英文:
Writing a tiff with colormap from rasterio
问题
以下是您要翻译的代码部分：
import xarray as xrimport rioxarrayimport cftimeimport osimport datetimefrom rasterio.enums import Resamplingimport matplotlib.pyplot as pltds_input = "inputfile.nc"operatingdir = '\\'filename = ds_input[:-3]# determine the maximum number of bands in the raster using the band name in position 0 of the common_key listbandcount = 7# create a colormap for the output raster, with 5 colour bandscmap = plt.cm.get_cmap('viridis', 5)# use a for loop to output each day of the forecastfor i in range(0, bandcount):# Convert ds_netcdf_interp to raster using the max fbi valuesds_input.var_name.rio.to_raster('{}\\Output\\{}_number{}.tif'.format(operatingdir, filename, i),windowed=True,compress='lzw',dtype='int16',nodata=-9999,overwrite=True,tiled=True,cloud_optimized=True,driver='COG',colormap=cmap)
希望这对您有所帮助。
英文:
I'm writing a single band tif using the code below. What I'm most interested in doing is writing a colormap for band 0 along with the tiff.
The code below is iterating through some other files and is successfully writing out each band of each input. I would like to be able to apply a colormap to each output. Below I'm trying to ask for viridis to be limited to 5 categories.
I would like to avoid explicitly avoid importing GDAL - and this seems entirely possible.
So my question is:
How do I write out the file with the viridis colormap applied to it? If necessary, apply on band[0]
import xarray as xrimport rioxarrayimport cftimeimport osimport datetimefrom rasterio.enums import Resamplingimport matplotlib.pyplot as pltds_input = "inputfile.nc"operatingdir = '\\'filename = ds_input[:-3]#determine the maximum number of bands in the raster using the band name in position 0 of the common_key listbandcount = 7#create a colormap for the output raster, with 5 colour bandscmap = plt.cm.get_cmap('viridis', 5)#use a for loop to output each day of the forecastfor i in range(0, bandcount):#Convert ds_netcdf_interp to raster using the max fbi valuesds_input.var_name.rio.to_raster('{}\\Output\\{}_number{}.tif'.format(operatingdir, filename, i),windowed=True,compress='lzw',dtype='int16',nodata=-9999,overwrite=True,tiled=True,cloud_optimized=True,driver='COG',colormap=cmap)
答案1
得分: 1
你可以使用rasterio的write_colormap()方法将色彩映射写入TIFF文件。以下是如何从文档中使用的简短示例：
import rasteriowith rasterio.Env():with rasterio.open('tests/data/shade.tif') as src:shade = src.read(1)meta = src.metawith rasterio.open('/tmp/colormap.tif', 'w', **meta) as dst:dst.write(shade, indexes=1)dst.write_colormap(1, {0: (255, 0, 0, 255),255: (0, 0, 255, 255) })cmap = dst.colormap(1)# Trueassert cmap[0] == (255, 0, 0, 255)# Trueassert cmap[255] == (0, 0, 255, 255)
基本上，write_colormap方法接受带号作为第一个参数，然后是以栅格值为键、其对应的RGBA值为值的字典。
英文:
You can write a colormap to a tiff file using rasterios write_colormap(). Here's a short example on how to use it from the documentation:
import rasteriowith rasterio.Env():with rasterio.open('tests/data/shade.tif') as src:shade = src.read(1)meta = src.metawith rasterio.open('/tmp/colormap.tif', 'w', **meta) as dst:dst.write(shade, indexes=1)dst.write_colormap(1, {0: (255, 0, 0, 255),255: (0, 0, 255, 255) })cmap = dst.colormap(1)# Trueassert cmap[0] == (255, 0, 0, 255)# Trueassert cmap[255] == (0, 0, 255, 255)
Basically write_colormap takes the band number as the first argument and then a dictionary of raster value as keys and their corresponding RGBA values as values.
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