2,2,-2,2))
e2 = patches.Ellipse((0,0),2,2,color='white')
ax2.add_patch(e2)
# subplot for colorbar
ax3 = fig.add_subplot(1,1,1)
ax3.axis('off')
cbar = plt.colorbar(ax=ax2)
plt.show()
我正在使用pyplot。我有4个子情节。如何将一个单一的主标题置于所有次要情节之上?Title()将其设置在最后一个子情节之上。
我试图显示一个复选标记，如果一个答案是接受的答案:
template: `<div ngIf="answer.accepted">✔</div>`
但是我得到了这个错误:
EXCEPTION: No provider for TemplateRef! (NgIf ->TemplateRef)
我做错了什么?
我有一个具有大量特征的数据集，因此分析相关矩阵变得非常困难。我想绘制一个相关矩阵，我们使用dataframe.corr()函数从pandas库中获得。pandas库是否提供了任何内置函数来绘制这个矩阵?
我试着用Python使用networkx。当我运行这个程序时，它得到这个错误。少了什么东西吗?
#!/usr/bin/env python
import networkx as nx
import matplotlib
import matplotlib.pyplot
import matplotlib.pyplot as plt
G=nx.Graph()
G.add_node(1)
G.add_nodes_from([2,3,4,5,6,7,8,9,10])
#nx.draw_graphviz(G)
#nx_write_dot(G, 'node.png')
nx.draw(G)
plt.savefig("/var/www/node.png")
Traceback (most recent call last):
File "graph.py", line 13, in <module>
nx.draw(G)
File "/usr/lib/pymodules/python2.5/networkx/drawing/nx_pylab.py", line 124, in draw
cf=pylab.gcf()
File "/usr/lib/pymodules/python2.5/matplotlib/pyplot.py", line 276, in gcf
return figure()
File "/usr/lib/pymodules/python2.5/matplotlib/pyplot.py", line 254, in figure
**kwargs)
File "/usr/lib/pymodules/python2.5/matplotlib/backends/backend_tkagg.py", line 90, in new_figure_manager
window = Tk.Tk()
File "/usr/lib/python2.5/lib-tk/Tkinter.py", line 1650, in __init__
self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
_tkinter.TclError: no display name and no $DISPLAY environment variable
我现在得到一个不同的错误:
#!/usr/bin/env python
import networkx as nx
import matplotlib
import matplotlib.pyplot
import matplotlib.pyplot as plt
matplotlib.use('Agg')
G=nx.Graph()
G.add_node(1)
G.add_nodes_from([2,3,4,5,6,7,8,9,10])
#nx.draw_graphviz(G)
#nx_write_dot(G, 'node.png')
nx.draw(G)
plt.savefig("/var/www/node.png")
/usr/lib/pymodules/python2.5/matplotlib/__init__.py:835: UserWarning: This call to matplotlib.use() has no effect
because the the backend has already been chosen;
matplotlib.use() must be called *before* pylab, matplotlib.pyplot,
or matplotlib.backends is imported for the first time.
if warn: warnings.warn(_use_error_msg)
Traceback (most recent call last):
File "graph.py", line 15, in <module>
nx.draw(G)
File "/usr/lib/python2.5/site-packages/networkx-1.2.dev-py2.5.egg/networkx/drawing/nx_pylab.py", line 124, in draw
cf=pylab.gcf()
File "/usr/lib/pymodules/python2.5/matplotlib/pyplot.py", line 276, in gcf
return figure()
File "/usr/lib/pymodules/python2.5/matplotlib/pyplot.py", line 254, in figure
**kwargs)
File "/usr/lib/pymodules/python2.5/matplotlib/backends/backend_tkagg.py", line 90, in new_figure_manager
window = Tk.Tk()
File "/usr/lib/python2.5/lib-tk/Tkinter.py", line 1650, in __init__
self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
_tkinter.TclError: no display name and no $DISPLAY environment variable
我现在得到一个不同的错误:
#!/usr/bin/env python
import networkx as nx
import matplotlib
import matplotlib.pyplot
import matplotlib.pyplot as plt
matplotlib.use('Agg')
G=nx.Graph()
G.add_node(1)
G.add_nodes_from([2,3,4,5,6,7,8,9,10])
#nx.draw_graphviz(G)
#nx_write_dot(G, 'node.png')
nx.draw(G)
plt.savefig("/var/www/node.png")
/usr/lib/pymodules/python2.5/matplotlib/__init__.py:835: UserWarning: This call to matplotlib.use() has no effect
because the the backend has already been chosen;
matplotlib.use() must be called *before* pylab, matplotlib.pyplot,
or matplotlib.backends is imported for the first time.
if warn: warnings.warn(_use_error_msg)
Traceback (most recent call last):
File "graph.py", line 15, in <module>
nx.draw(G)
File "/usr/lib/python2.5/site-packages/networkx-1.2.dev-py2.5.egg/networkx/drawing/nx_pylab.py", line 124, in draw
cf=pylab.gcf()
File "/usr/lib/pymodules/python2.5/matplotlib/pyplot.py", line 276, in gcf
return figure()
File "/usr/lib/pymodules/python2.5/matplotlib/pyplot.py", line 254, in figure
**kwargs)
File "/usr/lib/pymodules/python2.5/matplotlib/backends/backend_tkagg.py", line 90, in new_figure_manager
window = Tk.Tk()
File "/usr/lib/python2.5/lib-tk/Tkinter.py", line 1650, in __init__
self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
_tkinter.TclError: no display name and no $DISPLAY environment variable
我正在尝试使用OpenCV实时绘制来自摄像机的一些数据。但是，实时绘图(使用matplotlib)似乎不能正常工作。
我把这个问题隔离在这个简单的例子中:
fig = plt.figure()
plt.axis([0, 1000, 0, 1])
i = 0
x = list()
y = list()
while i < 1000:
temp_y = np.random.random()
x.append(i)
y.append(temp_y)
plt.scatter(i, temp_y)
i += 1
plt.show()
我希望这个例子能分别画出1000个点。实际发生的情况是，窗口弹出，显示第一个点(好吧)，然后等待循环结束，然后填充图的其余部分。
有什么想法，为什么我没有看到点填充一个时间?