CODEWITHSUNDEEP
pythonmatplotlib
Pakox.Wang
Pakox.Wang

Reputation: 61

Matplotlib - Setting up rcParams for moving xlabel to the top?

I need all of my figures to have xlabel, xticks and xticklabels on the top. Since of that, I wrote a function to adjust plt.rcParams which serves for initializing purpose.

However, it seems there is no such parameter to setup xlabel to the top in advance. Here is a simplified showcase:

import numpy as np
import matplotlib.pyplot as plt

plt.rcParams['xtick.bottom'] = False
plt.rcParams['xtick.labelbottom'] = False
plt.rcParams['xtick.top'] = True
plt.rcParams['xtick.labeltop'] = True

data = np.arange(9).reshape((3,3))

f,ax = plt.subplots()
ax.imshow(data)
ax.set_xlabel('x label')
ax.set_ylabel('y label')

Output: enter image description here

Currently the way I found to adjust it is putting ax.xaxis.set_label_position('top') after calling ax.set_xlabel('x label').

I'm looking for a solution with two goals:

  1. It change the default x-label position so that every time ax.set_xlabel() is called, it shows up at the top.
  2. This step could be executed before calling ax.set_xlabel()

So I don't have to use ax.xaxis.set_label_position() individually every time.

Extra: As @r-beginners mentioned, the official reference did provide a example. But in the script they called is ax.set_title('xlabel top'), which is different from ax.set_xlabel('x label'). Note that a title is always on the top by default, regardless setting up plt.rcParams or not. I assume they missed this issue by mistake.

Upvotes: 1

Views: 2226

Answers (2)

gboffi
gboffi

Reputation: 25033

As far as I can tell, the position of the label of the x axis is hard-coded.

Let's look at the definition of the XAxis class, the relevant file is .../matplotlib/axis.py

class XAxis(Axis):
    ...
    def _get_label(self):
        # x in axes coords, y in display coords (to be updated at draw
        # time by _update_label_positions)
        label = mtext.Text(x=0.5, y=0,
                           fontproperties=font_manager.FontProperties(
                               size=rcParams['axes.labelsize'],
                               weight=rcParams['axes.labelweight']),
                           color=rcParams['axes.labelcolor'],
                           verticalalignment='top',
                           horizontalalignment='center')

        label.set_transform(mtransforms.blended_transform_factory(
            self.axes.transAxes, mtransforms.IdentityTransform()))

        self._set_artist_props(label)
        self.label_position = 'bottom'
        return label
    ...

As you can see, the vertical position of the label is hard-coded in the call to Text, y=0 in display coordinates, to be updated at display time by _update_label_positions and the label_position is hard-coded to 'bottom'.

Upvotes: 1

r-beginners
r-beginners

Reputation: 35155

There is an explanation in the official reference. This will help you deal with it.

import matplotlib.pyplot as plt
import numpy as np

# plt.rcParams['xtick.bottom'] = plt.rcParams['xtick.labelbottom'] = False
# plt.rcParams['xtick.top'] = plt.rcParams['xtick.labeltop'] = True

x = np.arange(10)

fig, ax = plt.subplots()

ax.plot(x)
ax.set_xlabel('xlabel top')  # Note title moves to make room for ticks

secax = ax.secondary_xaxis('top')
secax.set_xlabel('new label top')

plt.show()

enter image description here

Upvotes: 0

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