July 2018
Intermediate to advanced
596 pages
13h 35m
Japanese
Content preview from Pythonによるデータ分析入門 第2版 ―NumPy、pandasを使ったデータ処理
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10.2
データの集約
327
10.2.1
列に複数の関数を適用する
ここで、前に説明に使ったチップ情報のデータに戻りましょう。このデータを
read_csv
で読み込ん
だ後、チップの割合を示す列
tip_pct
を追加します。
In [57]: tips = pd.read_csv('examples/tips.csv')
#
総支払額に占めるチップの割合を追加
In [58]: tips['tip_pct'] = tips['tip'] / tips['total_bill']
In [59]: tips[:6]
Out[59]:
total_bill tip smoker day time size tip_pct
0 16.99 1.01 No Sun Dinner 2 0.059447
1 10.34 1.66 No Sun
Dinner 3 0.160542
2 21.01 3.50 No Sun Dinner 3 0.166587
3 23.68 3.31 No Sun Dinner 2 0.139780
4 24.59 3.61 No Sun Dinner 4 0.146808
5 25.29 4.71 No Sun Dinner 4 0.186240
これまで見てきたように、シリーズやデータフレームのすべての列を集約するということは、つまり、
適用したい関数を
aggregate
メソッドに渡したり、
mean
や
std
などのメソッドを呼んだりすることです。
しかし、列ごとに異なる関数を使って集約したい
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