《使用pandas进行数据分析》网课笔记（7到12）

七. How do I sort a Pandas Dataframe or a Series

# coding: utf-8

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import pandas as pd


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movies = pd.read_csv('http://bit.ly/imdbratings')


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movies.head()


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movies['title'].sort_values(ascending = False)


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#ascending = False 使得其降序排列
movies.sort_values('star_rating', ascending = False)


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movies.sort_values(['star_rating', 'duration'])

八. How do I filter rows of pandas Dataframe by column value

# coding: utf-8

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import pandas as pd


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movies = pd.read_csv('http://bit.ly/imdbratings')


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movies.head()


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movies.shape


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type(True)


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booleans = []
for length in movies.duration:
    if length >= 200:
        booleans.append(True)
    else:
        booleans.append(False)


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booleans[0:5]


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len(booleans)


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#is_long = pd.Series(booleans)


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is_long = movies.duration >= 200
is_long.head()


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#Here it only shows the movies with no less than 200 duration
#movies[is_long]
#或者替代方法
#movies.loc[movies.duration >= 200 ,'genre']
#又或者替代方法
movies[movies.duration >= 200]['genre']

九. How do I apply multiple filter criteria to a Pandas Dataframe

# coding: utf-8

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import pandas as pd


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movies = pd.read_csv('http://bit.ly/imdbratings')


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movies.head()


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movies[movies.duration >= 200]


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movies[(movies.duration >= 200) & (movies.genre == 'Drama')]


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movies[(movies.genre == 'Drama') | (movies.genre == 'Drama')]

十. Your Pandas Questions answered

# coding: utf-8

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import pandas as pd


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ufo = pd.read_csv('http://bit.ly/uforeports')


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ufo.columns


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ufo = pd.read_csv('http://bit.ly/uforeports',usecols=[0,4])
ufo.columns


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ufo = pd.read_csv('http://bit.ly/uforeports',nrows = 3)
ufo


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for c in ufo.City:
    print(c)


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for index, row in ufo.iterrows():
    print(index, row.City, row.State)


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#The best way to drop every non-numeric column for a dataframe
drinks = pd.read_csv('http://bit.ly/drinksbycountry')


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drinks.dtypes


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import numpy as np
drinks.select_dtypes(include =[np.number]).dtypes


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drinks.describe()

十一. How do I use 'axis' parameter in Pandas

# coding: utf-8

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import pandas as pd


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drinks = pd.read_csv('http://bit.ly/drinksbycountry')


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drinks.head()


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drinks.drop('continent',axis=1).head()


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drinks.drop(2,axis=0).head()


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#这里是因为，默认的设置是drinks.mean(axis = 0)
drinks.mean()


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drinks.mean(axis = 1)


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drinks.mean(axis = 0).shape

十二. How do I use string methods in Pandas

# coding: utf-8

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'hello'.upper()


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import pandas as pd


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orders = pd.read_table('http://bit.ly/chiporders')


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orders.head()


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orders.choice_description.str.replace('[','').str.replace(']','')


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orders[orders.item_name.str.contains('Chicken')]