Hi Matt,<br><br>I tried removing take_log from the add_field and get the same error.<br><br>With  take_log = False, it runs happily but always gives me a linear colour bar scale. <br><br>I tried:<br>        q = pc.add_projection("RadiationForceMagnitude", ax, weight_field="Density", figure=fig, axes=axes[0][1], use_colorbar=False)<br>

        q.set_cmap("binary")<br>        q.set_log_field(True)<br>        q.set_zlim(rp_min, rp_max)<br><br>but get:<br>Traceback (most recent call last):<br>  File "MultiRadPressure.py", line 78, in <module><br>

    p._redraw_image()<br>  File "/home/h-clark/YT/src/yt-hg/yt/visualization/plot_types.py", line 384, in _redraw_image<br>    newmin = na.nanmin(buff[bI])<br>  File "/home/h-clark/YT/lib/python2.6/site-packages/numpy/lib/function_base.py", line 1494, in nanmin<br>

    return _nanop(np.min, np.inf, a, axis)<br>  File "/home/h-clark/YT/lib/python2.6/site-packages/numpy/lib/function_base.py", line 1355, in _nanop<br>    res = op(y, axis=axis)<br>  File "/home/h-clark/YT/lib/python2.6/site-packages/numpy/core/fromnumeric.py", line 1829, in amin<br>

    return amin(axis, out)<br>ValueError: zero-size array to ufunc.reduce without identity<br><br>whenever the RadAccel fields are all zero.<br><br>Is there another way?<br><br>Libby<br><br><br>Script:<br>from yt.mods import * # set up our namespace<br>
import matplotlib.colorbar as cb<br>import os<br><br>orient = 'horizontal'<br>frame_template = "aaSN/%s/RPmultiplotproj_%02ipc_%01i_%04i.eps"<br><br>ss = float(sys.argv[2])<br>rho_min = 1.e-25<br>rho_max = 1.e-20<br>
temp_min = 1<br>temp_max = 10000<br>HII_min = 1.e-5<br>HII_max = 1.0<br>rp_min = 1e24<br>rp_max = 5e27<br><br>name = sys.argv[1]<br><br>firststar = 0<br><br>def _ConvertAccel(data):<br>    return data.convert("Length") / (data.convert("Time"))**2.0<br>
def _RadiationAccelerationMagnitude(field, data):<br>    return ( (data["RadAccel1"])**2.0 + \<br>             (data["RadAccel2"])**2.0 + \<br>             (data["RadAccel3"])**2.0 )**(1.0/2.0)<br>
add_field("RadiationAccelerationMagnitude", function=_RadiationAccelerationMagnitude, take_log=False,convert_function=_ConvertAccel, units=r"\rm{cm}/\rm{s}^{2}")<br>def _RadiationForceMagnitude(field, data):<br>
    return ( data["RadiationAccelerationMagnitude"] * data["Density"] * data["CellVolume"])<br>add_field("RadiationForceMagnitude", function=_RadiationForceMagnitude, take_log=False, units=r"\rm{dynes}")<br>
<br><br><br>for n in range(212,400,1):<br>    pf = load("SciNet/%s/DD%04i/data%04i" % (name,n, n)) # load data<br>    #pf = load("WOCOUT/%s/DD%04i/data%04i" % (sys.argv[-1],n, n)) # load data<br>    if pf is None: continue<br>
    if na.any(pf.h.grid_particle_count):<br>        v1, c1 = pf.h.find_max("RadAccel1")<br>        v2, c2 = pf.h.find_max("RadAccel2")<br>        v3, c3 = pf.h.find_max("RadAccel3")<br>        v4, c4 = pf.h.find_max("RadiationForceMagnitude")<br>
    for ax in range (0,1):<br>##         if os.path.exists(frame_template % (name,ss,ax,n)) is True:<br>##              print "file exists"<br>##              continue<br>        xc = 0.5<br>        yc = 0.5<br>
        zc = 0.5   <br>        print "Dump:", n, "axis:", ax<br><br>        fig, axes, colorbars = get_multi_plot( 2, 1, colorbar=orient, bw = 6)<br><br>        pc = PlotCollection(pf, center=(xc, yc, zc))<br>
<br>        p = pc.add_projection("Density", ax,  weight_field="Density", figure = fig, axes = axes[0][0], use_colorbar=False)<br>        p.set_cmap("bds_highcontrast")<br>        p.set_zlim(rho_min, rho_max)<br>
        #p.modify["velocity"]() # only for close in ones<br>        q = pc.add_projection("RadiationForceMagnitude", ax, weight_field="Density", figure=fig, axes=axes[0][1], use_colorbar=False)<br>
        q.set_log_field(True)<br>        q.set_zlim(rp_min, rp_max)<br>        q.set_cmap("binary")<br>        sp = pf.h.all_data()<br>        if na.any(pf.h.grid_particle_count):<br>            p.modify["particles"](2.0, p_size=1.0, col='k', minimum_mass= 6.e0)<br>
            q.modify["particles"](2.0, p_size=1.0, col='k', minimum_mass= 6.e0)<br>            print "          XXXXX Particles present XXXXX"<br>        Timemyr = pf["InitialTime"]*pf["years"]/1.e6 - firststar*.1<br>
        TotalRP = sp["RadiationForceMagnitude"].sum()<br>        p.modify["text"]((0.051,0.949),"Time = %5.1f Myr" % (Timemyr), text_args = {'color':'k'})<br>        p.modify["text"]((0.05,0.95),"Time = %5.1f Myr" % (Timemyr), text_args = {'color':'w'})<br>
        q.modify["text"]((0.051,0.949),"Total RP =%.4g " % (TotalRP),text_args = {'color':'k'})<br>        q.modify["text"]((0.05,0.95),"Total RP =%.4g " % (TotalRP),text_args = {'color':'w'})<br>
<br>        for p, cax in zip(pc.plots, colorbars):<br>            p._redraw_image()<br>            cbar = cb.Colorbar(cax, p.image, orientation=orient)<br>            p.colorbar = cbar<br>            p._autoset_label()<br>
<br>        fig.savefig(frame_template % (name,ss,ax,n), format="eps")<br><br>