pandas set_index和reset_index的用法
分类:Python
1.set_index
DataFrame可以通过set_index方法,可以设置单索引和复合索引。
DataFrame.set_index(keys, drop=True, append=False, inplace=False, verify_integrity=False)
append添加新索引,drop为False,inplace为True时,索引将会还原为列
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In [307]: data Out [307]: a b c d 0 bar one z 1.0 1 bar two y 2.0 2 foo one x 3.0 3 foo two w 4.0 In [308]: indexed1 = data.set_index( 'c' ) In [309]: indexed1 Out [309]: a b d c z bar one 1.0 y bar two 2.0 x foo one 3.0 w foo two 4.0 In [310]: indexed2 = data.set_index([ 'a' , 'b' ]) In [311]: indexed2 Out [311]: c d a b bar one z 1.0 two y 2.0 foo one x 3.0 two w 4.0 |
2.reset_index
reset_index可以还原索引,从新变为默认的整型索引
DataFrame.reset_index(level=None, drop=False, inplace=False, col_level=0, col_fill=”)
level控制了具体要还原的那个等级的索引
drop为False则索引列会被还原为普通列,否则会丢失
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In [318]: data Out [318]: c d a b bar one z 1.0 two y 2.0 foo one x 3.0 two w 4.0 In [319]: data.reset_index() Out [319]: a b c d 0 bar one z 1.0 1 bar two y 2.0 2 foo one x 3.0 3 foo two w 4.0 |
转自:https://blog.csdn.net/jingyi130705008/article/details/78162758