Question

我有一个xarray数据集，其中包含三个单独的4x4矩阵，当前填充有随机值。

我可以屏蔽每个4x4矩阵，以便所有等于0的值都是nan，我想用下一个矩阵向下的值替换这些nan值。

最终它将扩展到非常大的卫星图像阵列，以便我可以执行搜索并根据“最后的最佳像素”创建图像。以下是我当前用于参考的代码：

host.0: "m"
host.1: "a"
host.2: "x"
information.creation_utctime: "1494831805258"
information.data_id: "11138"
information.data_size: 186497
information.type: "image/jpeg"
roll.0: "1"
roll.1: "1"
roll.2: "1"
roll.3: "3"
roll.4: "8"
subhost.0: "s"
subhost.1: "a"
subhost.2: "m"
subhost.3: "p"
subhost.4: "l"
subhost.5: "e"
urls.0: "h"
urls.1: "t"
urls.10: "a"
urls.11: "l"
urls.12: "h"
urls.13: "o"
urls.14: "s"
urls.15: "t"
urls.16: ":"
urls.17: "9"
urls.18: "6"
urls.19: "1"
urls.2: "t"
urls.20: "8"
urls.21: "/"
urls.22: "i"
urls.23: "n"
urls.24: "f"
urls.25: "o"
urls.26: "?"
urls.27: "d"
urls.28: "a"
urls.29: "t"
urls.3: "p"
urls.30: "a"
urls.31: "_"
urls.32: "i"
urls.33: "d"
urls.34: "="
urls.35: "1"
urls.36: "1"
urls.37: "1"
urls.38: "3"
urls.39: "8"
urls.4: ":"
urls.5: "/"
urls.6: "/"
urls.7: "l"
urls.8: "o"
urls.9: "c"
_id: "11138"

我想做的是将b中任何被屏蔽为False的值替换为与“ 2017-10-12”相对应的4x4矩阵中的值。任何帮助，将不胜感激。

Answer 1

您可以使用ffill()和bfill()方法（例如，

import numpy as np
import xarray as xr

dval = np.random.RandomState(0).randint(5,size=[3,4,4])

x = [0,1,2,3]
y = [0,1,2,3]
time = ['2017-10-13','2017-10-12','2017-10-11']

a = xr.DataArray(dval,coords=[time,x,y],dims=['time','x','y'])
a = a.where(a > 0)
filled = a.bfill('time')

结果：

>>> a
<xarray.DataArray (time: 3, x: 4, y: 4)>
array([[[ 4., nan,  3.,  3.],
        [ 3.,  1.,  3.,  2.],
        [ 4., nan, nan,  4.],
        [ 2.,  1., nan,  1.]],

       [[ 1., nan,  1.,  4.],
        [ 3., nan,  3., nan],
        [ 2.,  3., nan,  1.],
        [ 3.,  3.,  3., nan]],

       [[ 1.,  1.,  1., nan],
        [ 2.,  4.,  3.,  3.],
        [ 2.,  4.,  2., nan],
        [nan,  4., nan,  4.]]])
Coordinates:
  * time     (time) <U10 '2017-10-13' '2017-10-12' '2017-10-11'
  * x        (x) int64 0 1 2 3
  * y        (y) int64 0 1 2 3

>>> filled
<xarray.DataArray (time: 3, x: 4, y: 4)>
array([[[ 4.,  1.,  3.,  3.],
        [ 3.,  1.,  3.,  2.],
        [ 4.,  3.,  2.,  4.],
        [ 2.,  1.,  3.,  1.]],

       [[ 1.,  1.,  1.,  4.],
        [ 3.,  4.,  3.,  3.],
        [ 2.,  3.,  2.,  1.],
        [ 3.,  3.,  3.,  4.]],

       [[ 1.,  1.,  1., nan],
        [ 2.,  4.,  3.,  3.],
        [ 2.,  4.,  2., nan],
        [nan,  4., nan,  4.]]])
Coordinates:
  * time     (time) <U10 '2017-10-13' '2017-10-12' '2017-10-11'
  * x        (x) int64 0 1 2 3
  * y        (y) int64 0 1 2 3

相关的interpolate_na()方法在这些情况下也很方便（但在这种情况下不是这样）。

在XArray中替换零值

1 个答案: