pandas实例-Deleting（二）

继续前面的练习，之前的文章参考：

• pandas实例-了解你的数据-Chipotle
• pandas实例-筛选与排序-Chipotle
• pandas实例-数据可视化-Chipotle
• pandas实例-了解你的数据-Occupation
• pandas实例-筛选与过滤-Euro 12
• pandas实例-筛选与过滤-Fictional Army
• pandas实例-聚合-Alcohol Consumption
• pandas实例-聚合-Occupation
• pandas实例-聚合-Regiment
• pandas实例-Apply-Student Alcohol Consumption
• pandas实例-Apply-Crime Rates
• pandas实例-Merge-MPG Cars
• pandas实例-Merge-Fictitious Names
• pandas实例-merge-House Market
• pandas实例-Stats-US_Baby_Names
• pandas实例-Stats-Wind Statistics
• pandas实例-Visualization-Titanic_Desaster
• pandas实例-Visualization-Scores
• pandas实例-Visualization-Online Retail
• pandas实例-Visualization-Tips
• pandas实例-Time Series-Apple Stock

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先看数据集

url = 'https://archive.ics.uci.edu/ml/machine-learning-databases/wine/wine.data'
df = pd.read_csv(url)

1. Delete the first, fourth, seventh, nineth, eleventh, thirteenth and fourteenth columns

删除某些列

drops = pd.Series([1,4,7,9,11,13,14])
df.columns[drops-1]

df.drop(columns=df.columns[drops-1] , inplace=True)

2. Assign the columns as below:

这一题，就是指定列名，直接来吧，但是有个问题，就是当前的column就没了，这里占位的其实是数据

df.columns=['alcohol', 'malic_acid', 'alcalinity_of_ash', 'magnesium', 'flavanoids', 'proanthocyanins', 'hue']

3. Set the values of the first 3 rows from alcohol as NaN

##  Set the values of the first 3 rows from alcohol as NaN
df.iloc[:3] = np.nan

4. Now set the value of the rows 3 and 4 of magnesium as NaN

# Now set the value of the rows 3 and 4 of magnesium as NaN
df.loc[3:5 , 'magnesium'] = np.nan

哦，上一题我做错了，哈哈哈，我把所有列都设置为nan了

5. Fill the value of NaN with the number 10 in alcohol and 100 in magnesium

df['alcohol'].fillna(10 , inplace=True)
df['magnesium'].fillna(100 , inplace=True)

6. Count the number of missing values

df.isna().sum()

我这里是有缺失值的，但是原文没有，注意下

后面还有几题，我看比较类似，就算了，到这吧，哈