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python-xarray - 基于纬度范围的数据提取

问题描述

>>> dfForecastMSL
<xarray.Dataset>
Dimensions:     (latitude: 1536, longitude: 3072, valid_time: 29)
Coordinates:
    meanSea     int64 0
    time        datetime64[ns] 2020-05-30
  * longitude   (longitude) float64 0.0 0.1172 0.2344 ... 359.6 359.8 359.9
  * latitude    (latitude) float64 89.91 89.79 89.68 ... -89.68 -89.79 -89.91
    step        (valid_time) timedelta64[ns] 0 days 00:00:00 ... 7 days 00:00:00
  * valid_time  (valid_time) datetime64[ns] 2020-05-30 ... 2020-06-06
Data variables:
    msl         (valid_time, latitude, longitude) float32 102246.484 ... 103826.81
Attributes:
    GRIB_edition:            2
    GRIB_centre:             kwbc
    GRIB_centreDescription:  US National Weather Service - NCEP
    GRIB_subCentre:          0
    Conventions:             CF-1.7
    institution:             US National Weather Service - NCEP
    history:                 2020-09-19T07:31:46 GRIB to CDM+CF via cfgrib-0....
>>> dfForecastMSL.history
'2020-09-19T07:31:46 GRIB to CDM+CF via cfgrib-0.9.8.4/ecCodes-2.17.0 with {"source": "/home/NCMRWFTEMP/vsprasad/EXP_HY2B/data/gdasv14/gdas/prodCNTL/gdas.20200530/gdas.t00z.master.grb2f00", "filter_by_keys": {"cfVarName": "msl", "typeOfLevel": "meanSea"}, "encode_cf": ["parameter", "time", "geography", "vertical"]}'

我正在尝试像这样提取我感兴趣的领域。

india = dfForecastMSL.sel(longitude=slice(60,100),latitude=slice(0,40))

输出看起来像....

>>> india = dfForecastMSL.sel(longitude=slice(60,100),latitude=slice(0,40))
>>> india
<xarray.Dataset>
Dimensions:     (latitude: 0, longitude: 342, valid_time: 29)
Coordinates:
    meanSea     int64 0
    time        datetime64[ns] 2020-05-30
  * longitude   (longitude) float64 60.0 60.12 60.23 60.35 ... 99.73 99.84 99.96
  * latitude    (latitude) float64
    step        (valid_time) timedelta64[ns] 0 days 00:00:00 ... 7 days 00:00:00
  * valid_time  (valid_time) datetime64[ns] 2020-05-30 ... 2020-06-06
Data variables:
    msl         (valid_time, latitude, longitude) float32
Attributes:
    GRIB_edition:            2
    GRIB_centre:             kwbc
    GRIB_centreDescription:  US National Weather Service - NCEP
    GRIB_subCentre:          0
    Conventions:             CF-1.7
    institution:             US National Weather Service - NCEP
    history:                 2020-09-19T07:31:46 GRIB to CDM+CF via cfgrib-0....

** 为什么缺少纬度？** 或者我在做wearg 吗？

标签： python-xarray

解决方案

似乎纬度坐标从+90保存到-90，所以按降序排列。切片必须以相同的顺序进行，因此它应该是.sel(latitude=slice(40,0))。

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