根据列值重新排序数据帧行(Reorder dataframe rows based on column values)

 我有这个pandas数据帧： 
 
        artist               track   class1  class2     class3
0   Portishead               Roads   0.00    1.00          0.0
1  Yo La Tengo     Our Way to Fall   0.14    0.86          0.0
2    Radiohead  Fake Plastic Trees   0.03    0.97          0.0
 
 和这两个用户输入变量： 
 
 input_value = 0.80
 input_class = 'class2'
 
 从这些变量中我想迭代数据帧，在所选的class2找到与input_value最接近的值，并重新排序数据帧行，如下所示： 
 
        artist               track   class1  class2     class3
1  Yo La Tengo     Our Way to Fall   0.14    0.86          0.0
2    Radiohead  Fake Plastic Trees   0.03    0.97          0.0
0   Portishead               Roads   0.00    1.00          0.0
 
 class2值的接近程度决定了行的顺序。 
 
 （ 0.86最接近0.97秒，依此类推......） 
 
 到目前为止，我只找到了最接近的值，使用以下代码： 
 
for col in df.ix[:,'class1':'class3']:
    if col == input_class:
        print min(df[col] - input_value)
 
 但我离目标还有点远。 任何人都能指出我正确的方向吗？ 

I have this pandas dataframe:
 
        artist               track   class1  class2     class3
0   Portishead               Roads   0.00    1.00          0.0
1  Yo La Tengo     Our Way to Fall   0.14    0.86          0.0
2    Radiohead  Fake Plastic Trees   0.03    0.97          0.0
 
and these two user input variables:
 
 input_value = 0.80
 input_class = 'class2'
 
from those variables I would like to iterate over the dataframe, find the closest value to input_valuein chosen class2, and re-order dataframe rows, like so:
 
        artist               track   class1  class2     class3
1  Yo La Tengo     Our Way to Fall   0.14    0.86          0.0
2    Radiohead  Fake Plastic Trees   0.03    0.97          0.0
0   Portishead               Roads   0.00    1.00          0.0
 
where the closeness of class2 values determines the order of rows. 
 
(0.86 being the closest to 0.80, 0.97 second to that and so on..)
 
so far I have only found the closest value, with the following code:
 
for col in df.ix[:,'class1':'class3']:
    if col == input_class:
        print min(df[col] - input_value)
 
but I'm still a bit far from my goal. can anyone point me in the right direction?

原文：https://stackoverflow.com/questions/46556434