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数据分析实际案例之：pandas在泰坦尼特号乘客数据中的使用

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目录
  • 简介
  • 泰坦尼特号乘客数据
  • 使用pandas对数据进行分析
    • 引入依赖包
    • 读取和分析数据
  • 图形化表示和矩阵转换

简介

1912年4月15日，号称永不沉没的泰坦尼克号因为和冰山相撞沉没了。因为没有足够的救援设备，2224个乘客中有1502个乘客不幸遇难。事故已经发生了，但是我们可以从泰坦尼克号中的历史数据中发现一些数据规律吗？今天本文将会带领大家灵活的使用pandas来进行数据分析。

泰坦尼特号乘客数据

我们从kaggle官网中下载了部分泰坦尼特号的乘客数据，主要包含下面几个字段：

变量名 含义 取值
survival 是否生还 0 = No, 1 = Yes
pclass 船票的级别 1 = 1st, 2 = 2nd, 3 = 3rd
sex 性别
Age 年龄
sibsp 配偶信息
parch 父母或者子女信息
ticket 船票编码
fare 船费
cabin 客舱编号
embarked 登录的港口 C = Cherbourg, Q = Queenstown, S = Southampton

下载下来的文件是一个csv文件。接下来我们来看一下怎么使用pandas来对其进行数据分析。

使用pandas对数据进行分析

引入依赖包

本文主要使用pandas和matplotlib，所以需要首先进行下面的通用设置： 

from numpy.random import randn

import numpy as np

np.random.seed(123)

import os

import matplotlib.pyplot as plt

import pandas as pd

plt.rc('figure', figsize=(10, 6))

np.set_printoptions(precision=4)

pd.options.display.max_rows = 20

读取和分析数据

pandas提供了一个read_csv方法可以很方便的读取一个csv数据，并将其转换为DataFrame： 

path = '../data/titanic.csv'

df = pd.read_csv(path)

df

我们看下读入的数据：

PassengerId Pclass Name Sex Age SibSp Parch Ticket Fare Cabin Embarked
0 892 3 Kelly, Mr. James male 34.5 0 0 330911 7.8292 NaN Q
1 893 3 Wilkes, Mrs. James (Ellen Needs) female 47.0 1 0 363272 7.0000 NaN S
2 894 2 Myles, Mr. Thomas Francis male 62.0 0 0 240276 9.6875 NaN Q
3 895 3 Wirz, Mr. Albert male 27.0 0 0 315154 8.6625 NaN S
4 896 3 Hirvonen, Mrs. Alexander (Helga E Lindqvist) female 22.0 1 1 3101298 12.2875 NaN S
5 897 3 Svensson, Mr. Johan Cervin male 14.0 0 0 7538 9.2250 NaN S
6 898 3 Connolly, Miss. Kate female 30.0 0 0 330972 7.6292 NaN Q
7 899 2 Caldwell, Mr. Albert Francis male 26.0 1 1 248738 29.0000 NaN S
8 900 3 Abrahim, Mrs. Joseph (Sophie Halaut Easu) female 18.0 0 0 2657 7.2292 NaN C
9 901 3 Davies, Mr. John Samuel male 21.0 2 0 A/4 48871 24.1500 NaN S
... ... ... ... ... ... ... ... ... ... ... ...
408 1300 3 Riordan, Miss. Johanna Hannah"" female NaN 0 0 334915 7.7208 NaN Q
409 1301 3 Peacock, Miss. Treasteall female 3.0 1 1 SOTON/O.Q. 3101315 13.7750 NaN S
410 1302 3 Naughton, Miss. Hannah female NaN 0 0 365237 7.7500 NaN Q
411 1303 1 Minahan, Mrs. William Edward (Lillian E Thorpe) female 37.0 1 0 19928 90.0000 C78 Q
412 1304 3 Henriksson, Miss. Jenny Lovisa female 28.0 0 0 347086 7.7750 NaN S
413 1305 3 Spector, Mr. Woolf male NaN 0 0 A.5. 3236 8.0500 NaN S
414 1306 1 Oliva y Ocana, Dona. Fermina female 39.0 0 0 PC 17758 108.9000 C105 C
415 1307 3 Saether, Mr. Simon Sivertsen male 38.5 0 0 SOTON/O.Q. 3101262 7.2500 NaN S
416 1308 3 Ware, Mr. Frederick male NaN 0 0 359309 8.0500 NaN S
417 1309 3 Peter, Master. Michael J male NaN 1 1 2668 22.3583 NaN C

418 rows × 11 columns

调用df的describe方法可以查看基本的统计信息：

PassengerId Pclass Age SibSp Parch Fare
count 418.000000 418.000000 332.000000 418.000000 418.000000 417.000000
mean 1100.500000 2.265550 30.272590 0.447368 0.392344 35.627188
std 120.810458 0.841838 14.181209 0.896760 0.981429 55.907576
min 892.000000 1.000000 0.170000 0.000000 0.000000 0.000000
25% 996.250000 1.000000 21.000000 0.000000 0.000000 7.895800
50% 1100.500000 3.000000 27.000000 0.000000 0.000000 14.454200
75% 1204.750000 3.000000 39.000000 1.000000 0.000000 31.500000
max 1309.000000 3.000000 76.000000 8.000000 9.000000 512.329200

如果要想查看乘客登录的港口，可以这样选择： 

df['Embarked'][:10]


0    Q

1    S

2    Q

3    S

4    S

5    S

6    Q

7    S

8    C

9    S

Name: Embarked, dtype: object

使用value_counts 可以对其进行统计： 

embark_counts=df['Embarked'].value_counts()

embark_counts[:10]


S    270

C    102

Q     46

Name: Embarked, dtype: int64

从结果可以看出，从S港口登录的乘客有270个，从C港口登录的乘客有102个，从Q港口登录的乘客有46个。

同样的，我们可以统计一下age信息： 

age_counts=df['Age'].value_counts()

age_counts.head(10)

前10位的年龄如下： 

24.0    17

21.0    17

22.0    16

30.0    15

18.0    13

27.0    12

26.0    12

25.0    11

23.0    11

29.0    10

Name: Age, dtype: int64

计算一下年龄的平均数： 

df['Age'].mean()


30.272590361445783

实际上有些数据是没有年龄的，我们可以使用平均数对其填充： 

clean_age1 = df['Age'].fillna(df['Age'].mean())

clean_age1.value_counts()

可以看出平均数是30.27，个数是86。 

30.27259    86

24.00000    17

21.00000    17

22.00000    16

30.00000    15

18.00000    13

26.00000    12

27.00000    12

25.00000    11

23.00000    11

            ..

36.50000     1

40.50000     1

11.50000     1

34.00000     1

15.00000     1

7.00000      1

60.50000     1

26.50000     1

76.00000     1

34.50000     1

Name: Age, Length: 80, dtype: int64

使用平均数来作为年龄可能不是一个好主意，还有一种办法就是丢弃平均数： 

clean_age2=df['Age'].dropna()

clean_age2

age_counts = clean_age2.value_counts()

ageset=age_counts.head(10)

ageset


24.0    17

21.0    17

22.0    16

30.0    15

18.0    13

27.0    12

26.0    12

25.0    11

23.0    11

29.0    10

Name: Age, dtype: int64

图形化表示和矩阵转换

图形化对于数据分析非常有帮助，我们对于上面得出的前10名的age使用柱状图来表示： 

import seaborn as sns

sns.barplot(x=ageset.index, y=ageset.values)

接下来我们来做一个复杂的矩阵变换，我们先来过滤掉age和sex都为空的数据： 

cframe=df[df.Age.notnull() & df.Sex.notnull()]

cframe
PassengerId Pclass Name Sex Age SibSp Parch Ticket Fare Cabin Embarked
0 892 3 Kelly, Mr. James male 34.5 0 0 330911 7.8292 NaN Q
1 893 3 Wilkes, Mrs. James (Ellen Needs) female 47.0 1 0 363272 7.0000 NaN S
2 894 2 Myles, Mr. Thomas Francis male 62.0 0 0 240276 9.6875 NaN Q
3 895 3 Wirz, Mr. Albert male 27.0 0 0 315154 8.6625 NaN S
4 896 3 Hirvonen, Mrs. Alexander (Helga E Lindqvist) female 22.0 1 1 3101298 12.2875 NaN S
5 897 3 Svensson, Mr. Johan Cervin male 14.0 0 0 7538 9.2250 NaN S
6 898 3 Connolly, Miss. Kate female 30.0 0 0 330972 7.6292 NaN Q
7 899 2 Caldwell, Mr. Albert Francis male 26.0 1 1 248738 29.0000 NaN S
8 900 3 Abrahim, Mrs. Joseph (Sophie Halaut Easu) female 18.0 0 0 2657 7.2292 NaN C
9 901 3 Davies, Mr. John Samuel male 21.0 2 0 A/4 48871 24.1500 NaN S
... ... ... ... ... ... ... ... ... ... ... ...
403 1295 1 Carrau, Mr. Jose Pedro male 17.0 0 0 113059 47.1000 NaN S
404 1296 1 Frauenthal, Mr. Isaac Gerald male 43.0 1 0 17765 27.7208 D40 C
405 1297 2 Nourney, Mr. Alfred (Baron von Drachstedt")" male 20.0 0 0 SC/PARIS 2166 13.8625 D38 C
406 1298 2 Ware, Mr. William Jeffery male 23.0 1 0 28666 10.5000 NaN S
407 1299 1 Widener, Mr. George Dunton male 50.0 1 1 113503 211.5000 C80 C
409 1301 3 Peacock, Miss. Treasteall female 3.0 1 1 SOTON/O.Q. 3101315 13.7750 NaN S
411 1303 1 Minahan, Mrs. William Edward (Lillian E Thorpe) female 37.0 1 0 19928 90.0000 C78 Q
412 1304 3 Henriksson, Miss. Jenny Lovisa female 28.0 0 0 347086 7.7750 NaN S
414 1306 1 Oliva y Ocana, Dona. Fermina female 39.0 0 0 PC 17758 108.9000 C105 C
415 1307 3 Saether, Mr. Simon Sivertsen male 38.5 0 0 SOTON/O.Q. 3101262 7.2500 NaN S

332 rows × 11 columns

接下来使用groupby对age和sex进行分组： 

by_sex_age = cframe.groupby(['Age', 'Sex'])

by_sex_age.size()


Age    Sex

0.17   female    1

0.33   male      1

0.75   male      1

0.83   male      1

0.92   female    1

1.00   female    3

2.00   female    1

       male      1

3.00   female    1

5.00   male      1

                ..

60.00  female    3

60.50  male      1

61.00  male      2

62.00  male      1

63.00  female    1

       male      1

64.00  female    2

       male      1

67.00  male      1

76.00  female    1

Length: 115, dtype: int64

使用unstack将Sex的列数据变成行：

Sex female male
Age
0.17 1.0 0.0
0.33 0.0 1.0
0.75 0.0 1.0
0.83 0.0 1.0
0.92 1.0 0.0
1.00 3.0 0.0
2.00 1.0 1.0
3.00 1.0 0.0
5.00 0.0 1.0
6.00 0.0 3.0
... ... ...
58.00 1.0 0.0
59.00 1.0 0.0
60.00 3.0 0.0
60.50 0.0 1.0
61.00 0.0 2.0
62.00 0.0 1.0
63.00 1.0 1.0
64.00 2.0 1.0
67.00 0.0 1.0
76.00 1.0 0.0

79 rows × 2 columns

我们把同样age的人数加起来，然后使用argsort进行排序，得到排序过后的index： 

indexer = agg_counts.sum(1).argsort()

indexer.tail(10)


Age

58.0    37

59.0    31

60.0    29

60.5    32

61.0    34

62.0    22

63.0    38

64.0    27

67.0    26

76.0    30

dtype: int64

从agg_counts中取出最后的10个，也就是最大的10个： 

count_subset = agg_counts.take(indexer.tail(10))

count_subset=count_subset.tail(10)

count_subset
Sex female male
Age
29.0 5.0 5.0
25.0 1.0 10.0
23.0 5.0 6.0
26.0 4.0 8.0
27.0 4.0 8.0
18.0 7.0 6.0
30.0 6.0 9.0
22.0 10.0 6.0
21.0 3.0 14.0
24.0 5.0 12.0

上面的操作可以简化为下面的代码： 

agg_counts.sum(1).nlargest(10)


Age

21.0    17.0

24.0    17.0

22.0    16.0

30.0    15.0

18.0    13.0

26.0    12.0

27.0    12.0

23.0    11.0

25.0    11.0

29.0    10.0

dtype: float64

将count_subset 进行stack操作，方便后面的画图： 

stack_subset = count_subset.stack()

stack_subset


Age   Sex

29.0  female     5.0

      male       5.0

25.0  female     1.0

      male      10.0

23.0  female     5.0

      male       6.0

26.0  female     4.0

      male       8.0

27.0  female     4.0

      male       8.0

18.0  female     7.0

      male       6.0

30.0  female     6.0

      male       9.0

22.0  female    10.0

      male       6.0

21.0  female     3.0

      male      14.0

24.0  female     5.0

      male      12.0

dtype: float64


stack_subset.name = 'total'

stack_subset = stack_subset.reset_index()

stack_subset
Age Sex total
0 29.0 female 5.0
1 29.0 male 5.0
2 25.0 female 1.0
3 25.0 male 10.0
4 23.0 female 5.0
5 23.0 male 6.0
6 26.0 female 4.0
7 26.0 male 8.0
8 27.0 female 4.0
9 27.0 male 8.0
10 18.0 female 7.0
11 18.0 male 6.0
12 30.0 female 6.0
13 30.0 male 9.0
14 22.0 female 10.0
15 22.0 male 6.0
16 21.0 female 3.0
17 21.0 male 14.0
18 24.0 female 5.0
19 24.0 male 12.0

作图如下： 

sns.barplot(x='total', y='Age', hue='Sex',  data=stack_subset)

本文例子可以参考： https://github.com/ddean2009/learn-ai/

本文已收录于 http://www.flydean.com/01-pandas-titanic/

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