Python 仅当行值为特定字符串时,才删除具有重复列名的列
我需要删除名称重复的列,但只删除所有行值都为“nan”(作为字符串,而不是nan)的重复列。下面是示例数据和预期输出。非常感谢Python 仅当行值为特定字符串时,才删除具有重复列名的列,python,pandas,duplicates,drop,Python,Pandas,Duplicates,Drop,我需要删除名称重复的列,但只删除所有行值都为“nan”(作为字符串,而不是nan)的重复列。下面是示例数据和预期输出。非常感谢 df = pd.DataFrame({'id':[1,2,3,4],'a':[0,0,0,'nan'], 'b':['nan','nan','nan','nan'], 'c':['nan','nan','nan','nan'], 'd':[1,'nan',0,2]}) df = df.rename(columns = {'a':'a','b':'a', 'c':'b'
df = pd.DataFrame({'id':[1,2,3,4],'a':[0,0,0,'nan'], 'b':['nan','nan','nan','nan'], 'c':['nan','nan','nan','nan'], 'd':[1,'nan',0,2]})
df = df.rename(columns = {'a':'a','b':'a', 'c':'b', 'd':'b'})
id a a b b
0 1 0 nan nan 1
1 2 0 nan nan nan
2 3 0 nan nan 0
3 4 nan nan nan 2
预期产量
id a b
0 1 0 1
1 2 0 nan
2 3 0 0
3 4 nan 2
问题是,如果要保留空的但唯一的列。如果没有,您可以在一行中解决它:
df1=df.dropna(how='all',axis='columns')
如果您想保留它们,您可以删除它们,然后重新创建它们,因为它们实际上是空的
输入:
df = pd.DataFrame({'id':[1,2,3,4],'a':[0,0,0,np.nan], 'b':[np.nan,np.nan,np.nan,np.nan], 'c':[np.nan,np.nan,np.nan,np.nan], 'd':[1,np.nan,0,2], 'e':[np.nan,np.nan,np.nan,np.nan]})
df = df.rename(columns = {'a':'a','b':'a', 'c':'b', 'd':'b'})
代码:
输出:
.dropna(how='all',axis='columns')
?
df1 = df.dropna(how='all', axis='columns').copy()
df1[list(df.columns.difference(df1.columns))] = np.nan
# id a b e
# 0 1 0.0 1.0 NaN
# 1 2 0.0 NaN NaN
# 2 3 0.0 0.0 NaN
# 3 4 NaN 2.0 NaN