June 2024
Intermediate to advanced
200 pages
4h 46m
Japanese
Content preview from Python2年生 データ分析のしくみ 第2版 体験してわかる！会話でまなべる！
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Chapter
2
74
やみくもに重複を削除しない
今回は機械的に重複するデータを削除しましたが、データによっては偶然
にまったく同じ値の行が存在することも考えられます。そのような種類の
データではないかどうかは、自分で考えましょう。
CAUTION
文字列型のデータを数値に変換する
用意されたデータは、それぞれの作者によってデータ形式が違います。「数値のデータなの
に文字列で用意されている場合」もあります。そういうデータで計算したいときは、データ
の種類を数値型に変換しておく必要があります。
まずは、わざと数値を文字列型で作ったデータフレームを作ってみましょう（リスト
2.36）。
import pandas as pd
data = {
"A" : ["100","300"],
"B" : ["500","1,500"]
}
dfA = pd.DataFrame(data)
dfA
【入力プログラム】リスト 2.36
出力結果
まずはこのデータから
変換を試していこう！
75
データのミスをチェックする
LESSON
07
各列のデータの種類を調べてみます（リスト2.37）。
dfA.dtypes
A object
B object
dtype: object
すべて文字列型だとわかります。そこで、データの型を整数型に変換しましょう。 ...
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