pandas :删除包含所有NaN的列 [英] Pandas: drop columns with all NaN's

问题描述

我意识到从数据帧中删除NaN就像df.dropna一样容易，但是由于某些原因，这对我的工作不起作用，我不确定为什么.

I realize that dropping NaNs from a dataframe is as easy as df.dropna but for some reason that isn't working on mine and I'm not sure why.

这是我的原始数据框:

fish_frame1:                       0   1   2         3   4       5   6          7
0               #0915-8 NaN NaN       NaN NaN     NaN NaN        NaN
1                   NaN NaN NaN  LIVE WGT NaN  AMOUNT NaN      TOTAL
2               GBW COD NaN NaN     2,280 NaN   $0.60 NaN  $1,368.00
3               POLLOCK NaN NaN     1,611 NaN   $0.01 NaN     $16.11
4                 WHAKE NaN NaN       441 NaN   $0.70 NaN    $308.70
5           GBE HADDOCK NaN NaN     2,788 NaN   $0.01 NaN     $27.88
6           GBW HADDOCK NaN NaN    16,667 NaN   $0.01 NaN    $166.67
7               REDFISH NaN NaN       932 NaN   $0.01 NaN      $9.32
8    GB WINTER FLOUNDER NaN NaN       145 NaN   $0.25 NaN     $36.25
9   GOM WINTER FLOUNDER NaN NaN    25,070 NaN   $0.35 NaN  $8,774.50
10        GB YELLOWTAIL NaN NaN        26 NaN   $1.75 NaN     $45.50

下面的代码是尝试删除所有NaN以及超过3个NaN的任何列(我认为一个或两个都应该起作用):

The code that follows is an attempt to drop all NaNs as well as any columns with more than 3 NaNs (either one, or both, should work I think):

fish_frame.dropna()
fish_frame.dropna(thresh=len(fish_frame) - 3, axis=1)

这将产生:

fish_frame1 after dropna:                       0   1   2         3   4       5   6          7
0               #0915-8 NaN NaN       NaN NaN     NaN NaN        NaN
1                   NaN NaN NaN  LIVE WGT NaN  AMOUNT NaN      TOTAL
2               GBW COD NaN NaN     2,280 NaN   $0.60 NaN  $1,368.00
3               POLLOCK NaN NaN     1,611 NaN   $0.01 NaN     $16.11
4                 WHAKE NaN NaN       441 NaN   $0.70 NaN    $308.70
5           GBE HADDOCK NaN NaN     2,788 NaN   $0.01 NaN     $27.88
6           GBW HADDOCK NaN NaN    16,667 NaN   $0.01 NaN    $166.67
7               REDFISH NaN NaN       932 NaN   $0.01 NaN      $9.32
8    GB WINTER FLOUNDER NaN NaN       145 NaN   $0.25 NaN     $36.25
9   GOM WINTER FLOUNDER NaN NaN    25,070 NaN   $0.35 NaN  $8,774.50
10        GB YELLOWTAIL NaN NaN        26 NaN   $1.75 NaN     $45.50

我是Pandas的新手，所以我不确定这是行不通的，因为我做错了什么，或者我误解了某些事情或滥用了命令.任何帮助表示赞赏，谢谢.

I am a novice with Pandas so I'm not sure if this isn't working because I'm doing something wrong or I'm misunderstanding something or misusing a command. Any help is appreciated thanks.

推荐答案

来自dropna文档字符串:

    # drop the columns where all elements are NaN:

    >>> df.dropna(axis=1, how='all')
         A    B  D
    0  NaN  2.0  0
    1  3.0  4.0  1
    2  NaN  NaN  5

这篇关于 pandas :删除包含所有NaN的列的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！