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pandas從入門到上樓

發(fā)布時間:2020-04-05 10:26:01 來源:網絡 閱讀:11010 作者:youerning 欄目:大數(shù)據(jù)

數(shù)據(jù)對象

pandas主要有兩種數(shù)據(jù)對象

  1. Series
  2. DataFrame

    注: 后面代碼使用pandas版本0.20.1,通過import pandas as pd引入

Series

Series是一種帶有索引的序列對象

創(chuàng)建方式

簡單創(chuàng)建如下

# 通過傳入一個序列給pd.Series初始化一個Series對象, 比如list
s1 = pd.Series(list("1234"))
print(s1)
0    1
1    2
2    3
3    4
dtype: object

DataFrame

類似與數(shù)據(jù)庫table有行列的數(shù)據(jù)對象

創(chuàng)建方式如下
# 通過傳入一個numpy的二維數(shù)組或者dict對象給pd.DataFrame初始化一個DataFrame對象

# 通過numpy二維數(shù)組
import numpy as np
df1 = pd.DataFrame(np.random.randn(6,4))
print(df1)
    0   1   2   3
0   -0.646340   -1.249943   0.393323    -1.561873
1   0.371630    0.069426    1.693097    0.907419
2   -0.328575   -0.256765   0.693798    -0.787343
3   1.875764    -0.416275   -1.028718   0.158259
4   1.644791    -1.321506   -0.337425   0.820689
5   0.006391    -1.447894   0.506203    0.977295

# 通過dict字典
df2 = pd.DataFrame({ 'A' : 1.,
                     'B' : pd.Timestamp('20130102'),
                     'C' : pd.Series(1,index=list(range(4)),dtype='float32'),
                     'D' : np.array([3] * 4,dtype='int32'),
                     'E' : pd.Categorical(["test","train","test","train"]),
                     'F' : 'foo' })
print(df2)

    A   B   C   D   E   F
0   1.0 2013-01-02  1.0 3   test    foo
1   1.0 2013-01-02  1.0 3   train   foo
2   1.0 2013-01-02  1.0 3   test    foo
3   1.0 2013-01-02  1.0 3   train   foo

索引

不管是Series對象還是DataFrame對象都有一個對對象相對應的索引, Series的索引類似于每個元素, DataFrame的索引對應著每一行

查看

在創(chuàng)建對象的時候,每個對象都會初始化一個起始值為0,自增的索引列表, DataFrame同理

# 打印對象的時候,第一列就是索引
print(s1)
0    1
1    2
2    3
3    4
dtype: object

# 或者只查看索引, DataFrame同理
print(s1.index)

增刪查改

這里的增刪查改主要基于DataFrame對象

為了有足夠數(shù)據(jù)用于展示,這里選擇tushare的數(shù)據(jù)

tushare安裝

pip install tushare

創(chuàng)建數(shù)據(jù)對象如下

import tushare as ts
df = ts.get_k_data("000001")

DataFrame 行列,axis 圖解

pandas從入門到上樓

pandas從入門到上樓

查詢

查看每列的數(shù)據(jù)類型

# 查看df數(shù)據(jù)類型
df.dtypes
date       object
open      float64
close     float64
high      float64
low       float64
volume    float64
code       object
dtype: object

查看指定指定數(shù)量的行

head函數(shù)默認查看前5行,tail函數(shù)默認查看后5行,可以傳遞指定的數(shù)值用于查看指定行數(shù)

查看前5行
df.head()
date    open    close   high    low volume  code
0   2015-12-23  9.927   9.935   10.174  9.871   1039018.0   000001
1   2015-12-24  9.919   9.823   9.998   9.744   640229.0    000001
2   2015-12-25  9.855   9.879   9.927   9.815   399845.0    000001
3   2015-12-28  9.895   9.537   9.919   9.537   822408.0    000001
4   2015-12-29  9.545   9.624   9.632   9.529   619802.0    000001
# 查看后5行
df.tail()
date    open    close   high    low volume  code
636 2018-08-01  9.42    9.15    9.50    9.11    814081.0    000001
637 2018-08-02  9.13    8.94    9.15    8.88    931401.0    000001
638 2018-08-03  8.93    8.91    9.10    8.91    476546.0    000001
639 2018-08-06  8.94    8.94    9.11    8.89    554010.0    000001
640 2018-08-07  8.96    9.17    9.17    8.88    690423.0    000001
# 查看前10行
df.head(10)
date    open    close   high    low volume  code
0   2015-12-23  9.927   9.935   10.174  9.871   1039018.0   000001
1   2015-12-24  9.919   9.823   9.998   9.744   640229.0    000001
2   2015-12-25  9.855   9.879   9.927   9.815   399845.0    000001
3   2015-12-28  9.895   9.537   9.919   9.537   822408.0    000001
4   2015-12-29  9.545   9.624   9.632   9.529   619802.0    000001
5   2015-12-30  9.624   9.632   9.640   9.513   532667.0    000001
6   2015-12-31  9.632   9.545   9.656   9.537   491258.0    000001
7   2016-01-04  9.553   8.995   9.577   8.940   563497.0    000001
8   2016-01-05  8.972   9.075   9.210   8.876   663269.0    000001
9   2016-01-06  9.091   9.179   9.202   9.067   515706.0    000001

查看某一行或多行,某一列或多列

# 查看第一行
df[0:1]
    date    open    close   high    low volume  code
0   2015-12-23  9.927   9.935   10.174  9.871   1039018.0   000001

# 查看 10到20行
df[10:21]
    date    open    close   high    low volume  code
10  2016-01-07  9.083   8.709   9.083   8.685   174761.0    000001
11  2016-01-08  8.924   8.852   8.987   8.677   747527.0    000001
12  2016-01-11  8.757   8.566   8.820   8.502   732013.0    000001
13  2016-01-12  8.621   8.605   8.685   8.470   561642.0    000001
14  2016-01-13  8.669   8.526   8.709   8.518   391709.0    000001
15  2016-01-14  8.430   8.574   8.597   8.343   666314.0    000001
16  2016-01-15  8.486   8.327   8.597   8.295   448202.0    000001
17  2016-01-18  8.231   8.287   8.406   8.199   421040.0    000001
18  2016-01-19  8.319   8.526   8.582   8.287   501109.0    000001
19  2016-01-20  8.518   8.390   8.597   8.311   603752.0    000001
20  2016-01-21  8.343   8.215   8.558   8.215   606145.0    000001

# 查看看Date列前5個數(shù)據(jù)
df["date"].head() # 或者df.date.head()
0    2015-12-23
1    2015-12-24
2    2015-12-25
3    2015-12-28
4    2015-12-29
Name: date, dtype: object

# 查看看Date列,code列, open列前5個數(shù)據(jù)
df[["date","code", "open"]].head()
    date    code    open
0   2015-12-23  000001  9.927
1   2015-12-24  000001  9.919
2   2015-12-25  000001  9.855
3   2015-12-28  000001  9.895
4   2015-12-29  000001  9.545

使用行列組合條件查詢

# 查看date, code列的第10行
df.loc[10, ["date", "code"]]

date    2016-01-07
code        000001
Name: 10, dtype: object

# 查看date, code列的第10行到20行
df.loc[10:20, ["date", "code"]]

    date    code
10  2016-01-07  000001
11  2016-01-08  000001
12  2016-01-11  000001
13  2016-01-12  000001
14  2016-01-13  000001
15  2016-01-14  000001
16  2016-01-15  000001
17  2016-01-18  000001
18  2016-01-19  000001
19  2016-01-20  000001
20  2016-01-21  000001

# 查看第一行,open列的數(shù)據(jù)
df.loc[0, "open"]
9.9269999999999996

通過==位置==查詢

值得注意的是上面的索引值就是特定的位置

# 查看第1行()
df.iloc[0]
date      2015-12-24
open           9.919
close          9.823
high           9.998
low            9.744
volume        640229
code          000001
Name: 0, dtype: object

# 查看最后一行
df.iloc[-1]
date      2018-08-08
open            9.16
close           9.12
high            9.16
low              9.1
volume         29985
code          000001
Name: 640, dtype: object

# 查看第一列,前5個數(shù)值
df.iloc[:,0].head()
0    2015-12-24
1    2015-12-25
2    2015-12-28
3    2015-12-29
4    2015-12-30
Name: date, dtype: object

# 查看前2到4行,第1,3列
df.iloc[2:4,[0,2]]

date    close
2   2015-12-28  9.537
3   2015-12-29  9.624

通過條件篩選

查看open列大于10的前5行
df[df.open > 10].head()

    date    open    close   high    low volume  code
378 2017-07-14  10.483  10.570  10.609  10.337  1722570.0   000001
379 2017-07-17  10.619  10.483  10.987  10.396  3273123.0   000001
380 2017-07-18  10.425  10.716  10.803  10.299  2349431.0   000001
381 2017-07-19  10.657  10.754  10.851  10.551  1933075.0   000001
382 2017-07-20  10.745  10.638  10.880  10.580  1537338.0   000001

# 查看open列大于10且open列小于10.6的前五行
df[(df.open > 10) & (df.open < 10.6)].head()

    date    open    close   high    low volume  code
378 2017-07-14  10.483  10.570  10.609  10.337  1722570.0   000001
380 2017-07-18  10.425  10.716  10.803  10.299  2349431.0   000001
387 2017-07-27  10.550  10.422  10.599  10.363  1194490.0   000001
388 2017-07-28  10.441  10.569  10.638  10.412  819195.0    000001
390 2017-08-01  10.471  10.865  10.904  10.432  2035709.0   000001

# 查看open列大于10或open列小于10.6的前五行
df[(df.open > 10) | (df.open < 10.6)].head()

    date    open    close   high    low volume  code
0   2015-12-24  9.919   9.823   9.998   9.744   640229.0    000001
1   2015-12-25  9.855   9.879   9.927   9.815   399845.0    000001
2   2015-12-28  9.895   9.537   9.919   9.537   822408.0    000001
3   2015-12-29  9.545   9.624   9.632   9.529   619802.0    000001
4   2015-12-30  9.624   9.632   9.640   9.513   532667.0    000001

增加

在前面已經簡單的說明Series, DataFrame的創(chuàng)建,這里說一些常用有用的創(chuàng)建方式

# 創(chuàng)建2018-08-08到2018-08-15的時間序列,默認時間間隔為Day
s2 = pd.date_range("20180808", periods=7)
print(s2)

DatetimeIndex(['2018-08-08', '2018-08-09', '2018-08-10', '2018-08-11',
               '2018-08-12', '2018-08-13', '2018-08-14'],
              dtype='datetime64[ns]', freq='D')

# 指定2018-08-08 00:00 到2018-08-09 00:00 時間間隔為小時
# freq參數(shù)可使用參數(shù), 參考: http://pandas.pydata.org/pandas-docs/stable/timeseries.html#offset-aliases
s3 = pd.date_range("20180808", "20180809", freq="H")
print(s2)

DatetimeIndex(['2018-08-08 00:00:00', '2018-08-08 01:00:00',
               '2018-08-08 02:00:00', '2018-08-08 03:00:00',
               '2018-08-08 04:00:00', '2018-08-08 05:00:00',
               '2018-08-08 06:00:00', '2018-08-08 07:00:00',
               '2018-08-08 08:00:00', '2018-08-08 09:00:00',
               '2018-08-08 10:00:00', '2018-08-08 11:00:00',
               '2018-08-08 12:00:00', '2018-08-08 13:00:00',
               '2018-08-08 14:00:00', '2018-08-08 15:00:00',
               '2018-08-08 16:00:00', '2018-08-08 17:00:00',
               '2018-08-08 18:00:00', '2018-08-08 19:00:00',
               '2018-08-08 20:00:00', '2018-08-08 21:00:00',
               '2018-08-08 22:00:00', '2018-08-08 23:00:00',
               '2018-08-09 00:00:00'],
              dtype='datetime64[ns]', freq='H')

# 通過已有序列創(chuàng)建時間序列
s4 = pd.to_datetime(df.date.head())
print(s4)

0   2015-12-24
1   2015-12-25
2   2015-12-28
3   2015-12-29
4   2015-12-30
Name: date, dtype: datetime64[ns]

修改

# 將df 的索引修改為date列的數(shù)據(jù),并且將類型轉換為datetime類型
df.index = pd.to_datetime(df.date)
df.head()

    date    open    close   high    low volume  code
date                            
2015-12-24  2015-12-24  9.919   9.823   9.998   9.744   640229.0    000001
2015-12-25  2015-12-25  9.855   9.879   9.927   9.815   399845.0    000001
2015-12-28  2015-12-28  9.895   9.537   9.919   9.537   822408.0    000001
2015-12-29  2015-12-29  9.545   9.624   9.632   9.529   619802.0    000001
2015-12-30  2015-12-30  9.624   9.632   9.640   9.513   532667.0    000001

# 修改列的字段
df.columns = ["Date", "Open","Close","High","Low","Volume","Code"]
print(df.head())

                  Date   Open  Close   High    Low    Volume    Code
date                                                                
2015-12-24  2015-12-24  9.919  9.823  9.998  9.744  640229.0  000001
2015-12-25  2015-12-25  9.855  9.879  9.927  9.815  399845.0  000001
2015-12-28  2015-12-28  9.895  9.537  9.919  9.537  822408.0  000001
2015-12-29  2015-12-29  9.545  9.624  9.632  9.529  619802.0  000001
2015-12-30  2015-12-30  9.624  9.632  9.640  9.513  532667.0  000001

# 將Open列每個數(shù)值加1, apply方法并不直接修改源數(shù)據(jù),所以需要將新值復制給df
df.Open = df.Open.apply(lambda x: x+1)
df.head()

    Date    Open    Close   High    Low Volume  Code
date                            
2015-12-24  2015-12-24  10.919  9.823   9.998   9.744   640229.0    000001
2015-12-25  2015-12-25  10.855  9.879   9.927   9.815   399845.0    000001
2015-12-28  2015-12-28  10.895  9.537   9.919   9.537   822408.0    000001
2015-12-29  2015-12-29  10.545  9.624   9.632   9.529   619802.0    000001
2015-12-30  2015-12-30  10.624  9.632   9.640   9.513   532667.0    000001

# 將Open,Close列都數(shù)值上加1,如果多列,apply接收的對象是整個列
df[["Open", "Close"]].head().apply(lambda x: x.apply(lambda x: x+1))

            Open    Close
date        
2015-12-24  11.919  10.823
2015-12-25  11.855  10.879
2015-12-28  11.895  10.537
2015-12-29  11.545  10.624
2015-12-30  11.624  10.632

刪除

通過drop方法drop指定的行或者列

注意: drop方法并不直接修改源數(shù)據(jù),如果需要使源dataframe對象被修改,需要傳入inplace=True

通過之前的axis圖解,知道行的值(或者說label)在axis=0,列的值(或者說label)在axis=1

# 刪除指定列,刪除Open列
df.drop("Open", axis=1).head() #或者df.drop(df.columns[1])

    Date    Close   High    Low Volume  Code
date                        
2015-12-24  2015-12-24  9.823   9.998   9.744   640229.0    000001
2015-12-25  2015-12-25  9.879   9.927   9.815   399845.0    000001
2015-12-28  2015-12-28  9.537   9.919   9.537   822408.0    000001
2015-12-29  2015-12-29  9.624   9.632   9.529   619802.0    000001
2015-12-30  2015-12-30  9.632   9.640   9.513   532667.0    000001

# 刪除第1,3列. 即Open,High列
df.drop(df.columns[[1,3]], axis=1).head() # 或df.drop(["Open", "High], axis=1).head()

        Date    Close   Low Volume  Code
date                    
2015-12-24  2015-12-24  9.823   9.744   640229.0    000001
2015-12-25  2015-12-25  9.879   9.815   399845.0    000001
2015-12-28  2015-12-28  9.537   9.537   822408.0    000001
2015-12-29  2015-12-29  9.624   9.529   619802.0    000001
2015-12-30  2015-12-30  9.632   9.513   532667.0    000001

pandas常用參數(shù)

數(shù)值顯示格式

當數(shù)值很大的時候pandas默認會使用科學計數(shù)法

# float數(shù)據(jù)類型以{:.4f}格式顯示,即顯示完整數(shù)據(jù)且保留后四位
pd.options.display.float_format = '{:.4f}'.format

常用函數(shù)

統(tǒng)計

# descibe方法會計算每列數(shù)據(jù)對象是數(shù)值的count, mean, std, min, max, 以及一定比率的值
df.describe()

        Open    Close   High    Low Volume
count   641.0000    641.0000    641.0000    641.0000    641.0000
mean    10.7862 9.7927  9.8942  9.6863  833968.6162
std 1.5962  1.6021  1.6620  1.5424  607731.6934
min 8.6580  7.6100  7.7770  7.4990  153901.0000
25% 9.7080  8.7180  8.7760  8.6500  418387.0000
50% 10.0770 9.0960  9.1450  8.9990  627656.0000
75% 11.8550 10.8350 10.9920 10.7270 1039297.0000
max 15.9090 14.8600 14.9980 14.4470 4262825.0000

# 單獨統(tǒng)計Open列的平均值
df.Open.mean()
10.786248049922001

# 查看居于95%的值, 默認線性擬合
df.Open.quantile(0.95)
14.187

# 查看Open列每個值出現(xiàn)的次數(shù)
df.Open.value_counts().head()

9.8050    12
9.8630    10
9.8440    10
9.8730    10
9.8830     8
Name: Open, dtype: int64

缺失值處理

刪除或者填充缺失值

# 刪除含有NaN的任意行
df.dropna(how='any')

# 刪除含有NaN的任意列
df.dropna(how='any', axis=1)

# 將NaN的值改為5
df.fillna(value=5)

排序

按行或者列排序, 默認也不修改源數(shù)據(jù)

# 按列排序
df.sort_index(axis=1).head()

    Close   Code    Date    High    Low Open    Volume
date                            
2015-12-24  9.8230  000001  2015-12-24  9.9980  9.7440  10.9190 640229.0000
2015-12-25  1.0000  000001  2015-12-25  1.0000  9.8150  10.8550 399845.0000
2015-12-28  1.0000  000001  2015-12-28  1.0000  9.5370  10.8950 822408.0000
2015-12-29  9.6240  000001  2015-12-29  9.6320  9.5290  10.5450 619802.0000
2015-12-30  9.6320  000001  2015-12-30  9.6400  9.5130  10.6240 532667.0000

# 按行排序,不遞增
df.sort_index(ascending=False).head()

        Date    Open    Close   High    Low Volume  Code
date                            
2018-08-08  2018-08-08  10.1600 9.1100  9.1600  9.0900  153901.0000 000001
2018-08-07  2018-08-07  9.9600  9.1700  9.1700  8.8800  690423.0000 000001
2018-08-06  2018-08-06  9.9400  8.9400  9.1100  8.8900  554010.0000 000001
2018-08-03  2018-08-03  9.9300  8.9100  9.1000  8.9100  476546.0000 000001
2018-08-02  2018-08-02  10.1300 8.9400  9.1500  8.8800  931401.0000 000001

安裝某一列的值排序

# 按照Open列的值從小到大排序
df.sort_values(by="Open")
        Date    Open    Close   High    Low Volume  Code
date                            
2016-03-01  2016-03-01  8.6580  7.7220  7.7770  7.6260  377910.0000 000001
2016-02-15  2016-02-15  8.6900  7.7930  7.8410  7.6820  278499.0000 000001
2016-01-29  2016-01-29  8.7540  7.9610  8.0240  7.7140  544435.0000 000001
2016-03-02  2016-03-02  8.7620  8.0400  8.0640  7.7380  676613.0000 000001
2016-02-26  2016-02-26  8.7770  7.7930  7.8250  7.6900  392154.0000 000001

合并

concat, 按照行方向或者列方向合并

# 分別取0到2行,2到4行,4到9行組成一個列表,通過concat方法按照axis=0,行方向合并, axis參數(shù)不指定,默認為0
split_rows = [df.iloc[0:2,:],df.iloc[2:4,:], df.iloc[4:9]]
pd.concat(split_rows)

    Date    Open    Close   High    Low Volume  Code
date                            
2015-12-24  2015-12-24  10.9190 9.8230  9.9980  9.7440  640229.0000 000001
2015-12-25  2015-12-25  10.8550 1.0000  1.0000  9.8150  399845.0000 000001
2015-12-28  2015-12-28  10.8950 1.0000  1.0000  9.5370  822408.0000 000001
2015-12-29  2015-12-29  10.5450 9.6240  9.6320  9.5290  619802.0000 000001
2015-12-30  2015-12-30  10.6240 9.6320  9.6400  9.5130  532667.0000 000001
2015-12-31  2015-12-31  10.6320 9.5450  9.6560  9.5370  491258.0000 000001
2016-01-04  2016-01-04  10.5530 8.9950  9.5770  8.9400  563497.0000 000001
2016-01-05  2016-01-05  9.9720  9.0750  9.2100  8.8760  663269.0000 000001
2016-01-06  2016-01-06  10.0910 9.1790  9.2020  9.0670  515706.0000 000001

# 分別取2到3列,3到5列,5列及以后列數(shù)組成一個列表,通過concat方法按照axis=1,列方向合并
split_columns = [df.iloc[:,1:2], df.iloc[:,2:4], df.iloc[:,4:]]
pd.concat(split_columns, axis=1).head()

    Open    Close   High    Low Volume  Code
date                        
2015-12-24  10.9190 9.8230  9.9980  9.7440  640229.0000 000001
2015-12-25  10.8550 1.0000  1.0000  9.8150  399845.0000 000001
2015-12-28  10.8950 1.0000  1.0000  9.5370  822408.0000 000001
2015-12-29  10.5450 9.6240  9.6320  9.5290  619802.0000 000001
2015-12-30  10.6240 9.6320  9.6400  9.5130  532667.0000 000001

追加行, 相應的還有insert, 插入插入到指定位置

# 將第一行追加到最后一行
df.append(df.iloc[0,:], ignore_index=True).tail()

Date    Open    Close   High    Low Volume  Code
637 2018-08-03  9.9300  8.9100  9.1000  8.9100  476546.0000 000001
638 2018-08-06  9.9400  8.9400  9.1100  8.8900  554010.0000 000001
639 2018-08-07  9.9600  9.1700  9.1700  8.8800  690423.0000 000001
640 2018-08-08  10.1600 9.1100  9.1600  9.0900  153901.0000 000001
641 2015-12-24  10.9190 9.8230  9.9980  9.7440  640229.0000 000001

對象復制

由于dataframe是引用對象,所以需要顯示調用copy方法用以復制整個dataframe對象

繪圖

pandas的繪圖是使用matplotlib,如果想要畫的更細致, 可以使用matplotplib,不過簡單的畫一些圖還是不錯的

因為上圖太麻煩,這里就不配圖了,可以在資源文件里面查看pandas-blog.ipynb文件或者自己敲一遍代碼。

# 這里使用notbook,為了直接在輸出中顯示,需要以下配置
%matplotlib inline
# 繪制Open,Low,Close.High的線性圖
df[["Open", "Low", "High", "Close"]].plot()

# 繪制面積圖
df[["Open", "Low", "High", "Close"]].plot(kind="area")

數(shù)據(jù)讀寫

讀寫常見文件格式,如csv,excel,json等, 甚至是讀取==系統(tǒng)的剪切板==.這個功能有時候很有用。直接將鼠標選中復制的內容讀取創(chuàng)建dataframe對象。

# 將df數(shù)據(jù)保存到當前工作目錄的stock.csv文件
df.to_csv("stock.csv")

# 查看stock.csv文件前5行
with open("stock.csv") as rf:
    print(rf.readlines()[:5])

['date,Date,Open,Close,High,Low,Volume,Code\n', '2015-12-24,2015-12-24,9.919,9.823,9.998,9.744,640229.0,000001\n', '2015-12-25,2015-12-25,9.855,9.879,9.927,9.815,399845.0,000001\n', '2015-12-28,2015-12-28,9.895,9.537,9.919,9.537,822408.0,000001\n', '2015-12-29,2015-12-29,9.545,9.624,9.632,9.529,619802.0,000001\n']

# 讀取stock.csv文件并將第一行作為index
df2 = pd.read_csv("stock.csv", index_col=0)
df2.head()

    Date    Open    Close   High    Low Volume  Code
date                            
2015-12-24  2015-12-24  9.9190  9.8230  9.9980  9.7440  640229.0000 1
2015-12-25  2015-12-25  9.8550  9.8790  9.9270  9.8150  399845.0000 1
2015-12-28  2015-12-28  9.8950  9.5370  9.9190  9.5370  822408.0000 1
2015-12-29  2015-12-29  9.5450  9.6240  9.6320  9.5290  619802.0000 1
2015-12-30  2015-12-30  9.6240  9.6320  9.6400  9.5130  532667.0000 1

# 讀取stock.csv文件并將第一行作為index,并且將000001作為str類型讀取, 不然會被解析成整數(shù)
df2 = pd.read_csv("stock.csv", index_col=0, dtype={"Code": str})
df2.head()

簡單實例

這里以處理web日志為例,也許不太實用 ,因為ELK處理這些綽綽有余,不過喜歡什么自己來也未嘗不可

分析access.log

日志文件: https://raw.githubusercontent.com/Apache-Labor/labor/master/labor-04/labor-04-example-access.log

日志格式及示例
# 日志格式
# 字段說明, 參考:https://ru.wikipedia.org/wiki/Access.log
%h%l%u%t \“%r \”%> s%b \“%{Referer} i \”\“%{User-Agent} i \”

# 具體示例
75.249.65.145 US - [2015-09-02 10:42:51.003372] "GET /cms/tina-access-editor-for-download/ HTTP/1.1" 200 7113 "-" "Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)" www.example.com 124.165.3.7 443 redirect-handler - + "-" Vea2i8CoAwcAADevXAgAAAAB TLSv1.2 ECDHE-RSA-AES128-GCM-SHA256 701 12118 -% 88871 803 0 0 0 0
讀取并解析日志文件

解析日志文件

HOST = r'^(?P<host>.*?)'
SPACE = r'\s'
IDENTITY = r'\S+'
USER = r"\S+"
TIME = r'\[(?P<time>.*?)\]'
# REQUEST = r'\"(?P<request>.*?)\"'
REQUEST = r'\"(?P<method>.+?)\s(?P<path>.+?)\s(?P<http_protocol>.*?)\"'
STATUS = r'(?P<status>\d{3})'
SIZE = r'(?P<size>\S+)'
REFER = r"\S+"
USER_AGENT = r'\"(?P<user_agent>.*?)\"'

REGEX = HOST+SPACE+IDENTITY+SPACE+USER+SPACE+TIME+SPACE+REQUEST+SPACE+STATUS+SPACE+SIZE+SPACE+IDENTITY+USER_AGENT+SPACE
line = '79.81.243.171 - - [30/Mar/2009:20:58:31 +0200] "GET /exemples.php HTTP/1.1" 200 11481 "http://www.facades.fr/" "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 1.0.3705; .NET CLR 1.1.4322; Media Center PC 4.0; .NET CLR 2.0.50727)" "-"'
reg = re.compile(REGEX)
reg.match(line).groups()

將數(shù)據(jù)注入DataFrame對象

COLUMNS = ["Host", "Time", "Method", "Path", "Protocol", "status", "size", "User_Agent"]

field_lis = []
with open("access.log") as rf:
    for line in rf:
        # 由于一些記錄不能匹配,所以需要捕獲異常, 不能捕獲的數(shù)據(jù)格式如下
        # 80.32.156.105 - - [27/Mar/2009:13:39:51 +0100] "GET  HTTP/1.1" 400 - "-" "-" "-"
        # 由于重點不在寫正則表達式這里就略過了
        try:
            fields = reg.match(line).groups()
        except Exception as e:
            #print(e)
            #print(line)
            pass
        field_lis.append(fields)

log_df  = pd.DataFrame(field_lis)
# 修改列名
log_df.columns = COLUMNS

def parse_time(value):
    try:
        return pd.to_datetime(value)
    except Exception as e:
        print(e)
        print(value)

# 將Time列的值修改成pandas可解析的時間格式
log_df.Time = log_df.Time.apply(lambda x: x.replace(":", " ", 1))
log_df.Time = log_df.Time.apply(parse_time)

# 修改index, 將Time列作為index,并drop掉在Time列
log_df.index = pd.to_datetime(log_df.Time)
log_df.drop("Time", inplace=True)
log_df.head()

    Host    Time    Method  Path    Protocol    status  size    User_Agent
Time                                
2009-03-22 06:00:32 88.191.254.20   2009-03-22 06:00:32 GET /   HTTP/1.0    200 8674    "-
2009-03-22 06:06:20 66.249.66.231   2009-03-22 06:06:20 GET /popup.php?choix=-89    HTTP/1.1    200 1870    "Mozilla/5.0 (compatible; Googlebot/2.1; +htt...
2009-03-22 06:11:20 66.249.66.231   2009-03-22 06:11:20 GET /specialiste.php    HTTP/1.1    200 10743   "Mozilla/5.0 (compatible; Googlebot/2.1; +htt...
2009-03-22 06:40:06 83.198.250.175  2009-03-22 06:40:06 GET /   HTTP/1.1    200 8714    "Mozilla/4.0 (compatible; MSIE 7.0; Windows N...
2009-03-22 06:40:06 83.198.250.175  2009-03-22 06:40:06 GET /style.css  HTTP/1.1    200 1692    "Mozilla/4.0 (compatible; MSIE 7.0; Windows N...

查看數(shù)據(jù)類型

# 查看數(shù)據(jù)類型
log_df.dtypes

Host                  object
Time          datetime64[ns]
Method                object
Path                  object
Protocol              object
status                object
size                  object
User_Agent            object
dtype: object

由上可知, 除了Time字段是時間類型,其他都是object,但是Size, Status應該為數(shù)字

def parse_number(value):
    try:
        return pd.to_numeric(value)
    except Exception as e:
        pass
        return 0

# 將Size,Status字段值改為數(shù)值類型
log_df[["Status","Size"]] = log_df[["Status","Size"]].apply(lambda x: x.apply(parse_number))
log_df.dtypes

Host                  object
Time          datetime64[ns]
Method                object
Path                  object
Protocol              object
Status                 int64
Size                   int64
User_Agent            object
dtype: object

統(tǒng)計status數(shù)據(jù)

# 統(tǒng)計不同status值的次數(shù)
log_df.Status.value_counts()

200    5737
304    1540
404    1186
400     251
302      37
403       3
206       2
Name: Status, dtype: int64

繪制pie圖

log_df.Status.value_counts().plot(kind="pie", figsize=(10,8))

pandas從入門到上樓

查看日志文件時間跨度

log_df.index.max() - log_df.index.min()

Timedelta('15 days 11:12:03')

分別查看起始,終止時間

print(log_df.index.max())
print(log_df.index.min())

2009-04-06 17:12:35
2009-03-22 06:00:32

按照此方法還可以統(tǒng)計Method, User_Agent字段 ,不過User_Agent還需要額外清洗以下數(shù)據(jù)

統(tǒng)計top 10 IP地址

91.121.31.184     745
88.191.254.20     441
41.224.252.122    420
194.2.62.185      255
86.75.35.144      184
208.89.192.106    170
79.82.3.8         161
90.3.72.207       157
62.147.243.132    150
81.249.221.143    141
Name: Host, dtype: int64

繪制請求走勢圖

log_df2 = log_df.copy()
# 為每行加一個request字段,值為1
log_df2["Request"] = 1
# 每一小時統(tǒng)計一次request數(shù)量,并將NaN值替代為0,最后繪制線性圖,尺寸為16x9
log_df2.Request.resample("H").sum().fillna(0).plot(kind="line",figsize=(16,10))

pandas從入門到上樓

分別繪圖

分別對202,304,404狀態(tài)重新取樣,并放在一個列表里面
req_df_lis = [
log_df2[log_df2.Status == 200].Request.resample("H").sum().fillna(0),
log_df2[log_df2.Status == 304].Request.resample("H").sum().fillna(0),
log_df2[log_df2.Status == 404].Request.resample("H").sum().fillna(0)
]

# 將三個dataframe組合起來
req_df = pd.concat(req_df_lis,axis=1)
req_df.columns = ["200", "304", "404"]
# 繪圖
req_df.plot(figsize=(16,10))

pandas從入門到上樓

參考鏈接

https://pandas.pydata.org/pandas-docs/stable/index.html

源代碼等資源文件

https://github.com/youerning/blog/tree/master/pandas

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