The code below produces the plot and legend correctly, however the legend does not show the specified label text, but "Container object of 10 artists" instead.
ax = plt.subplot(212)
plt.tight_layout()
l1= plt.bar(X+0.25, Y1, 0.45, align='center', color='r', label='A', edgecolor='black', hatch="/")
l2= plt.bar(X, Y2, 0.45, align='center', color='b', label='N',hatch='o', fill=False)
ax.autoscale(tight=True)
plt.xticks(X, X_values)
ymax1 = max(Y1) + 1
ymax2 = max(Y2) + 1
ymax = max(ymax1,ymax2)+1
plt.ylim(0, ymax)
plt.grid(True)
plt.legend([l1,l2], loc='upper right', prop={'size':20})
The output is shown below:
How can I correctly display the labels for each bar (as specified in the plt.bar() function) on the legend?
The problem stems from mixing two approaches to using plt.legend(). You have two options:
Manually specify the labels for the legend
Use ax.get_legend_handles_labels() to fill them in with the label parameters you passed to plt.bar()
To manually specify the labels, pass them as the second argument to your call to plt.legend() as follows:
plt.legend([l1,l2], ["A", "N"], loc='upper right', prop={'size':20})
If instead you want to automatically populate the legend you can use the following to find legend-able objects in the plot and their labels:
handles, labels = ax.get_legend_handles_labels()
ax.legend(handles, labels, loc='upper right', prop={'size':20})
Related
I'm trying to plot multiple things in a figure with subplots.
When I try generating a legend for the figure, it is only showing labels for the data in the very last subplot, instead of for the entire figure.
fig, axs = plt.subplots(3, 2, figsize=(16,18))
first_pops = {"M71 (Masseron)":[1., "purple"], \
"6273 (Yong)":[0.1, "yellowgreen"], \
"2419 (Carretta)":[0.0, "olive"], \
"6218 (Carretta)":[0.25, "darkcyan"],
}
elements = ["O I", "Na I", "Mg I", "Si I", "Ti I", "Ca I"]
element_labels = ["[O/Fe]", "[Na/Fe]", "[Mg/Fe]", "[Si/Fe]", "[Ti/Fe]", "[Ca/Fe]"]
for k, ax in enumerate(axs.ravel()):
element = elements[k]
element_label = element_labels[k]
for GC in first_pops.keys():
try:
plot_background_stars(glob_dict[GC]["[Fe/H]"],\
glob_dict[GC][element_label],\
label = GC, ax=ax, color = first_pops[GC][1],\
s = 140, marker="*", facecolors='none', linewidth=2)
except KeyError:
print(GC+" doesn't have "+element+" measured")
ax.set_xlabel("[Fe/H]")
ax.set_ylabel(element_label)
handles, labels = fig.gca().get_legend_handles_labels()
by_label = dict(zip(labels, handles))
fig.legend(by_label.values(), by_label.keys())
I've tried replacing "fig" with "plt" and vice versa.
I'm using the following to plot each data set:
def plot_background_stars(x, y, ax=None, **plt_kwargs):
if ax is None:
ax = plt.gca()
ax.scatter(x, y, **plt_kwargs)
return(ax)
The resulting legend has just two of the plotted colors, instead of four. Like maybe it's only pulling the labels from the last subplot? But why would it do that?
I need example to make customize ticklabel (label inside box), like bid price in MetaTrader platform
You can put use ax.annotate to put a text with a bbox there.
Like:
fig, ax = plt.subplots()
# Do the plotting
# Set the ylim for this example
ax.set(ylim=(104, 106))
# Get the xlim
right = ax.get_xlim()[1]
# Put the text
ax.annotate('105.252', (right, 105.252), (3, 0),
textcoords='offset points',
ha='left', va='center', color='w',
bbox=dict(facecolor='#26a69a', edgecolor='none', pad=.1))
The following code is for generating the 3 subplots. And on all the 3 subplots scale is mentioned. I want to stack them in such a way that x-axis and y-axis scale appear once like this. Can I get this plot with plt.subplot() or fig.add_axes is compulsory for this? I actually want to do this with subplots because in fig.add_subplot I havve to specify the width and height of each plot that I don't want.
`fig,axes = plt.figure(nrow=3, ncolmn=1)
ax1 = fig.add_subplot(311)
ax2 = fig.add_subplot(312)
ax3 = fig.add_subplot(313)
ind1 =[1,2,3]
ind2 = [4,5,6]
for i in range(len(3)):
data1=np.load(..)
data2=np.load(..)
axes[i].plot(data1, data2)`
Here is one solution using subplots_adjust where you put the space between two plots to 0 using hspace. Also, use sharex=True to have a shared x-axis
fig, axes = plt.subplots(nrows=3, ncols=1,sharex=True)
x = np.linspace(0, 2*np.pi, 100)
y = np.sin(x)
for i, ax in enumerate(axes.ravel()): # or axes.flatten() or axes.flat
ax.plot(x, y, label='File %d' %i)
ax.legend()
fig.text(0.5, 0.01, 'X-label', ha='center')
fig.text(0.01, 0.5, 'Y-label', va='center', rotation='vertical')
plt.tight_layout() # To get a better spacing between the subplots
plt.subplots_adjust(hspace=.0)
I'm trying to add a legend to a matplotlib radar/polar graph. I am very new to matplotlib so please excuse the code. I also expect this is very simple but I've been at it an hour and got nowhere.
I have the following which produces a list of labels in the bottom left corner but whenever I try to add handles to give the color representing the label I lose the legend.
# Set color of axes
plt.rc('axes', linewidth=0.5, edgecolor="#888888")
# Create polar plot
ax = plt.subplot(111, polar=True)
# Set clockwise rotation. That is:
ax.set_theta_offset(pi / 2)
ax.set_theta_direction(-1)
# Set position of y-labels
ax.set_rlabel_position(0)
# Set color and linestyle of grid
ax.xaxis.grid(True, color="#888888", linestyle='solid', linewidth=0.5)
ax.yaxis.grid(True, color="#888888", linestyle='solid', linewidth=0.5)
# Plot data
ax.plot(x_as, values, linewidth=0, linestyle='solid', zorder=3)
# Fill area
ax.fill(x_as, values, 'r', alpha=0.3)
plt.legend(labels=[self.get_object().name], loc=(-.42,-.13))
if not self.get_object().subscription is None:
if self.get_object().subscription.benchmark:
bx = plt.subplot(111, polar=True)
bx.plot(x_as, baseline, linewidth=0, linestyle='solid', zorder=3)
bx.fill(x_as, baseline, 'b', alpha=0.3)
plt.legend(labels=[self.get_object().name, 'Benchmark'], loc=(-.42,-.13))
I believe I need
plt.lengend(handles=[some list], labels=[self.get_object().name, 'Benchmark'], loc=(-.42,-.13))
I do not understand what the list of handles should be and I've tried a number of things, including [ax, bx], [ax.plt(), bx.plt()], ['r', 'b']
From the documentation:
handles : sequence of Artist, optional
A list of Artists (lines, patches) to be added to the legend. Use this together with labels, if you need full control on what is shown
in the legend and the automatic mechanism described above is not
sufficient.
The length of handles and labels should be the same in this case. If they are not, they are truncated to the smaller length.
plt.plot returns a list a line2D objects which is what you need to pass to plt.legend(). Therefore a simplified example is as follows:
labels = ["Line 1", "Line 2"]
lines1, = plt.plot([1,2,3])
lines2, = plt.plot([3,2,1])
handles = [lines1, lines2]
plt.legend(handles, labels)
plt.show()
I am trying to make some figures for a scientific article, so I want my figures to have a specific size. I also see that Matplotlib by default adds a lot of padding on the border of the figures, which I don't need (since the figures will be on a white background anyway).
To set a specific figure size I simply use plt.figure(figsize = [w, h]), and I add the argument tight_layout = {'pad': 0} to remove the padding. This works perfectly, and even works if I add a title, y/x-labels etc. Example:
fig = plt.figure(
figsize = [3,2],
tight_layout = {'pad': 0}
)
ax = fig.add_subplot(111)
plt.title('title')
ax.set_ylabel('y label')
ax.set_xlabel('x label')
plt.savefig('figure01.pdf')
This creates a pdf file with exact size 3x2 (inches).
The issue I have is that when I for example add a text box outside the axis (typically a legend box), Matplotlib does not make room for the text box like it does when adding titles/axis labels. Typically the text box is cut off, or does not show in the saved figure at all. Example:
plt.close('all')
fig = plt.figure(
figsize = [3,2],
tight_layout = {'pad': 0}
)
ax = fig.add_subplot(111)
plt.title('title')
ax.set_ylabel('y label')
ax.set_xlabel('x label')
t = ax.text(0.7, 1.1, 'my text here', bbox = dict(boxstyle = 'round'))
plt.savefig('figure02.pdf')
A solution I found elsewhere on SO was to add the argument bbox_inches = 'tight' to the savefig command. The text box is now included like I wanted, but the pdf is now the wrong size. It seems like Matplotlib just makes the figure bigger, instead of reducing the size of the axes like it does when adding titles and x/y-labels.
Example:
plt.close('all')
fig = plt.figure(
figsize = [3,2],
tight_layout = {'pad': 0}
)
ax = fig.add_subplot(111)
plt.title('title')
ax.set_ylabel('y label')
ax.set_xlabel('x label')
t = ax.text(0.7, 1.1, 'my text here', bbox = dict(boxstyle = 'round'))
plt.savefig('figure03.pdf', bbox_inches = 'tight')
(This figure is 3.307x2.248)
Is there any solution to this that covers most cases with a legend just outside the axes?
So the requirements are:
Having a fixed, predefined figure size
Adding a text label or legend outside the axes
Axes and text cannot overlap
The axes, together with the title and axis labels, sits tightly agains the figure border.
So tight_layout with pad = 0, solves 1. and 4. but contradicts 2.
One could think on setting pad to a larger value. This would solve 2. However, since it's is symmetric in all directions, it would contradict 4.
Using bbox_inches = 'tight' changes the figure size. Contradicts 1.
So I think there is no generic solution to this problem.
Something I can come up with is the following: It sets the text in figure coordinates and then resizes the axes either in horizontal or in vertical direction such that there is no overlap between the axes and the text.
import matplotlib.pyplot as plt
import matplotlib.transforms
fig = plt.figure(figsize = [3,2])
ax = fig.add_subplot(111)
plt.title('title')
ax.set_ylabel('y label')
ax.set_xlabel('x label')
def text_legend(ax, x0, y0, text, direction = "v", padpoints = 3, margin=1.,**kwargs):
ha = kwargs.pop("ha", "right")
va = kwargs.pop("va", "top")
t = ax.figure.text(x0, y0, text, ha=ha, va=va, **kwargs)
otrans = ax.figure.transFigure
plt.tight_layout(pad=0)
ax.figure.canvas.draw()
plt.tight_layout(pad=0)
offs = t._bbox_patch.get_boxstyle().pad * t.get_size() + margin # adding 1pt
trans = otrans + \
matplotlib.transforms.ScaledTranslation(-offs/72.,-offs/72.,fig.dpi_scale_trans)
t.set_transform(trans)
ax.figure.canvas.draw()
ppar = [0,-padpoints/72.] if direction == "v" else [-padpoints/72.,0]
trans2 = matplotlib.transforms.ScaledTranslation(ppar[0],ppar[1],fig.dpi_scale_trans) + \
ax.figure.transFigure.inverted()
tbox = trans2.transform(t._bbox_patch.get_window_extent())
bbox = ax.get_position()
if direction=="v":
ax.set_position([bbox.x0, bbox.y0,bbox.width, tbox[0][1]-bbox.y0])
else:
ax.set_position([bbox.x0, bbox.y0,tbox[0][0]-bbox.x0, bbox.height])
# case 1: place text label at top right corner of figure (1,1). Adjust axes height.
#text_legend(ax, 1,1, 'my text here', bbox = dict(boxstyle = 'round'), )
# case 2: place text left of axes, (1, y), direction=="v"
text_legend(ax, 1., 0.8, 'my text here', margin=2., direction="h", bbox = dict(boxstyle = 'round') )
plt.savefig(__file__+'.pdf')
plt.show()
case 1 (left) and case 2 (right):
Doin the same with a legend is slightly easier, because we can directly use the bbox_to_anchor argument and don't need to control the fancy box around the legend.
import matplotlib.pyplot as plt
import matplotlib.transforms
fig = plt.figure(figsize = [3.5,2])
ax = fig.add_subplot(111)
ax.set_title('title')
ax.set_ylabel('y label')
ax.set_xlabel('x label')
ax.plot([1,2,3], marker="o", label="quantity 1")
ax.plot([2,1.7,1.2], marker="s", label="quantity 2")
def legend(ax, x0=1,y0=1, direction = "v", padpoints = 3,**kwargs):
otrans = ax.figure.transFigure
t = ax.legend(bbox_to_anchor=(x0,y0), loc=1, bbox_transform=otrans,**kwargs)
plt.tight_layout(pad=0)
ax.figure.canvas.draw()
plt.tight_layout(pad=0)
ppar = [0,-padpoints/72.] if direction == "v" else [-padpoints/72.,0]
trans2=matplotlib.transforms.ScaledTranslation(ppar[0],ppar[1],fig.dpi_scale_trans)+\
ax.figure.transFigure.inverted()
tbox = t.get_window_extent().transformed(trans2 )
bbox = ax.get_position()
if direction=="v":
ax.set_position([bbox.x0, bbox.y0,bbox.width, tbox.y0-bbox.y0])
else:
ax.set_position([bbox.x0, bbox.y0,tbox.x0-bbox.x0, bbox.height])
# case 1: place text label at top right corner of figure (1,1). Adjust axes height.
#legend(ax, borderaxespad=0)
# case 2: place text left of axes, (1, y), direction=="h"
legend(ax,y0=0.8, direction="h", borderaxespad=0.2)
plt.savefig(__file__+'.pdf')
plt.show()
Why 72? The 72 is the number of points per inch (ppi). This is a fixed typographic unit e.g. fontsizes are always given in points (like 12pt). Because matplotlib defines the padding of the text box in units relative to fontsize, which is points, we need to use 72 to transform back to inches (and then to display coordinates). The default dots per inch (dpi) is not touched here, but is accounted for in fig.dpi_scale_trans. If you want to change dpi you need to make sure the figure dpi is set when creating the figure as well as when saving it (use dpi=.. in the call to plt.figure() as well as plt.savefig()).
As of matplotlib==3.1.3, you can use constrained_layout=True to achieve the desired result. This is currently experimental, but see the docs for a very helpful guide (and the section specifically on legends). Note that the legend will steal space from the plot, but this is unavoidable. I've found that as long as the legend does not take up too much space relative to the size of the plot, then the figure gets saved without cropping anything.
import matplotlib.pyplot as plt
fig, ax = plt.subplots(figsize=(3, 2), constrained_layout=True)
ax.set_title('title')
ax.set_ylabel('y label')
ax.set_xlabel('x label')
ax.plot([0,1], [0,1], label='my text here')
ax.legend(loc='center left', bbox_to_anchor=(1.1, 0.5))
fig.savefig('figure03.pdf')