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Matplotlib incorrect display of data on the y-axis. Bars are displayed from coordinate 0.5 to 1.0, but this is not what I would like to see. Coordinates 1.0 are not in the data (height and bottom)
Code for example:
fig, ax = plt.subplots()
x = [0, 1, 2, 3, 4]
height = [0.5047, 0.4999, 0.4985, 0.4999, 0.4987]
bottom = [0.5002, 0.4969, 0.4956, 0.4969, 0.4967]
ax.set_ylim(0, 2)
ax.bar(x=x, height=height, width=0.2, bottom=bottom)
plt.show()
see the output here
Matplotlib Pyplot Bars use the
bottom parameter to define the y-coordinate of the bottom of the bar
height parameter to define the hight of the bar
Consequently, your bars start at bottom and end at bottom+height.
If you calculate the sum of each of coordinates, you will see that they all end roughly at about 1.0:
print([sum(x) for x in zip(height, bottom)]) results in
[1.0049000000000001, 0.9968, 0.9941, 0.9968]
If you aim at drawing bars, whose y-coordinate start at bottom and end at height, then subtract them first
fig, ax = plt.subplots()
x = [0, 1, 2, 3, 4]
height = [0.5047, 0.4999, 0.4985, 0.4999, 0.4987]
bottom = [0.5002, 0.4969, 0.4956, 0.4969, 0.4967]
tmpHeight = tuple(map(lambda i, j: i - j, height, bottom))
ax.bar(x=x, height=tmpHeight , width=0.2, bottom=bottom)
plt.show()
I want to completely remove white space around my axes during active plot (not save_fig as others asked).
Here we cannot use bbox_inches='tight'. I can use tight_layout(pad=0).
When axis is on, it works fine, it shows all the ticks and x-y labels.
However, in some cases, I set the axis off. What I expected is to see the contents expand to fill up the empty space where the axes are. However, this does not work. It still keep the padding as there are still x-y labels and axes.
How can I remove the white space of invisible axes objects?
edit:
I am aware that I can use ax.set_yticks([]) and ax.set_xticks([]) to turn those off. But this is clumsy, I have to remember the the ticks before I clear them. And if I remove-then-add those ticks. The ticks cannot automatically update any more.
I wonder is there any more straightforward way to do this?
We can still see there is a small border spacing even after removing all ticks. If someone can come up a way to remove that too. It will be fantastic.
I would also like to keep the title if there is one. Thus the hard-coded ax.set_position([0,0,1,x]) is not very good for this usage. Surely we can still try to get the top spacing when there is a title, but if someone can provide a more direct/simple way to handle this, it will be preferred.
Example code:
def demo_tight_layout(w=10, h=6, axisoff=False, removeticks=False):
fig,ax = plt.subplots()
fig.set_facecolor((0.8, 0.8, 0.8))
rect = patches.Rectangle((-w/2, -h/2), w, h, color='#00ffff', alpha=0.5)
ax.add_patch(rect)
ax.plot([-w/2,w/2], [-h/2,h/2])
ax.plot([-w/2,w/2], [h/2,-h/2])
ax.set_ylabel("ylabel")
ax.margins(0)
_texts = []
if axisoff:
ax.set_axis_off()
_texts.append("axisoff")
if removeticks:
ax.set_xticks([])
ax.set_yticks([])
ax.set_ylabel("")
_texts.append("removeticks")
fig.text(0.5, 0.6, " ".join(_texts))
fig.tight_layout(pad=0)
plt.show()
return fig, ax, text
You may adjust the subplot parameters depending on whether you turned the axis off or not.
import matplotlib.pyplot as plt
from matplotlib import patches
def demo_tight_layout(w=10, h=6, axisoff=False):
fig,ax = plt.subplots()
fig.set_facecolor((0.8, 0.8, 0.8))
rect = patches.Rectangle((-w/2, -h/2), w, h, color='#00ffff', alpha=0.5)
ax.add_patch(rect)
ax.plot([-w/2,w/2], [-h/2,h/2])
ax.plot([-w/2,w/2], [h/2,-h/2])
ax.set_ylabel("ylabel")
ax.margins(0)
_texts = []
fig.tight_layout()
if axisoff:
ax.set_axis_off()
_texts.append("axisoff")
params = dict(bottom=0, left=0, right=1)
if ax.get_title() == "":
params.update(top=1)
fig.subplots_adjust(**params)
fig.text(0.5, 0.6, " ".join(_texts))
plt.show()
Now demo_tight_layout(axisoff=True) produces
and demo_tight_layout(axisoff=False) produces
You need to set the axes position to fill the figure. If you create your figure and plot with
import matplotlib.pyplot as plt
fig = plt.figure()
ax = fig.gca()
ax.plot(some_x_data, some_y_data)
you need to add the following line to fill the figure with the axes:
ax.set_position([0, 0, 1, 1], which='both')
This sets the axes location relative to the figure size in the following way:
[left, bottom, width, height]
So to completely fill the figure use [0, 0, 1, 1] as shown above.
So taking your code, it should look like this (using fill_figure bool to check):
def demo_tight_layout(w=10, h=6, axisoff=False, removeticks=False, fill_figure=False):
fig,ax = plt.subplots()
fig.set_facecolor((0.8, 0.8, 0.8))
rect = patches.Rectangle((-w/2, -h/2), w, h, color='#00ffff', alpha=0.5)
ax.add_patch(rect)
ax.plot([-w/2,w/2], [-h/2,h/2])
ax.plot([-w/2,w/2], [h/2,-h/2])
ax.set_ylabel("ylabel")
ax.margins(0)
_texts = []
if axisoff:
ax.set_axis_off()
_texts.append("axisoff")
if removeticks:
ax.set_xticks([])
ax.set_yticks([])
ax.set_ylabel("")
_texts.append("removeticks")
fig.text(0.5, 0.6, " ".join(_texts))
fig.tight_layout(pad=0)
if fill_figure:
ax.set_position([0, 0, 1, 1], which='both')
plt.show()
return fig, ax, text
ax.set_position needs to be after fig.tight_layout.
If a figure title is needed, there is no direct way to do it. This unluckily can't be avoided. You need to adapt the height parameters manually so that the title fits in the figure, for example with:
ax.set_position([0, 0, 1, .9], which='both')
I'm trying to make a plot with one panel up top (colspan = 2) and two plots below, with a controlled amount of space between them. I'd like the bounds of the plots to be in alignment. Here's what I'm starting with:
import cartopy
from matplotlib import pyplot
from matplotlib.gridspec import GridSpec
gs = GridSpec(2, 2, height_ratios=[2, 1], hspace=0, wspace=0)
ax0 = pyplot.subplot(gs[0, :], projection=cartopy.crs.LambertConformal())
ax0.add_feature(cartopy.feature.COASTLINE)
ax0.set_extent([-120, -75, 20, 52], cartopy.crs.Geodetic())
ax1 = pyplot.subplot(gs[1, 0], projection=cartopy.crs.LambertConformal())
ax1.add_feature(cartopy.feature.COASTLINE)
ax1.set_extent([-90, -75, 20, 30], cartopy.crs.Geodetic())
ax2 = pyplot.subplot(gs[1, 1], projection=cartopy.crs.LambertConformal())
ax2.add_feature(cartopy.feature.COASTLINE)
ax2.set_extent([-90, -75, 20, 30], cartopy.crs.Geodetic())
pyplot.show()
First problem is that the wspace=0 parameter doesn't take.
Second problem is (at least this is my guess on how to proceed) calculating a height ratio that will make the width of the upper subplot equal the combined width of the lower subplots (plus any wspace).
I have something like
import matplotlib.pyplot as plt
import numpy as np
a=[0.05, 0.1, 0.2, 1, 2, 3]
plt.hist((a*2, a*3), bins=[0, 0.1, 1, 10])
plt.gca().set_xscale("symlog", linthreshx=0.1)
plt.show()
which gives me the following plot:
As one can see, the bar width is not equal. In the linear part (from 0 to 0.1), everything is find, but after this, the bar width is still in linear scale, while the axis is in logarithmic scale, giving me uneven widths for bars and spaces in between (the tick is not in the middle of the bars).
Is there any way to correct this?
Inspired by https://stackoverflow.com/a/30555229/635387 I came up with the following solution:
import matplotlib.pyplot as plt
import numpy as np
d=[0.05, 0.1, 0.2, 1, 2, 3]
def LogHistPlot(data, bins):
totalWidth=0.8
colors=("b", "r", "g")
for i, d in enumerate(data):
heights = np.histogram(d, bins)[0]
width=1/len(data)*totalWidth
left=np.array(range(len(heights))) + i*width
plt.bar(left, heights, width, color=colors[i], label=i)
plt.xticks(range(len(bins)), bins)
plt.legend(loc='best')
LogHistPlot((d*2, d*3, d*4), [0, 0.1, 1, 10])
plt.show()
Which produces this plot:
The basic idea is to drop the plt.hist function, compute the histogram by numpy and plot it with plt.bar. Than, you can easily use a linear x-axis, which makes the bar width calculation trivial. Lastly, the ticks are replaced by the bin edges, resulting in the logarithmic scale. And you don't even have to deal with the symlog linear/logarithmic botchery anymore.
You could use histtype='stepfilled' if you are okay with a plot where the data sets are plotted one behind the other. Of course, you'll need to carefully choose colors with alpha values, so that all your data can still be seen...
a = [0.05, 0.1, 0.2, 1, 2, 3] * 2
b = [0.05, 0.05, 0.05, 0.15, 0.15, 2]
colors = [(0.2, 0.2, 0.9, 0.5), (0.9, 0.2, 0.2, 0.5)] # RGBA tuples
plt.hist((a, b), bins=[0, 0.1, 1, 10], histtype='stepfilled', color=colors)
plt.gca().set_xscale("symlog", linthreshx=0.1)
plt.show()
I've changed your data slightly for a better illustration. This gives me:
For some reason the overlap color seems to be going wrong (matplotlib 1.3.1 with Python 3.4.0; Is this a bug?), but it's one possible solution/alternative to your problem.
Okay, I found out the real problem: when you create the histogram with those bin-edge settings, the histogram creates bars which have equal size, and equal outside-spacing on the non-log scale.
To demonstrate, here's a zoomed-in version of the plot in the question, but in non-log scale:
Notice how the first two bars are centered around (0 + 0.1) / 2 = 0.05, with a gap of 0.1 / 10 = 0.01 at the edges, while the next two bars are centered around (0.1 + 1.0) / 2 = 0.55, with a gap of 1.1 / 10 = 0.11 at either edge.
When converting things to log scale, bar widths and edge widths all go for a huge toss. This is compounded further by the fact that you have a linear scale from 0 to 0.1, after which things become log-scale.
I know no way of fixing this, other than to do everything manually. I've used the geometric means of the bin-edges in order to compute what the bar edges and bar widths should be. Note that this piece of code will work only for two datasets. If you have more datasets, you'll need to have some function that fills in the bin-edges with a geometric series appropriately.
import numpy as np
import matplotlib.pyplot as plt
def geometric_means(a):
"""Return pairwise geometric means of adjacent elements."""
return np.sqrt(a[1:] * a[:-1])
a = [0.05, 0.1, 0.2, 1, 2, 3] * 2
b = [0.05, 0.1, 0.2, 1, 2, 3] * 3
# Find frequencies
bins = np.array([0, 0.1, 1, 10])
a_hist = np.histogram(a, bins=bins)[0]
b_hist = np.histogram(b, bins=bins)[0]
# Find log-scale mid-points for bar-edges
mid_vals = np.hstack((np.array([0.05,]), geometric_means(bins[1:])))
# Compute bar left-edges, and bar widths
a_x = np.empty(mid_vals.size * 2)
a_x = bins[:-1]
a_widths = mid_vals - bins[:-1]
b_x = np.empty(mid_vals.size * 2)
b_x = mid_vals
b_widths = bins[1:] - mid_vals
plt.bar(a_x, a_hist, width=a_widths, color='b')
plt.bar(b_x, b_hist, width=b_widths, color='g')
plt.gca().set_xscale("symlog", linthreshx=0.1)
plt.show()
And the final result:
Sorry, but the neat gaps between the bars get killed. Again, this can be fixed by doing the appropriate geometric interpolation, so that everything is linear on log-scale.
Just in case someone stumbles upon this problem:
This solution looks much more like the way it should be
plotting a histogram on a Log scale with Matplotlib
The following screenshot shows my x-axis.
I added some labels and rotated them by 90 degrees in order to better read them. However, pyplot truncates the bottom such that I'm not able to completely read the labels.
How do I extend the bottom margin in order to see the complete labels?
Two retroactive ways:
fig, ax = plt.subplots()
# ...
fig.tight_layout()
Or
fig.subplots_adjust(bottom=0.2) # or whatever
Here's a subplots_adjust example: http://matplotlib.org/examples/pylab_examples/subplots_adjust.html
(but I prefer tight_layout)
A quick one-line solution that has worked for me is to use pyplot's auto tight_layout method directly, available in Matplotlib v1.1 onwards:
plt.tight_layout()
This can be invoked immediately before you show the plot (plt.show()), but after your manipulations on the axes (e.g. ticklabel rotations, etc).
This convenience method avoids manipulating individual figures of subplots.
Where plt is the standard pyplot from:
import matplotlib.pyplot as plt
fig.savefig('name.png', bbox_inches='tight')
works best for me, since it doesn't reduce the plot size compared to
fig.tight_layout()
Subplot-adjust did not work for me, since the whole figure would just resize with the labels still out of bounds.
A workaround I found was to keep the y-axis always a certain margin over the highest or minimum y-values:
x1,x2,y1,y2 = plt.axis()
plt.axis((x1,x2,y1 - 100 ,y2 + 100))
fig, ax = plt.subplots(tight_layout=True)
This is rather complicated, but it gives a general and neat solution.
import numpy as np
value1 = 3
xvalues = [0, 1, 2, 3, 4]
line1 = [2.0, 3.0, 2.0, 5.0, 4.0]
stdev1 = [0.1, 0.2, 0.1, 0.4, 0.3]
line2 = [1.7, 3.1, 2.5, 4.8, 4.2]
stdev2 = [0.12, 0.18, 0.12, 0.3, 0.35]
max_times = [max(line1+stdev1),max(line2+stdev2)]
min_times = [min(line1+stdev1),min(line2+stdev2)]
font_size = 25
max_total = max(max_times)
min_total = min(min_times)
max_minus_min = max_total - min_total
step_size = max_minus_min/10
head_space = (step_size*3)
plt.figure(figsize=(15, 15))
plt.errorbar(xvalues, line1, yerr=stdev1, fmt='', color='b')
plt.errorbar(xvalues, line2, yerr=stdev2, fmt='', color='r')
plt.xlabel("xvalues", fontsize=font_size)
plt.ylabel("lines 1 and 2 Test "+str(value1), fontsize=font_size)
plt.title("Let's leave space for the legend Experiment"+ str(value1), fontsize=font_size)
plt.legend(("Line1", "Line2"), loc="upper left", fontsize=font_size)
plt.tick_params(labelsize=font_size)
plt.yticks(np.arange(min_total, max_total+head_space, step=step_size) )
plt.grid()
plt.tight_layout()
Result: