data ={'a':[11,22,33,44],'b':['aa','bb','cc','dd'],'c':[9,8,7,6],'d':[1,2,3,4]}
df = DataFrame(data)
df
a
b
c
d
0
11
aa
9
1
1
22
bb
8
2
2
33
cc
7
3
3
44
dd
6
4
iloc：通过行/列号选取数据
df.iloc[0]#选取第0行数据
a 11
b aa
c 9
d 1
Name: 0, dtype: object
df.iloc[0:2]#选取多行
a
b
c
d
0
11
aa
9
1
1
22
bb
8
2
df.iloc[:,[1]]#也可以按照列号选取某列 选取第2列
b
0
aa
1
bb
2
cc
3
dd
df.iloc[0:1,[1]]#可以按照行号选取某行某列 选取第0行 第2列
b
0
aa
df.iloc[0:2,[0,1]]#可以按照行号选取多行多列 选取第0~2行 第0～2列
a
b
0
11
aa
1
22
bb
loc通过标签选取数据
df.loc[0]#选取第1行 因为第1行的行号是0所以和iloc效果相同
a 11
b aa
c 9
d 1
Name: 0, dtype: object
data ={'a':[11,22,33,44],'b':['aa','bb','cc','dd'],'c':[9,8,7,6],'d':[1,2,3,4]}
df1 = DataFrame(data,index =['a','b','c','d'])
df1
a
b
c
d
a
11
aa
9
1
b
22
bb
8
2
c
33
cc
7
3
d
44
dd
6
4
df1.loc['b']#选取第b行
a 22
b bb
c 8
d 2
Name: b, dtype: object
df1.loc['b':]#选取多行
a
b
c
d
b
22
bb
8
2
c
33
cc
7
3
d
44
dd
6
4
df1.loc[:,['a']]#通过标签选取某列
a
a
11
b
22
c
33
d
44
df1.loc[:,['a','b']]#通过标签选取多列
a
b
a
11
aa
b
22
bb
c
33
cc
d
44
dd
df1.loc['a',['b','c']]#通过标签选取某行某列
b aa
c 9
Name: a, dtype: object
按照条件选取数据
df1.loc[df1['a']==11]#通过单个条件选取数据
a
b
c
d
a
11
aa
9
1
df1.loc[(df1['a']==11)&(df1['d']==1)]#通过单多个条件选取数据
a
b
c
d
a
11
aa
9
1
ix 简单粗暴 混合使用
也就是说 ix把iloc和loc语法综合了，爱用哪个用哪个，不过会报个warning
df #再看下dataframe
a
b
c
d
0
11
aa
9
1
1
22
bb
8
2
2
33
cc
7
3
3
44
dd
6
4
df.ix[1]#可以像iloc通过行号选取
/Users/anaconda/anaconda3/lib/python3.7/site-packages/ipykernel_launcher.py:1: FutureWarning:
.ix is deprecated. Please use
.loc for label based indexing or
.iloc for positional indexing
See the documentation here:
http://pandas.pydata.org/pandas-docs/stable/user_guide/indexing.html#ix-indexer-is-deprecated
"""Entry point for launching an IPython kernel.
a 22
b bb
c 8
d 2
Name: 1, dtype: object
df1
a
b
c
d
a
11
aa
9
1
b
22
bb
8
2
c
33
cc
7
3
d
44
dd
6
4
df1.ix['a']#可以像loc通过标签选取
/Users/anaconda/anaconda3/lib/python3.7/site-packages/ipykernel_launcher.py:1: FutureWarning:
.ix is deprecated. Please use
.loc for label based indexing or
.iloc for positional indexing
See the documentation here:
http://pandas.pydata.org/pandas-docs/stable/user_guide/indexing.html#ix-indexer-is-deprecated
"""Entry point for launching an IPython kernel.
a 11
b aa
c 9
d 1
Name: a, dtype: object
df1.ix[3,3]#通过行号选取指定位置的数据
/Users/anaconda/anaconda3/lib/python3.7/site-packages/ipykernel_launcher.py:1: FutureWarning:
.ix is deprecated. Please use
.loc for label based indexing or
.iloc for positional indexing
See the documentation here:
http://pandas.pydata.org/pandas-docs/stable/user_guide/indexing.html#ix-indexer-is-deprecated
"""Entry point for launching an IPython kernel.
/Users/anaconda/anaconda3/lib/python3.7/site-packages/pandas/core/indexing.py:961: FutureWarning:
.ix is deprecated. Please use
.loc for label based indexing or
.iloc for positional indexing
See the documentation here:
http://pandas.pydata.org/pandas-docs/stable/user_guide/indexing.html#ix-indexer-is-deprecated
return getattr(section, self.name)[new_key]
4
df1.ix['a','a']#通过标签选取指定位置的数据
/Users/anaconda/anaconda3/lib/python3.7/site-packages/ipykernel_launcher.py:1: FutureWarning:
.ix is deprecated. Please use
.loc for label based indexing or
.iloc for positional indexing
See the documentation here:
http://pandas.pydata.org/pandas-docs/stable/user_guide/indexing.html#ix-indexer-is-deprecated
"""Entry point for launching an IPython kernel.
11