Consider the following code:
import matplotlib.pyplot as plt
import numpy as np
from pylab import *
graph_data = [[0, 1, 2, 3], [5, 8, 7, 9]]
x = range(len(graph_data[0]))
y = graph_data[1]
fig, ax = plt.subplots()
alpha = 0.5
plt.plot(x, y, '-o',markersize=3, color=[1., alpha, alpha], markeredgewidth=0.0)
ax.fill_between(x, 0, y, facecolor=[1., alpha, alpha], interpolate=False)
plt.show()
filename = 'test1.pdf'
fig.savefig(filename, bbox_inches='tight')
It works fine. However, when zoomed in the generated PDF, I can see two thin gray/black boundaries that separate the line:
I can see this when viewing in both Edge and Chrome. My question is, how can I get rid of the boundaries?
UPDATE I forgot to mention, I was using Sage to generate the graph. Now it seems a problem specific to Sage (and not to Python in general). This time I used native Python, and got correct result.
I could not reproduce it but maybe you can try to not plot the line.
import matplotlib.pyplot as plt
import numpy as np
from pylab import *
graph_data = [[0, 1, 2, 3], [5, 8, 7, 9]]
x = range(len(graph_data[0]))
y = graph_data[1]
fig, ax = plt.subplots()
alpha = 0.5
plt.plot(x, y, 'o',markersize=3, color=[1., alpha, alpha])
ax.fill_between(x, 0, y, facecolor=[1., alpha, alpha], interpolate=False)
plt.show()
filename = 'test1.pdf'
fig.savefig(filename, bbox_inches='tight')
Related
Please note, I've looked at other questions like question and my problem is different and not a duplicate!
I would like to have two plots, with the same x axis in matplotlib. I thought this should be achieved via constrained_layout, but apparently this is not the case. Here is an example code.
import pandas as pd
import numpy as np
import seaborn as sns
import matplotlib.pyplot as plt
import matplotlib.gridspec as grd
x = np.arange(0, 30, 0.001)
df_line = pd.DataFrame({"x": x, "y": np.sin(x)})
df_bar = pd.DataFrame({
"x_bar": [1, 7, 10, 20, 30],
"y_bar": [0.0, 0.3, 0.4, 0.1, 0.2]
})
fig = plt.subplots(constrained_layout=True)
gs = grd.GridSpec(2, 1, height_ratios=[3, 2], wspace=0.1)
ax1 = plt.subplot(gs[0])
sns.lineplot(data=df_line, x=df_line["x"], y=df_line["y"], ax=ax1)
ax1.set_xlabel("time", fontsize="22")
ax1.set_ylabel("y values", fontsize="22")
plt.yticks(fontsize=16)
plt.xticks(fontsize=16)
plt.setp(ax1.get_legend().get_texts(), fontsize="22")
ax2 = plt.subplot(gs[1])
sns.barplot(data=df_bar, x="x_bar", y="y_bar", ax=ax2)
ax2.set_xlabel("time", fontsize="22")
ax2.set_ylabel("y values", fontsize="22")
plt.yticks(fontsize=16)
plt.xticks(fontsize=16)
this leads to the following figure.
However, I would like to see the corresponding x values of both plot aligned. How can I achieve this? Note, I've tried to use the following related question. However, this doesn't fully apply to my situation. First with the high number of x points (which I need in reality) point plots is make the picture to big and slow for loading. On top, I can't use the rank method as my categories for the barplot are not evenly distributed. They are specific points on the x axis which should be aligned with the corresponding point on the lineplot
x = np.arange(0, 30, 0.001)
df_line = pd.DataFrame({"x": x, "y": np.sin(x)})
df_bar = pd.DataFrame({
"x_bar": [1, 7, 10, 20, 30],
"y_bar": [0.0, 0.3, 0.4, 0.1, 0.2]
})
fig, (ax1, ax2) = plt.subplots(2,1)
ax1.plot(df_line['x'], df_line['y'])
for i in range(len(df_bar['x_bar'])):
ax2.axvline(x=df_bar['x_bar'][i], ymin=0, ymax=df_bar['y_bar'][i])
Output:
---edit---
I incorporated #mozway advice for linewidth:
lw = (300/ax1.get_xlim()[1])
ax2.axvline(x=df_bar['x_bar'][i], ymin=0, ymax=df_bar['y_bar'][i], solid_capstyle='butt', lw=lw)
Output:
or:
I am trying to export my surface plot into a .png file. For some reason, the saving plot does not correspond to the 3D orientation of the plot showed in spyder. Here is my code:
import csv
import matplotlib.pyplot as plt
from matplotlib import cm
from matplotlib.ticker import LinearLocator
import matplotlib as mpl
import numpy as np
with open(r'path', 'r') as f:
voltpertime = list(csv.reader(f, delimiter=","))
voltpertime = np.array(voltpertime[0:], dtype=np.float)
Z= np.flipud(voltpertime)
fig, ax = plt.subplots(subplot_kw={"projection": "3d"})
# Make data.
X = np.arange(1, 36, 1)
Y = np.arange(-4, 8, 0.1)
X, Y = np.meshgrid(X, Y)
# Plot the surface.
norm = mpl.colors.Normalize(vmin=-0.5, vmax=7)
surf = ax.plot_surface(X, Y, Z, cmap=cm.jet, linewidth=1, antialiased=False, norm=norm)
# Customize the z axis.
ax.set_zlim(-3, 7)
ax.zaxis.set_major_locator(LinearLocator(4))
ax.zaxis.set_major_formatter('{x:.02f}')
plt.colorbar(surf, shrink=0.5, aspect=5, label='current (nA)', pad = 0.1)
plt.yticks((-4, -2, 0, 2, 4, 6, 8), ("8", "6", "4", "2", "0", "-2", "-4"))
# rotate the axes and update
for angle in range(160, 360):
ax.view_init(35, angle)
plt.draw()
plt.pause(.001)
fig.savefig(r'path',
transparent = True, bbox_inches= 'tight', dpi=600, edgecolor= None)
plt.show()
Here is the plot in spyder:
and here is the plot when I save it:
I want to export the plot exactly how it appears in spyder.
Any idea?
Thanks
I have a file 'mydata.tmp' which contains 3 colums like this:
3.81107 0.624698 0.000331622
3.86505 0.624698 0.000131237
3.91903 0.624698 5.15136e-05
3.97301 0.624698 1.93627e-05
1.32802 0.874721 1.59245
1.382 0.874721 1.542
1.43598 0.874721 1.572
1.48996 0.874721 4.27933
etc.
Then I want to make a heatmap color plot where the first two columns are coordinates, and the third column are the values of that coordinates.
Also, I would like to set the third column in log scale.
I have done this
import pandas as pd
import matplotlib.pyplot as plt
import scipy.interpolate
import numpy as np
import matplotlib.colors as colors
# import data
df = pd.read_csv('mydata.tmp', delim_whitespace=True,
comment='#',header=None,
names=['1','2','3'])
x = df['1']
y = df['2']
z = df['3']
spacing = 500
xi, yi = np.linspace(x.min(), x.max(), spacing), np.linspace(y.min(),
y.max(), spacing)
XI, YI = np.meshgrid(xi, yi)
rbf = scipy.interpolate.Rbf(x, y, z, function='linear')
ZI = rbf(XI, YI)
fig, ax = plt.subplots()
sc = ax.imshow(ZI, vmin=z.min(), vmax=z.max(), origin='lower',
extent=[x.min(), x.max(), y.min(),
y.max()], cmap="GnBu", norm=colors.LogNorm(vmin=ZI.min(),
vmax=ZI.max()))
fig.colorbar(sc, ax=ax, fraction=0.05, pad=0.01)
plt.show()
And I get this Image
which has all these empty pixels.
I am looking for something like this instead (I have done this other picture with GNUplot):
How can I do it?
You could use cmap.set_bad to define a color for the NaN values:
import numpy as np
import matplotlib.pyplot as plt
from scipy.interpolate import griddata
import matplotlib.colors as colors
from matplotlib import cm
import copy
# Some data
x = np.array([0, 1, 3, 0, 2, 4])
y = np.array([0, 0, 0, 1, 1, 1])
z = np.array([2, 2, 3, 2, 3, 4])
# Interpolation on a grid:
nrb_points = 101
xi = np.linspace(-.5, 4.5, nrb_points)
yi = np.linspace(-.5, 1.5, nrb_points)
XI, YI = np.meshgrid(xi, yi)
xy = np.vstack((x, y)).T
XY = (XI.ravel(), YI.ravel())
ZI = griddata(points, z, XY,
method='linear',
fill_value=np.nan) # Value used [for] points
# outside of the convex hull
# of the input points.
ZI = ZI.reshape(XI.shape)
# Color map:
cmap = copy.copy(cm.jet)
cmap.set_bad('grey', 1.)
# Graph:
plt.pcolormesh(xi, yi, ZI,
#norm=colors.LogNorm(),
cmap=cmap);
plt.colorbar(label='z');
plt.plot(x, y, 'ko');
plt.xlabel('x'); plt.ylabel('y');
the result is:
I would also use griddata instead of RBF method for the interpolation. Then, point outside the input data area (i.e. the convex hull) can be set to NaN.
How do I generate a line graph in Matplotlib where lines connecting the data points are only vertical and horizontal, not diagonal, giving a "blocky" look?
Note that this is sometimes called zero order extrapolation.
MWE
import matplotlib.pyplot as plt
x = [1, 3, 5, 7]
y = [2, 0, 4, 1]
plt.plot(x, y)
This gives:
and I want:
I think you are looking for plt.step. Here are some examples.
I'm plotting a series of data points with x and y error but do NOT want the errorbars to be included in the legend (only the marker). Is there a way to do so?
Example:
import matplotlib.pyplot as plt
import numpy as np
subs=['one','two','three']
x=[1,2,3]
y=[1,2,3]
yerr=[2,3,1]
xerr=[0.5,1,1]
fig,(ax1)=plt.subplots(1,1)
for i in np.arange(len(x)):
ax1.errorbar(x[i],y[i],yerr=yerr[i],xerr=xerr[i],label=subs[i],ecolor='black',marker='o',ls='')
ax1.legend(loc='upper left', numpoints=1)
fig.savefig('test.pdf', bbox_inches=0)
You can modify the legend handler. See the legend guide of matplotlib.
Adapting your example, this could read:
import matplotlib.pyplot as plt
import numpy as np
subs=['one','two','three']
x=[1,2,3]
y=[1,2,3]
yerr=[2,3,1]
xerr=[0.5,1,1]
fig,(ax1)=plt.subplots(1,1)
for i in np.arange(len(x)):
ax1.errorbar(x[i],y[i],yerr=yerr[i],xerr=xerr[i],label=subs[i],ecolor='black',marker='o',ls='')
# get handles
handles, labels = ax1.get_legend_handles_labels()
# remove the errorbars
handles = [h[0] for h in handles]
# use them in the legend
ax1.legend(handles, labels, loc='upper left',numpoints=1)
plt.show()
This produces
Here is an ugly patch:
pp = []
colors = ['r', 'b', 'g']
for i, (y, yerr) in enumerate(zip(ys, yerrs)):
p = plt.plot(x, y, '-', color='%s' % colors[i])
pp.append(p[0])
plt.errorbar(x, y, yerr, color='%s' % colors[i])
plt.legend(pp, labels, numpoints=1)
Here is a figure for example:
The accepted solution works in simple cases but not in general. In particular, it did not work in my own more complex situation.
I found a more robust solution, which tests for ErrorbarContainer, which did work for me. It was proposed by Stuart W D Grieve and I copy it here for completeness
import matplotlib.pyplot as plt
from matplotlib import container
label = ['one', 'two', 'three']
color = ['red', 'blue', 'green']
x = [1, 2, 3]
y = [1, 2, 3]
yerr = [2, 3, 1]
xerr = [0.5, 1, 1]
fig, (ax1) = plt.subplots(1, 1)
for i in range(len(x)):
ax1.errorbar(x[i], y[i], yerr=yerr[i], xerr=xerr[i], label=label[i], color=color[i], ecolor='black', marker='o', ls='')
handles, labels = ax1.get_legend_handles_labels()
handles = [h[0] if isinstance(h, container.ErrorbarContainer) else h for h in handles]
ax1.legend(handles, labels)
plt.show()
It produces the following plot (on Matplotlib 3.1)
I works for me if I set the label argument as a None type.
plt.errorbar(x, y, yerr, label=None)