Created
May 23, 2019 18:15
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NetCDF to MP4 demo
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| import numpy as np | |
| import xarray as xr | |
| import cv2 | |
| import imageio | |
| def to_rgb(data, vmin=None, vmax=None, size=None, pmin=2, pmax=98, mask=None): | |
| if isinstance(data, list): | |
| n_channels = len(data) | |
| elif isinstance(data, xr.DataArray): | |
| n_channels = 1 | |
| data = [data] | |
| else: | |
| raise ValueError() | |
| values = [np.asarray(d) for d in data] | |
| shape = data[0].shape + (n_channels,) | |
| if vmin is not None: | |
| if isinstance(vmin, (int, float)): | |
| vmin = [vmin] * n_channels | |
| if vmax is not None: | |
| if isinstance(vmax, (int, float)): | |
| vmax = [vmax] * n_channels | |
| im = np.empty(shape) | |
| for i in range(n_channels): | |
| channel = values[i] | |
| if vmin is not None: | |
| minval = vmin[i] | |
| else: | |
| minval = np.percentile(channel, pmin) | |
| if vmax is not None: | |
| maxval = vmax[i] | |
| else: | |
| maxval = np.percentile(channel, pmax) | |
| if maxval > minval: | |
| channel = (channel - minval) / (maxval - minval) * 255 | |
| im[:, :, i] = channel | |
| im = np.clip(im, 0, 255).astype(np.uint8) | |
| if n_channels == 1: | |
| colored = cv2.cvtColor(im[:, :, 0], cv2.COLOR_GRAY2BGR) | |
| else: | |
| colored = cv2.cvtColor(im, cv2.COLOR_RGB2BGR) | |
| if mask is not None: | |
| colored[~mask] = 0 | |
| if size is not None: | |
| if size[0] is None: | |
| size = (int(colored.shape[0] * size[1] / colored.shape[1]), size[1]) | |
| elif size[1] is None: | |
| size = (size[0], int(colored.shape[1] * size[0] / colored.shape[0])) | |
| colored = cv2.resize(colored, (size[1], size[0])) | |
| return cv2.cvtColor(colored, cv2.COLOR_BGR2RGB) | |
| filenames = ['2014_01_01_2m_temperature.nc', | |
| '2014_01_01_100m_u_component_of_wind.nc', | |
| '2014_01_01_100m_v_component_of_wind.nc'] | |
| da = xr.open_mfdataset(filenames, concat_dim='time').to_array() | |
| with imageio.get_writer('result.mp4', codec='libx264') as writer: | |
| for t in da.time.values: | |
| data = [] | |
| for name in ['t2m', 'u100', 'v100']: | |
| data.append(da.sel(time=t, variable=name)) | |
| frame = to_rgb(data) | |
| writer.append_data(frame) |
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