August 2017
Intermediate to advanced
500 pages
12h 3m
Japanese
Content preview from PythonとJavaScriptではじめるデータビジュアライゼーション
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201
9.3 インデックスと pandas のデータ選択
行
/
列形式のインデックス付けはわかったと思うので、
DataFrame
のスライスを選択してみま
しょう。
DataFrame
の列はドット表記（名前に空白や特殊文字がない場合）か角括弧表記で選択し
ます。これを
born_in
列で確認してみましょう。
bi_col = df.born_in #
または
bi = df['born_in']
bi_col
Out:
0
1 Bosnia and Herzegovina
2 Bosnia and Herzegovina
3
...
1051
Name: born_in, Length: 1052, dtype: object
type(bi_col)
Out: pandas.core.series.Series
列の選択では
pandas
の
Series
を返し、
DataFrame
のインデックスは維持されます。
DataFrame
と
Series
は、同じメソッドを使って行やメンバーにアクセスします。
iloc
は数値イ
ンデックス（
DataFrame
内の値を表すための位置）で選択し、
loc
はラベルで選択します。
ix
はラ
ベルで選択しますが、数値インデックスも使えます。この例では、ラベルによるアクセスだけをサ
ポートしています。
iloc
を明示的に使って位置を指定します。
#
最初の行にアクセスする
df.iloc[0] #
または
df.ix[0]
Out:
name César Milstein
born_in
category Physiology ...
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