具有X，Y坐标的Pandas DataFrame坐标为NumPy矩阵 [英] Pandas DataFrame with X,Y coordinates to NumPy matrix

问题描述

我有一个带有X，Y和value列的DataFrame，例如:

I have a DataFrame with columns X, Y and value, e.g.:

   X |   Y | value
------------------
   1 |   1 |    56
   2 |   1 |    13
   3 |   1 |    25
 ... | ... |   ...
   1 |   2 |     7
   2 |   2 |    18
 ... | ... |   ...
   1 | 123 |    91
 ... | ... |   ...
  50 | 123 |    32

我需要将其转换为DataFrame到NumPy矩阵:

I need to convert this to DataFrame to a NumPy matrix:

[[56, 13, 25, ...],
 [ 7, 18,     ...],
 ...,
 [ 91, ...   , 32]]

我知道我可以遍历DataFrame的每个单元，但这太慢了.有效的方法是什么?

I know I can iterate over each cell of the DataFrame, but that is too slow. What is the effective way of doing this?

还请注意:缺少DataFrame中某些坐标的值

Also note: values for some coordinates in DataFrame are missing

推荐答案

枢纽数据框，并且值应该是您所需要的:

Pivot the data frame and the values should be what you need:

df.pivot('Y', 'X', 'value').values

#array([[ 56.,  13.,  25.,  nan],
#       [  7.,  18.,  nan,  nan],
#       [ 91.,  nan,  nan,  32.]])

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