Legend labels and placement ignored?

Hi -- I'm having a problem with the legend on one of two subplots.
For each curve plotted on each subplot, I set label="something",
and then I set subplot.legend(position). This works for ax2, but
for ax1 it's ignored.

I asked on #matplotlib on Freenode and was advised it looked like
a bug and that I should report it. So I did,
https://github.com/matplotlib/matplotlib/issues/10576
but I thought I'd ask here too, to see if I'm doing something wrong
in the way I specify my legends.

I pared the example program down to this:

···

=======
import matplotlib.pyplot as plt
from matplotlib import gridspec
import numpy as np

def plot_planet():
    tde = np.array([-23.029638, -22.953653, -22.871279, -22.782548, -22.687498, -22.586167, -22.478597, -22.364832, -22.244918, -22.118904, -21.986842])

    obliq_ra = [-3.67878, -3.97686, -4.27044, -4.55928, -4.84302, -5.12142, -5.39412, -5.66088, -5.92146, -6.17544, -6.42264]
    eccen_ra = [ 0.40722, 0.27366, 0.14028, 0.0072, -0.12558, -0.25788, -0.3897, -0.52098, -0.6516, -0.78162, -0.91086]
    true_ra = [-3.27156, -3.7032, -4.13016, -4.55208, -4.9686, -5.3793, -5.78382, -6.18186, -6.57306, -6.95706, -7.3335 ]

    fig = plt.figure(figsize=(12, 8)) # width, height in inches

    gs = gridspec.GridSpec(1, 2, width_ratios=[2.5, 1])

    # Plot equations of time:
    ax1 = fig.add_subplot(gs[0])
    ax1.plot(obliq_ra, label="obliquity", color="lightblue")
    ax1.plot(eccen_ra, label="eccentricity", color="pink")
    ax1.plot(true_ra, label="Eqn of Time", color="black")
    ax1.set_title("Equation of Time")
    ax1.legend("upper left")

    # Plot the analemma:
    ax2 = fig.add_subplot(gs[-1])
    ax2.plot(obliq_ra, tde, label="obliquity", color="lightblue")
    ax2.plot(eccen_ra, tde, label="eccentricity", color="pink")
    ax2.plot(true_ra, tde, label="analemma", color="black")
    ax2.set_title("Analemma")
    ax2.legend(loc="upper right")

    plt.show()

if __name__ == '__main__':
    plot_planet()

Here's what I see: http://shallowsky.com/tmp/mpl-legend.jpg
Note that the left subplot (ax1) has the legend in the upper right
even though I specified upper left, and that the labels are
mysteriously u, p, and p -- I can't figure out where those labels
are coming from but they're clearly not the ones I specified.

Any idea how I could fix this? Thanks!

        ...Akkana

Hi Akkana,

Just to be sure, did you try with

ax1.legend(loc="upper left")  # instead of ax1.legend("upper left")

Best,
Adrien

···

On 02/23/2018 01:01 PM, Akkana Peck wrote:

Hi -- I'm having a problem with the legend on one of two subplots.
For each curve plotted on each subplot, I set label="something",
and then I set subplot.legend(position). This works for ax2, but
for ax1 it's ignored.

I asked on #matplotlib on Freenode and was advised it looked like
a bug and that I should report it. So I did,
https://github.com/matplotlib/matplotlib/issues/10576
but I thought I'd ask here too, to see if I'm doing something wrong
in the way I specify my legends.

I pared the example program down to this:

=======
import matplotlib.pyplot as plt
from matplotlib import gridspec
import numpy as np

def plot_planet():
     tde = np.array([-23.029638, -22.953653, -22.871279, -22.782548, -22.687498, -22.586167, -22.478597, -22.364832, -22.244918, -22.118904, -21.986842])

     obliq_ra = [-3.67878, -3.97686, -4.27044, -4.55928, -4.84302, -5.12142, -5.39412, -5.66088, -5.92146, -6.17544, -6.42264]
     eccen_ra = [ 0.40722, 0.27366, 0.14028, 0.0072, -0.12558, -0.25788, -0.3897, -0.52098, -0.6516, -0.78162, -0.91086]
     true_ra = [-3.27156, -3.7032, -4.13016, -4.55208, -4.9686, -5.3793, -5.78382, -6.18186, -6.57306, -6.95706, -7.3335 ]

     fig = plt.figure(figsize=(12, 8)) # width, height in inches

     gs = gridspec.GridSpec(1, 2, width_ratios=[2.5, 1])

     # Plot equations of time:
     ax1 = fig.add_subplot(gs[0])
     ax1.plot(obliq_ra, label="obliquity", color="lightblue")
     ax1.plot(eccen_ra, label="eccentricity", color="pink")
     ax1.plot(true_ra, label="Eqn of Time", color="black")
     ax1.set_title("Equation of Time")
     ax1.legend("upper left")

     # Plot the analemma:
     ax2 = fig.add_subplot(gs[-1])
     ax2.plot(obliq_ra, tde, label="obliquity", color="lightblue")
     ax2.plot(eccen_ra, tde, label="eccentricity", color="pink")
     ax2.plot(true_ra, tde, label="analemma", color="black")
     ax2.set_title("Analemma")
     ax2.legend(loc="upper right")

     plt.show()

if __name__ == '__main__':
     plot_planet()

Here's what I see: http://shallowsky.com/tmp/mpl-legend.jpg
Note that the left subplot (ax1) has the legend in the upper right
even though I specified upper left, and that the labels are
mysteriously u, p, and p -- I can't figure out where those labels
are coming from but they're clearly not the ones I specified.

Any idea how I could fix this? Thanks!

         ...Akkana
_______________________________________________
Matplotlib-users mailing list
Matplotlib-users at python.org
https://mail.python.org/mailman/listinfo/matplotlib-users

That's it! Adding loc= fixes the problem. Many thanks!

So I guess the u, p and p were coming from iterating over the string
"upper left". How funny! (Funny now that it's solved, anyway. :slight_smile:

        ...Akkana

vincent.adrien at gmail.com writes:

···

Hi Akkana,

Just to be sure, did you try with

ax1.legend(loc="upper left")  # instead of ax1.legend("upper left")

Best,
Adrien

On 02/23/2018 01:01 PM, Akkana Peck wrote:
> Hi -- I'm having a problem with the legend on one of two subplots.
> For each curve plotted on each subplot, I set label="something",
> and then I set subplot.legend(position). This works for ax2, but
> for ax1 it's ignored.
>
> I asked on #matplotlib on Freenode and was advised it looked like
> a bug and that I should report it. So I did,
> https://github.com/matplotlib/matplotlib/issues/10576
> but I thought I'd ask here too, to see if I'm doing something wrong
> in the way I specify my legends.
>
> I pared the example program down to this:
>
> =======
> import matplotlib.pyplot as plt
> from matplotlib import gridspec
> import numpy as np
>
> def plot_planet():
> tde = np.array([-23.029638, -22.953653, -22.871279, -22.782548, -22.687498, -22.586167, -22.478597, -22.364832, -22.244918, -22.118904, -21.986842])
>
> obliq_ra = [-3.67878, -3.97686, -4.27044, -4.55928, -4.84302, -5.12142, -5.39412, -5.66088, -5.92146, -6.17544, -6.42264]
> eccen_ra = [ 0.40722, 0.27366, 0.14028, 0.0072, -0.12558, -0.25788, -0.3897, -0.52098, -0.6516, -0.78162, -0.91086]
> true_ra = [-3.27156, -3.7032, -4.13016, -4.55208, -4.9686, -5.3793, -5.78382, -6.18186, -6.57306, -6.95706, -7.3335 ]
>
> fig = plt.figure(figsize=(12, 8)) # width, height in inches
>
> gs = gridspec.GridSpec(1, 2, width_ratios=[2.5, 1])
>
> # Plot equations of time:
> ax1 = fig.add_subplot(gs[0])
> ax1.plot(obliq_ra, label="obliquity", color="lightblue")
> ax1.plot(eccen_ra, label="eccentricity", color="pink")
> ax1.plot(true_ra, label="Eqn of Time", color="black")
> ax1.set_title("Equation of Time")
> ax1.legend("upper left")
>
> # Plot the analemma:
> ax2 = fig.add_subplot(gs[-1])
> ax2.plot(obliq_ra, tde, label="obliquity", color="lightblue")
> ax2.plot(eccen_ra, tde, label="eccentricity", color="pink")
> ax2.plot(true_ra, tde, label="analemma", color="black")
> ax2.set_title("Analemma")
> ax2.legend(loc="upper right")
>
> plt.show()
>
> if __name__ == '__main__':
> plot_planet()
> =======
>
> Here's what I see: http://shallowsky.com/tmp/mpl-legend.jpg
> Note that the left subplot (ax1) has the legend in the upper right
> even though I specified upper left, and that the labels are
> mysteriously u, p, and p -- I can't figure out where those labels
> are coming from but they're clearly not the ones I specified.
>
> Any idea how I could fix this? Thanks!
>
> ...Akkana
> _______________________________________________
> Matplotlib-users mailing list
> Matplotlib-users at python.org
> https://mail.python.org/mailman/listinfo/matplotlib-users
>

_______________________________________________
Matplotlib-users mailing list
Matplotlib-users at python.org
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Yes, my guess is that it was using the signature `legend(labels,
*kwargs)`, where `loc` is expected as a *keyword* (not a positional)
argument. Thus the string was taken as the list of the desired labels
and `loc` was defaulting to "best".

Best,
Adrien

···

On 02/23/2018 01:57 PM, Akkana Peck wrote:

That's it! Adding loc= fixes the problem. Many thanks!

So I guess the u, p and p were coming from iterating over the string
"upper left". How funny! (Funny now that it's solved, anyway. :slight_smile:

         ...Akkana

vincent.adrien at gmail.com writes:

Hi Akkana,

Just to be sure, did you try with

ax1.legend(loc="upper left")  # instead of ax1.legend("upper left")

Best,
Adrien

On 02/23/2018 01:01 PM, Akkana Peck wrote:

Hi -- I'm having a problem with the legend on one of two subplots.
For each curve plotted on each subplot, I set label="something",
and then I set subplot.legend(position). This works for ax2, but
for ax1 it's ignored.

I asked on #matplotlib on Freenode and was advised it looked like
a bug and that I should report it. So I did,
https://github.com/matplotlib/matplotlib/issues/10576
but I thought I'd ask here too, to see if I'm doing something wrong
in the way I specify my legends.

I pared the example program down to this:

=======
import matplotlib.pyplot as plt
from matplotlib import gridspec
import numpy as np

def plot_planet():
      tde = np.array([-23.029638, -22.953653, -22.871279, -22.782548, -22.687498, -22.586167, -22.478597, -22.364832, -22.244918, -22.118904, -21.986842])

      obliq_ra = [-3.67878, -3.97686, -4.27044, -4.55928, -4.84302, -5.12142, -5.39412, -5.66088, -5.92146, -6.17544, -6.42264]
      eccen_ra = [ 0.40722, 0.27366, 0.14028, 0.0072, -0.12558, -0.25788, -0.3897, -0.52098, -0.6516, -0.78162, -0.91086]
      true_ra = [-3.27156, -3.7032, -4.13016, -4.55208, -4.9686, -5.3793, -5.78382, -6.18186, -6.57306, -6.95706, -7.3335 ]

      fig = plt.figure(figsize=(12, 8)) # width, height in inches

      gs = gridspec.GridSpec(1, 2, width_ratios=[2.5, 1])

      # Plot equations of time:
      ax1 = fig.add_subplot(gs[0])
      ax1.plot(obliq_ra, label="obliquity", color="lightblue")
      ax1.plot(eccen_ra, label="eccentricity", color="pink")
      ax1.plot(true_ra, label="Eqn of Time", color="black")
      ax1.set_title("Equation of Time")
      ax1.legend("upper left")

      # Plot the analemma:
      ax2 = fig.add_subplot(gs[-1])
      ax2.plot(obliq_ra, tde, label="obliquity", color="lightblue")
      ax2.plot(eccen_ra, tde, label="eccentricity", color="pink")
      ax2.plot(true_ra, tde, label="analemma", color="black")
      ax2.set_title("Analemma")
      ax2.legend(loc="upper right")

      plt.show()

if __name__ == '__main__':
      plot_planet()

Here's what I see: http://shallowsky.com/tmp/mpl-legend.jpg
Note that the left subplot (ax1) has the legend in the upper right
even though I specified upper left, and that the labels are
mysteriously u, p, and p -- I can't figure out where those labels
are coming from but they're clearly not the ones I specified.

Any idea how I could fix this? Thanks!

          ...Akkana
_______________________________________________
Matplotlib-users mailing list
Matplotlib-users at python.org
https://mail.python.org/mailman/listinfo/matplotlib-users

_______________________________________________
Matplotlib-users mailing list
Matplotlib-users at python.org
https://mail.python.org/mailman/listinfo/matplotlib-users

_______________________________________________
Matplotlib-users mailing list
Matplotlib-users at python.org
https://mail.python.org/mailman/listinfo/matplotlib-users