通过Matplotlib是否可以在一个框中显示文本，并自动换行？使用
pyplot.text()，我只能打印超出窗口边界的多行文本，这很烦人。行的大小事先是未知的...有什么好的建议将不胜感激！3个回答
126
这个答案的内容已经合并到mpl主分支中，链接为https://github.com/matplotlib/matplotlib/pull/4342，将会在下一个特性版本中发布。
哇... 这是一个棘手的问题...（它暴露了matplotlib文本渲染中的许多限制...）
我认为这应该是matplotlib内置的东西，但它没有。在邮件列表上有一些关于此的线程，但我找不到自动换行的解决方案。
首先，无法确定在matplotlib绘制文本字符串之前呈现的大小（以像素为单位）。这不是太大的问题，因为我们可以绘制它，获取大小，然后重新绘制换行的文本。（这很昂贵，但不会太过分）
下一个问题是字符在像素中没有固定的宽度，因此将文本字符串包装到给定数量的字符不一定反映呈现时的给定宽度。不过，这不是一个很大的问题。
除此之外，我们不能只做一次...否则，第一次绘制时（例如在屏幕上），它将被正确地包装，但如果再次绘制（当图形的大小调整或保存为与屏幕不同的DPI图像时），它就不会。这不是一个很大的问题，因为我们可以将回调函数连接到matplotlib绘制事件。
总之，这个解决方案并不完美，但在大多数情况下应该可以工作。我没有尝试考虑tex渲染的字符串，任何拉伸的字体或具有不寻常长宽比的字体。但是，现在它应该正确处理旋转的文本。
然而，在任何您连接到"on_draw"回调的图形中，它都应自动尝试包装多个子图中的任何文本对象... 在许多情况下，它并不完美，但它做得还不错。import matplotlib.pyplot as plt
def main():
fig = plt.figure()
plt.axis([0, 10, 0, 10])
t = "This is a really long string that I'd rather have wrapped so that it"\
" doesn't go outside of the figure, but if it's long enough it will go"\
" off the top or bottom!"
plt.text(4, 1, t, ha='left', rotation=15)
plt.text(5, 3.5, t, ha='right', rotation=-15)
plt.text(5, 10, t, fontsize=18, ha='center', va='top')
plt.text(3, 0, t, family='serif', style='italic', ha='right')
plt.title("This is a really long title that I want to have wrapped so it"\
" does not go outside the figure boundaries", ha='center')
# Now make the text auto-wrap...
fig.canvas.mpl_connect('draw_event', on_draw)
plt.show()
def on_draw(event):
"""Auto-wraps all text objects in a figure at draw-time"""
import matplotlib as mpl
fig = event.canvas.figure
# Cycle through all artists in all the axes in the figure
for ax in fig.axes:
for artist in ax.get_children():
# If it's a text artist, wrap it...
if isinstance(artist, mpl.text.Text):
autowrap_text(artist, event.renderer)
# Temporarily disconnect any callbacks to the draw event...
# (To avoid recursion)
func_handles = fig.canvas.callbacks.callbacks[event.name]
fig.canvas.callbacks.callbacks[event.name] = {}
# Re-draw the figure..
fig.canvas.draw()
# Reset the draw event callbacks
fig.canvas.callbacks.callbacks[event.name] = func_handles
def autowrap_text(textobj, renderer):
"""Wraps the given matplotlib text object so that it exceed the boundaries
of the axis it is plotted in."""
import textwrap
# Get the starting position of the text in pixels...
x0, y0 = textobj.get_transform().transform(textobj.get_position())
# Get the extents of the current axis in pixels...
clip = textobj.get_axes().get_window_extent()
# Set the text to rotate about the left edge (doesn't make sense otherwise)
textobj.set_rotation_mode('anchor')
# Get the amount of space in the direction of rotation to the left and
# right of x0, y0 (left and right are relative to the rotation, as well)
rotation = textobj.get_rotation()
right_space = min_dist_inside((x0, y0), rotation, clip)
left_space = min_dist_inside((x0, y0), rotation - 180, clip)
# Use either the left or right distance depending on the horiz alignment.
alignment = textobj.get_horizontalalignment()
if alignment is 'left':
new_width = right_space
elif alignment is 'right':
new_width = left_space
else:
new_width = 2 * min(left_space, right_space)
# Estimate the width of the new size in characters...
aspect_ratio = 0.5 # This varies with the font!!
fontsize = textobj.get_size()
pixels_per_char = aspect_ratio * renderer.points_to_pixels(fontsize)
# If wrap_width is < 1, just make it 1 character
wrap_width = max(1, new_width // pixels_per_char)
try:
wrapped_text = textwrap.fill(textobj.get_text(), wrap_width)
except TypeError:
# This appears to be a single word
wrapped_text = textobj.get_text()
textobj.set_text(wrapped_text)
def min_dist_inside(point, rotation, box):
"""Gets the space in a given direction from "point" to the boundaries of
"box" (where box is an object with x0, y0, x1, & y1 attributes, point is a
tuple of x,y, and rotation is the angle in degrees)"""
from math import sin, cos, radians
x0, y0 = point
rotation = radians(rotation)
distances = []
threshold = 0.0001
if cos(rotation) > threshold:
# Intersects the right axis
distances.append((box.x1 - x0) / cos(rotation))
if cos(rotation) < -threshold:
# Intersects the left axis
distances.append((box.x0 - x0) / cos(rotation))
if sin(rotation) > threshold:
# Intersects the top axis
distances.append((box.y1 - y0) / sin(rotation))
if sin(rotation) < -threshold:
# Intersects the bottom axis
distances.append((box.y0 - y0) / sin(rotation))
return min(distances)
if __name__ == '__main__':
main()
- Joe Kington
11
9
大约已经过去五年了，但仍然没有一种很好的方法来做到这一点。以下是我所采用的解决方案。我的目标是允许针对个别文本实例选择性地应用像素完美的换行。我还创建了一个简单的textBox()函数，它将转换任何坐标轴为具有自定义边距和对齐方式的文本框。
与其假设特定字体的纵横比或平均宽度，我实际上是逐个单词绘制字符串，并在达到阈值时插入换行符。与近似解相比，这非常缓慢，但对于少于200个单词的字符串仍感觉非常迅速。
与其假设特定字体的纵横比或平均宽度，我实际上是逐个单词绘制字符串，并在达到阈值时插入换行符。与近似解相比，这非常缓慢，但对于少于200个单词的字符串仍感觉非常迅速。
# Text Wrapping
# Defines wrapText which will attach an event to a given mpl.text object,
# wrapping it within the parent axes object. Also defines a the convenience
# function textBox() which effectively converts an axes to a text box.
def wrapText(text, margin=4):
""" Attaches an on-draw event to a given mpl.text object which will
automatically wrap its string wthin the parent axes object.
The margin argument controls the gap between the text and axes frame
in points.
"""
ax = text.get_axes()
margin = margin / 72 * ax.figure.get_dpi()
def _wrap(event):
"""Wraps text within its parent axes."""
def _width(s):
"""Gets the length of a string in pixels."""
text.set_text(s)
return text.get_window_extent().width
# Find available space
clip = ax.get_window_extent()
x0, y0 = text.get_transform().transform(text.get_position())
if text.get_horizontalalignment() == 'left':
width = clip.x1 - x0 - margin
elif text.get_horizontalalignment() == 'right':
width = x0 - clip.x0 - margin
else:
width = (min(clip.x1 - x0, x0 - clip.x0) - margin) * 2
# Wrap the text string
words = [''] + _splitText(text.get_text())[::-1]
wrapped = []
line = words.pop()
while words:
line = line if line else words.pop()
lastLine = line
while _width(line) <= width:
if words:
lastLine = line
line += words.pop()
# Add in any whitespace since it will not affect redraw width
while words and (words[-1].strip() == ''):
line += words.pop()
else:
lastLine = line
break
wrapped.append(lastLine)
line = line[len(lastLine):]
if not words and line:
wrapped.append(line)
text.set_text('\n'.join(wrapped))
# Draw wrapped string after disabling events to prevent recursion
handles = ax.figure.canvas.callbacks.callbacks[event.name]
ax.figure.canvas.callbacks.callbacks[event.name] = {}
ax.figure.canvas.draw()
ax.figure.canvas.callbacks.callbacks[event.name] = handles
ax.figure.canvas.mpl_connect('draw_event', _wrap)
def _splitText(text):
""" Splits a string into its underlying chucks for wordwrapping. This
mostly relies on the textwrap library but has some additional logic to
avoid splitting latex/mathtext segments.
"""
import textwrap
import re
math_re = re.compile(r'(?<!\\)\$')
textWrapper = textwrap.TextWrapper()
if len(math_re.findall(text)) <= 1:
return textWrapper._split(text)
else:
chunks = []
for n, segment in enumerate(math_re.split(text)):
if segment and (n % 2):
# Mathtext
chunks.append('${}$'.format(segment))
else:
chunks += textWrapper._split(segment)
return chunks
def textBox(text, axes, ha='left', fontsize=12, margin=None, frame=True, **kwargs):
""" Converts an axes to a text box by removing its ticks and creating a
wrapped annotation.
"""
if margin is None:
margin = 6 if frame else 0
axes.set_xticks([])
axes.set_yticks([])
axes.set_frame_on(frame)
an = axes.annotate(text, fontsize=fontsize, xy=({'left':0, 'right':1, 'center':0.5}[ha], 1), ha=ha, va='top',
xytext=(margin, -margin), xycoords='axes fraction', textcoords='offset points', **kwargs)
wrapText(an, margin=margin)
return an
使用方法：
ax = plot.plt.figure(figsize=(6, 6)).add_subplot(111)
an = ax.annotate(t, fontsize=12, xy=(0.5, 1), ha='center', va='top', xytext=(0, -6),
xycoords='axes fraction', textcoords='offset points')
wrapText(an)
我删除了一些对我不太重要的功能。调整大小将失败，因为每次调用_wrap()都会向字符串中插入额外的换行符，但无法删除它们。可以通过在_wrap函数中剥离所有\n字符或在包装之间存储原始字符串并在其间“重置”文本实例来解决此问题。
- user65
9
在创建文本框时设置wrap = True，就像下面的例子一样。这可能会达到预期的效果。
plt.text(5, 5, t, ha='right', rotation=-15, wrap=True)
- Daniel.Bourne
4
请点击此处获取更多信息：https://matplotlib.org/gallery/text_labels_and_annotations/autowrap.html - Daniel.Bourne
这是一个良好的近似解决方案（文本超出边界框但并不太多）。 - Eric O. Lebigot
3请注意，这个解决方案（
wrap=True）本质上与被接受的答案相同，因为当使用wrap时，这个答案就是在后台发生的事情。 - ImportanceOfBeingErnest2文本超出边界框对我来说是个致命问题。我想知道为什么他们会包含这样一个有缺陷的实现？ - Joe Coder
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原文链接
原文链接
autowrap_text函数的末尾添加一个调试print wrapped_text，看看实际字符串是否缺少空格...无论如何，我添加了一个更新版本，它（大多数）处理旋转文本。它仍然有很多限制（和许多垂直对齐问题），但希望它还是有用的。 - Joe Kingtonplt.savefig('test.png')替换plt.show()时，为什么它不起作用？ - Claus