New issue 1340: create_profile returns zero-value profile when input field is negative https://bitbucket.org/yt_analysis/yt/issues/1340/create_profile-returns-zero... Suoqing Ji: The test script generates a particle dataset with negative velocities. Velocity profile created from this dataset is zero. This also causes problems in ``ParticlePlot``. ``` #!python import yt import numpy as np n_particles = int(1e4) ppx, ppy, ppz = np.random.normal(size=[3, n_particles]) pvx, pvy, pvz = - np.ones((3, n_particles)) data = {'particle_position_x': ppx, 'particle_position_y': ppy, 'particle_position_z': ppz, 'particle_velocity_x': pvx, 'particle_velocity_y': pvy, 'particle_velocity_z': pvz} bbox = 1.1*np.array([[min(ppx), max(ppx)], [min(ppy), max(ppy)], [min(ppz), max(ppz)]]) ds = yt.load_particles(data, bbox=bbox) ad = ds.all_data() print (ad['particle_velocity_x'].max(), ad['particle_velocity_x'].min()) profile = yt.create_profile(ad, ["particle_position_x", "particle_position_y"], "particle_velocity_x", weight_field=None) print (profile["particle_velocity_x"].max(), profile["particle_velocity_x"].min()) ```