plot a line with an arrow

Community matplotlib-users
1

Hi all,

I’m a newbie, I’m trying to plot a line with an arrow
(arrow in the middle and another with an arrow at
the end) with the following points: [1, 2] and [5, 2]
Could anyone please help me with the code?
Thanks.
Harriet A. Welbeck

2

Check the gallery where a few example shows you how to draw arrows.

My recommendation is to use "annotate" with empty string.

e.g.,

annotate("", (1,2), xytext=(5,2), arrowprops=dict(fc="b"))

http://matplotlib.sourceforge.net/api/pyplot_api.html?highlight=annotate#matplotlib.pyplot.annotate

However, a line with an arrow in the middle is not supported. But
something like below may be close enough?

annotate("", (3,5), xytext=(5,5),
         arrowprops=dict(arrowstyle="->", fc="b", shrinkB=0))
annotate("", (1,5), xytext=(3,5),
         arrowprops=dict(arrowstyle="-", fc="b", shrinkA=0))

-JJ

···

On Tue, Jul 14, 2009 at 2:13 PM, Afi Welbeck<welby555@...9...> wrote:

Hi all,

I'm a newbie, I'm trying to plot a line with an arrow
(arrow in the middle and another with an arrow at
the end) with the following points: [1, 2] and [5, 2]
Could anyone please help me with the code?
Thanks.
Harriet A. Welbeck

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3

Hello,

I am trying to add some annotations onto an axis as shown in the attached picture.
Is that do-able? If yes, any pointers on how to achieve this are welcome.

Thanks,

Christophe

AxisAnnotation.jpg

4

Drawing box around a text is quite easy.

http://matplotlib.sourceforge.net/examples/pylab_examples/fancytextbox_demo.html

To place a text in a way like ticklabels, you need to use blended transform.

The short example may give you some starting point.

-JJ

from matplotlib.transforms import blended_transform_factory

ax = subplot(111)
# x position in axes coordinate : 1.02
# y position in data coordinate : 0.3
t = ax.text(1.02, 0.3, "label", ha="left",
            transform=blended_transform_factory(ax.transAxes,
                                                ax.transData),
            bbox=dict(boxstyle="round", fc="cyan"),
            )

···

On Fri, Jul 17, 2009 at 12:51 PM, Christophe Dupre<christophe.dupre@...2631...> wrote:

Hello,

I am trying to add some annotations onto an axis as shown in the attached picture.
Is that do-able? If yes, any pointers on how to achieve this are welcome.

Thanks,

Christophe

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