Matplotlib set_data for errorbar plot

Question

Matplotlib\'s line2D objects, such as those returned by a call to plot, have a convenient method, set_data, that let\'s me quickly upd

Answer 1

Thanks to the help from @tacaswell. Below is the python function that can both update xerr and yerr, as well as the x_data and y_data for the baseline plotting:

def adjustErrbarxy(self, errobj, x, y, x_error, y_error):
    ln, (errx_top, errx_bot, erry_top, erry_bot), (barsx, barsy) = errobj
    x_base = x
    y_base = y

    xerr_top = x_base + x_error
    xerr_bot = x_base - x_error
    yerr_top = y_base + y_error
    yerr_bot = y_base - y_error

    errx_top.set_xdata(xerr_top)
    errx_bot.set_xdata(xerr_bot)
    errx_top.set_ydata(y_base)
    errx_bot.set_ydata(y_base)

    erry_top.set_xdata(x_base)
    erry_bot.set_xdata(x_base)
    erry_top.set_ydata(yerr_top)
    erry_bot.set_ydata(yerr_bot)

    new_segments_x = [np.array([[xt, y], [xb,y]]) for xt, xb, y in zip(xerr_top, xerr_bot, y_base)]
    new_segments_y = [np.array([[x, yt], [x,yb]]) for x, yt, yb in zip(x_base, yerr_top, yerr_bot)]
    barsx.set_segments(new_segments_x)
    barsy.set_segments(new_segments_y)

The first input parameter (self is for python class) is the already created errorbar plot handler, that is also the object whose properties need to be updated; x and y are the updated numpy arrays which should be shown the average values along x and y axis; the last two parameters x_error and y_error are the errorbar ranges calculated for x and y arrays. If only the errorbars are need to be updated, the x_base and y_base should be writen as ln.get_xdata() and ln.get_ydata(), respectively.

Up to now, the solution for the errorbar updating in matplotlib is truly non-trivial, hope it be much easier in the future versions.

Answer 2

I followed the link provided by Tong and learned that there is a problem in his code - input of self variable is not needed. There is also a more generalized solution provided by mitpre - I used it and it works great. Below is the code for quicker reference:

def update_errorbar(errobj, x, y, xerr=None, yerr=None):
    ln, caps, bars = errobj


    if len(bars) == 2:
        assert xerr is not None and yerr is not None, "Your errorbar object has 2 dimension of error bars defined. You must provide xerr and yerr."
        barsx, barsy = bars  # bars always exist (?)
        try:  # caps are optional
            errx_top, errx_bot, erry_top, erry_bot = caps
        except ValueError:  # in case there is no caps
            pass

    elif len(bars) == 1:
        assert (xerr is     None and yerr is not None) or\
               (xerr is not None and yerr is     None),  \
               "Your errorbar object has 1 dimension of error bars defined. You must provide xerr or yerr."

        if xerr is not None:
            barsx, = bars  # bars always exist (?)
            try:
                errx_top, errx_bot = caps
            except ValueError:  # in case there is no caps
                pass
        else:
            barsy, = bars  # bars always exist (?)
            try:
                erry_top, erry_bot = caps
            except ValueError:  # in case there is no caps
                pass

    ln.set_data(x,y)

    try:
        errx_top.set_xdata(x + xerr)
        errx_bot.set_xdata(x - xerr)
        errx_top.set_ydata(y)
        errx_bot.set_ydata(y)
    except NameError:
        pass
    try:
        barsx.set_segments([np.array([[xt, y], [xb, y]]) for xt, xb, y in zip(x + xerr, x - xerr, y)])
    except NameError:
        pass

    try:
        erry_top.set_xdata(x)
        erry_bot.set_xdata(x)
        erry_top.set_ydata(y + yerr)
        erry_bot.set_ydata(y - yerr)
    except NameError:
        pass
    try:
        barsy.set_segments([np.array([[x, yt], [x, yb]]) for x, yt, yb in zip(x, y + yerr, y - yerr)])
    except NameError:
        pass