Python常见的pandas用法demo示例

2024-02-26 02:56:29

本文实例总结了Python常见的pandas用法。分享给大家供大家参考，具体如下：

import numpy as np
import pandas as pd

s = pd.Series([1,3,6, np.nan, 44, 1]) #定义一个序列。 序列就是一列内容，每一行有一个index值
print(s)
print(s.index)

0     1.0
1     3.0
2     6.0
3     NaN
4    44.0
5     1.0
dtype: float64
RangeIndex(start=0, stop=6, step=1)

dates = pd.date_range('20180101', periods=6)
print(dates)

DatetimeIndex(['2018-01-01', '2018-01-02', '2018-01-03', '2018-01-04',
'2018-01-05', '2018-01-06'],
dtype='datetime64[ns]', freq='D')

df1 = pd.DataFrame(np.arange(12).reshape(3,4)) #定义DataFrame，可以看作一个有index和colunms的矩阵
print(df)

0 1   2   3
0 0 1   2   3
1 4 5   6   7
2 8 9 10 11

df2 = pd.DataFrame(np.random.randn(6,4), index=dates, columns=['a', 'b', 'c', 'd']) #np.random.randn(6,4)生成6行4列矩阵
print(df)

a b c d
2018-01-01 0.300675 1.769383 1.244406 -1.058294
2018-01-02 0.832666 2.216755 0.178716 -0.156828
2018-01-03 1.314190 -0.866199 0.836150 1.001026
2018-01-04 -1.671724 1.147406 -0.148676 -0.272555
2018-01-05 1.146664 2.022861 -1.833995 -0.627568
2018-01-06 -0.192242 1.517676 0.756707 0.058869

df = pd.DataFrame({'A':1.0,
          'B':pd.Timestamp('20180101'),
          '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'}) #按照给出的逐列定义df

print(df)
print(df.dtypes)

A          B    C D      E    F
0 1.0 2018-01-01 1.0 3   test foo
1 1.0 2018-01-01 1.0 3 train foo
2 1.0 2018-01-01 1.0 3   test foo
3 1.0 2018-01-01 1.0 3 train foo
A           float64
B    datetime64[ns]
C           float32
D             int32
E          category
F            object
dtype: object

#df的行、列、值
print(df.index)
print(df.columns)
print(df.values)

Int64Index([0, 1, 2, 3], dtype='int64')
Index(['A', 'B', 'C', 'D', 'E', 'F'], dtype='object')
[[1.0 Timestamp('2018-01-01 00:00:00') 1.0 3 'test' 'foo']
[1.0 Timestamp('2018-01-01 00:00:00') 1.0 3 'train' 'foo']
[1.0 Timestamp('2018-01-01 00:00:00') 1.0 3 'test' 'foo']
[1.0 Timestamp('2018-01-01 00:00:00') 1.0 3 'train' 'foo']]

print(df.describe()) #统计
print(df.T) #转置

A    C    D
count 4.0 4.0 4.0
mean   1.0 1.0 3.0
std    0.0 0.0 0.0
min    1.0 1.0 3.0
25%    1.0 1.0 3.0
50%    1.0 1.0 3.0
75%    1.0 1.0 3.0
max    1.0 1.0 3.0
                     0                    1                    2 \
A                    1                    1                    1
B 2018-01-01 00:00:00 2018-01-01 00:00:00 2018-01-01 00:00:00
C                    1                    1                    1
D                    3                    3                    3
E                 test                train                 test
F                  foo                  foo                  foo
                     3
A                    1
B 2018-01-01 00:00:00
C                    1
D                    3
E                train
F                  foo

#df排序
print(df.sort_index(axis=1, ascending=False)) #根据索引值对各行进行排序（相当于重新排列各列的位置）
print(df.sort_values(by='E')) #根据内容值对各列进行排序

F      E D    C          B    A
0 foo   test 3 1.0 2018-01-01 1.0
1 foo train 3 1.0 2018-01-01 1.0
2 foo   test 3 1.0 2018-01-01 1.0
3 foo train 3 1.0 2018-01-01 1.0
     A          B    C D      E    F
0 1.0 2018-01-01 1.0 3   test foo
2 1.0 2018-01-01 1.0 3   test foo
1 1.0 2018-01-01 1.0 3 train foo
3 1.0 2018-01-01 1.0 3 train foo

indexes = pd.date_range('20180101', periods=6)
df3 = pd.DataFrame(np.arange(24).reshape(6, 4), index=indexes, columns=['A', 'B', 'C', 'D'])
print(df3)
print()
#选择column
print(df3['A'])
print()
print(df3.A)

A   B   C   D
2018-01-01   0   1   2   3
2018-01-02   4   5   6   7
2018-01-03   8   9 10 11
2018-01-04 12 13 14 15
2018-01-05 16 17 18 19
2018-01-06 20 21 22 23
2018-01-01     0
2018-01-02     4
2018-01-03     8
2018-01-04    12
2018-01-05    16
2018-01-06    20
Freq: D, Name: A, dtype: int32
2018-01-01     0
2018-01-02     4
2018-01-03     8
2018-01-04    12
2018-01-05    16
2018-01-06    20
Freq: D, Name: A, dtype: int32
            A B   C   D
2018-01-01 0 1   2   3
2018-01-02 4 5   6   7
2018-01-03 8 9 10 11

#选择行， 类似limit语句
print(df3[0:0])
print()
print(df3[0:3])
print()
print(df3['20180103':'20180105'])

Empty DataFrame
Columns: [A, B, C, D]
Index: []
            A B   C   D
2018-01-01 0 1   2   3
2018-01-02 4 5   6   7
2018-01-03 8 9 10 11
             A   B   C   D
2018-01-03   8   9 10 11
2018-01-04 12 13 14 15
2018-01-05 16 17 18 19

print(df3.loc['20180102']) #返回指定行构成的序列

A    4
B    5
C    6
D    7
Name: 2018-01-02 00:00:00, dtype: int32

print(df3.loc['20180103', ['A','C']]) #列筛选
print()
print(df3.loc['20180103':'20180105', ['A','C']]) #子df，类似select A, C from df limit ...
print()
print(df3.loc[:, ['A', 'B']])

A     8
C    10
Name: 2018-01-03 00:00:00, dtype: int32
             A   C
2018-01-03   8 10
2018-01-04 12 14
2018-01-05 16 18
             A   B
2018-01-01   0   1
2018-01-02   4   5
2018-01-03   8   9
2018-01-04 12 13
2018-01-05 16 17
2018-01-06 20 21

print(df3);print()
print(df3.iloc[1]);print()
print(df3.iloc[1,1]);print()
print(df3.iloc[:,1]);print()
print(df3.iloc[0:3,1:3]);print()
print(df3.iloc[[1,3,5],[0,2]]) #行可以不连续，limit做不到

A   B   C   D
2018-01-01   0   1   2   3
2018-01-02   4   5   6   7
2018-01-03   8   9 10 11
2018-01-04 12 13 14 15
2018-01-05 16 17 18 19
2018-01-06 20 21 22 23
A    4
B    5
C    6
D    7
Name: 2018-01-02 00:00:00, dtype: int32
5
2018-01-01     1
2018-01-02     5
2018-01-03     9
2018-01-04    13
2018-01-05    17
2018-01-06    21
Freq: D, Name: B, dtype: int32
            B   C
2018-01-01 1   2
2018-01-02 5   6
2018-01-03 9 10
             A   C
2018-01-02   4   6
2018-01-04 12 14
2018-01-06 20 22

# print(df3.ix[:3, ['A', 'C']])\
print(df3);print()
print(df3[df3.A >= 8]) #根据值进行条件过滤，类似where A >= 8条件语句

A   B   C   D
2018-01-01   0   1   2   3
2018-01-02   4   5   6   7
2018-01-03   8   9 10 11
2018-01-04 12 13 14 15
2018-01-05 16 17 18 19
2018-01-06 20 21 22 23
             A   B   C   D
2018-01-03   8   9 10 11
2018-01-04 12 13 14 15
2018-01-05 16 17 18 19
2018-01-06 20 21 22 23

indexes1 = pd.date_range('20180101', periods=6)
df4 = pd.DataFrame(np.arange(24).reshape(6, 4), index=indexes1, columns=['A', 'B', 'C', 'D'])
print(df4);print()
#给某个元素赋值
df4.A[1] = 1111
df4.B['20180103'] = 2222
df4.iloc[3, 2] = 3333
df4.loc['20180105', 'D'] = 4444
print(df4);print()
#范围赋值
df4.B[df4.A < 10] = -1
print(df4);print()
df4[df4.A < 10] = 0
print(df4);print()

A   B   C   D
2018-01-01   0   1   2   3
2018-01-02   4   5   6   7
2018-01-03   8   9 10 11
2018-01-04 12 13 14 15
2018-01-05 16 17 18 19
2018-01-06 20 21 22 23
               A     B     C     D
2018-01-01     0     1     2     3
2018-01-02 1111     5     6     7
2018-01-03     8 2222    10    11
2018-01-04    12    13 3333    15
2018-01-05    16    17    18 4444
2018-01-06    20    21    22    23
               A   B     C     D
2018-01-01     0 -1     2     3
2018-01-02 1111   5     6     7
2018-01-03     8 -1    10    11
2018-01-04    12 13 3333    15
2018-01-05    16 17    18 4444
2018-01-06    20 21    22    23
               A   B     C     D
2018-01-01     0   0     0     0
2018-01-02 1111   5     6     7
2018-01-03     0   0     0     0
2018-01-04    12 13 3333    15
2018-01-05    16 17    18 4444
2018-01-06    20 21    22    23

indexes1 = pd.date_range('20180101', periods=6)
df4 = pd.DataFrame(np.arange(24).reshape(6, 4), index=indexes1, columns=['A', 'B', 'C', 'D'])
print(df4);print()
#添加一列
df4['E'] = np.NaN
print(df4);print()
#由于index没对齐，原df没有的行默认为NaN，类型为float64,多出的行丢弃
df4['F'] = pd.Series([1,2,3,4,5,6], index=pd.date_range('20180102', periods=6))
print(df4);print()
print(df4.dtypes)

A   B   C   D
2018-01-01   0   1   2   3
2018-01-02   4   5   6   7
2018-01-03   8   9 10 11
2018-01-04 12 13 14 15
2018-01-05 16 17 18 19
2018-01-06 20 21 22 23
             A   B   C   D   E
2018-01-01   0   1   2   3 NaN
2018-01-02   4   5   6   7 NaN
2018-01-03   8   9 10 11 NaN
2018-01-04 12 13 14 15 NaN
2018-01-05 16 17 18 19 NaN
2018-01-06 20 21 22 23 NaN
             A   B   C   D   E    F
2018-01-01   0   1   2   3 NaN NaN
2018-01-02   4   5   6   7 NaN 1.0
2018-01-03   8   9 10 11 NaN 2.0
2018-01-04 12 13 14 15 NaN 3.0
2018-01-05 16 17 18 19 NaN 4.0
2018-01-06 20 21 22 23 NaN 5.0
A      int32
B      int32
C      int32
D      int32
E    float64
F    float64
dtype: object

df_t = pd.DataFrame(np.arange(24).reshape(6, 4), index=[1,2,3,4,5,6], columns=['A', 'B', 'C', 'D'])
df_t.iloc[0, 1] = np.NaN
df_t.iloc[1, 2] = np.NaN
df = df_t.copy()
print(df);print()
print(df.dropna(axis=0, how='any'));print()
df = df_t.copy()
print(df.dropna(axis=1, how='any'));print()
df = df_t.copy()
df.C = np.NaN
print(df);print()
print(df.dropna(axis=1, how='all'));print()

A     B     C   D
1   0   NaN   2.0   3
2   4   5.0   NaN   7
3   8   9.0 10.0 11
4 12 13.0 14.0 15
5 16 17.0 18.0 19
6 20 21.0 22.0 23
    A     B     C   D
3   8   9.0 10.0 11
4 12 13.0 14.0 15
5 16 17.0 18.0 19
6 20 21.0 22.0 23
    A   D
1   0   3
2   4   7
3   8 11
4 12 15
5 16 19
6 20 23
    A     B   C   D
1   0   NaN NaN   3
2   4   5.0 NaN   7
3   8   9.0 NaN 11
4 12 13.0 NaN 15
5 16 17.0 NaN 19
6 20 21.0 NaN 23
    A     B   D
1   0   NaN   3
2   4   5.0   7
3   8   9.0 11
4 12 13.0 15
5 16 17.0 19
6 20 21.0 23

df = df_t.copy()
print(df);print()
print(df.isna());print()
print(df.isnull().any());print() #isnull是isna别名，功能一样
print(df.isnull().any(axis=1));print()
print(np.any(df.isna() == True));print()
print(df.fillna(value=0)) #将NaN赋值

A     B     C   D
1   0   NaN   2.0   3
2   4   5.0   NaN   7
3   8   9.0 10.0 11
4 12 13.0 14.0 15
5 16 17.0 18.0 19
6 20 21.0 22.0 23
       A      B      C      D
1 False   True False False
2 False False   True False
3 False False False False
4 False False False False
5 False False False False
6 False False False False
A    False
B     True
C     True
D    False
dtype: bool
1     True
2     True
3    False
4    False
5    False
6    False
dtype: bool
True
    A     B     C   D
1   0   0.0   2.0   3
2   4   5.0   0.0   7
3   8   9.0 10.0 11
4 12 13.0 14.0 15
5 16 17.0 18.0 19
6 20 21.0 22.0 23

data = pd.read_csv('D:/pythonwp/test/student.csv')
print(data)
data.to_pickle('D:/pythonwp/test/student.pickle')

id     name age gender
0   1       牛帅   23    Male
1   2      gyb   89    Male
2   3      xxs   27    Male
3   4      hey   24 Female
4   5    奥莱利赫本   66 Female
5   6 Jackson   61    Male
6   7       牛帅   23    Male

df0 = pd.DataFrame(np.ones((3, 4)) * 0, columns=['A', 'B', 'C', 'D'])
df1 = pd.DataFrame(np.ones((3, 4)) * 1, columns=['A', 'B', 'C', 'D'])
df2 = pd.DataFrame(np.ones((3, 4)) * 2, columns=['A', 'B', 'C', 'D'])
print(df0); print()
print(df1); print()
print(df2); print()
res = pd.concat([df0, df1, df2], axis = 0)
print(res); print()
res = pd.concat([df0, df1, df2], axis = 0, ignore_index=True)
print(res)

A    B    C    D
0 0.0 0.0 0.0 0.0
1 0.0 0.0 0.0 0.0
2 0.0 0.0 0.0 0.0
     A    B    C    D
0 1.0 1.0 1.0 1.0
1 1.0 1.0 1.0 1.0
2 1.0 1.0 1.0 1.0
     A    B    C    D
0 2.0 2.0 2.0 2.0
1 2.0 2.0 2.0 2.0
2 2.0 2.0 2.0 2.0
     A    B    C    D
0 0.0 0.0 0.0 0.0
1 0.0 0.0 0.0 0.0
2 0.0 0.0 0.0 0.0
0 1.0 1.0 1.0 1.0
1 1.0 1.0 1.0 1.0
2 1.0 1.0 1.0 1.0
0 2.0 2.0 2.0 2.0
1 2.0 2.0 2.0 2.0
2 2.0 2.0 2.0 2.0
     A    B    C    D
0 0.0 0.0 0.0 0.0
1 0.0 0.0 0.0 0.0
2 0.0 0.0 0.0 0.0
3 1.0 1.0 1.0 1.0
4 1.0 1.0 1.0 1.0
5 1.0 1.0 1.0 1.0
6 2.0 2.0 2.0 2.0
7 2.0 2.0 2.0 2.0
8 2.0 2.0 2.0 2.0

df0 = pd.DataFrame(np.ones((3, 4)) * 0, columns=['A', 'B', 'C', 'D'])
df1 = pd.DataFrame(np.ones((3, 4)) * 1, columns=['E', 'F', 'C', 'D'])
res = pd.concat([df0, df1], ignore_index=True)
print(res);print()
res = pd.concat([df0, df1], join='outer', ignore_index=True)
print(res);print()
res = pd.concat([df0, df1], join='inner',ignore_index=True)
print(res);print()

A    B    C    D    E    F
0 0.0 0.0 0.0 0.0 NaN NaN
1 0.0 0.0 0.0 0.0 NaN NaN
2 0.0 0.0 0.0 0.0 NaN NaN
3 NaN NaN 1.0 1.0 1.0 1.0
4 NaN NaN 1.0 1.0 1.0 1.0
5 NaN NaN 1.0 1.0 1.0 1.0
     A    B    C    D    E    F
0 0.0 0.0 0.0 0.0 NaN NaN
1 0.0 0.0 0.0 0.0 NaN NaN
2 0.0 0.0 0.0 0.0 NaN NaN
3 NaN NaN 1.0 1.0 1.0 1.0
4 NaN NaN 1.0 1.0 1.0 1.0
5 NaN NaN 1.0 1.0 1.0 1.0
     C    D
0 0.0 0.0
1 0.0 0.0
2 0.0 0.0
3 1.0 1.0
4 1.0 1.0
5 1.0 1.0

#横向合并
df0 = pd.DataFrame(np.ones((3, 4)) * 0, index=['1', '2', '3'], columns=['A', 'B', 'C', 'D'])
df1 = pd.DataFrame(np.ones((3, 4)) * 1, index=['2', '3', '4'], columns=['A', 'B', 'C', 'D'])
print(df0);print()
print(df1);print()
res = pd.concat([df0, df1], axis=1)
print(res);print()
res = pd.concat([df0, df1], axis=1, join='inner', ignore_index=True)
print(res);print()
res = pd.concat([df0, df1], axis=1, join_axes=[df0.index])
print(res);print()

A    B    C    D
1 0.0 0.0 0.0 0.0
2 0.0 0.0 0.0 0.0
3 0.0 0.0 0.0 0.0
     A    B    C    D
2 1.0 1.0 1.0 1.0
3 1.0 1.0 1.0 1.0
4 1.0 1.0 1.0 1.0
     A    B    C    D    A    B    C    D
1 0.0 0.0 0.0 0.0 NaN NaN NaN NaN
2 0.0 0.0 0.0 0.0 1.0 1.0 1.0 1.0
3 0.0 0.0 0.0 0.0 1.0 1.0 1.0 1.0
4 NaN NaN NaN NaN 1.0 1.0 1.0 1.0
     0    1    2    3    4    5    6    7
2 0.0 0.0 0.0 0.0 1.0 1.0 1.0 1.0
3 0.0 0.0 0.0 0.0 1.0 1.0 1.0 1.0
     A    B    C    D    A    B    C    D
1 0.0 0.0 0.0 0.0 NaN NaN NaN NaN
2 0.0 0.0 0.0 0.0 1.0 1.0 1.0 1.0
3 0.0 0.0 0.0 0.0 1.0 1.0 1.0 1.0

df0 = pd.DataFrame(np.ones((3, 4)) * 0, index=['1', '2', '3'], columns=['A', 'B', 'C', 'D'])
df1 = pd.DataFrame(np.ones((3, 4)) * 1, index=['2', '3', '4'], columns=['A', 'B', 'C', 'D'])
print(df0);print()
print(df1);print()
res = df0.append([df1, df1], ignore_index=False)
print(res);print()
s = pd.Series([1,2,3,4], index=['A','B','C','E'])
print(df0.append(s, ignore_index=True))

A    B    C    D
1 0.0 0.0 0.0 0.0
2 0.0 0.0 0.0 0.0
3 0.0 0.0 0.0 0.0
     A    B    C    D
2 1.0 1.0 1.0 1.0
3 1.0 1.0 1.0 1.0
4 1.0 1.0 1.0 1.0
     A    B    C    D
1 0.0 0.0 0.0 0.0
2 0.0 0.0 0.0 0.0
3 0.0 0.0 0.0 0.0
2 1.0 1.0 1.0 1.0
3 1.0 1.0 1.0 1.0
4 1.0 1.0 1.0 1.0
2 1.0 1.0 1.0 1.0
3 1.0 1.0 1.0 1.0
4 1.0 1.0 1.0 1.0
     A    B    C    D    E
0 0.0 0.0 0.0 0.0 NaN
1 0.0 0.0 0.0 0.0 NaN
2 0.0 0.0 0.0 0.0 NaN
3 1.0 2.0 3.0 NaN 4.0

df1 = pd.DataFrame({'key':['K0', 'K1', 'K2'],
          'A':['A0', 'A1', 'A2'],
          'B':['B0', 'B1', 'B2']})
df2 = pd.DataFrame({'key':['K3', 'K1', 'K2'],
          'C':['C3', 'C1', 'C2'],
          'D':['D3', 'D1', 'D2']})
print(df1); print()
print(df2); print()
res = pd.merge(df1, df2, on='key')
print(res); print()
res = pd.merge(df1, df2, on='key', how='outer')
print(res); print()
res = pd.merge(df1, df2, on='key', how='left')
print(res); print()
res = pd.merge(df1, df2, on='key', how='right')
print(res); print()

A   B key
0 A0 B0 K0
1 A1 B1 K1
2 A2 B2 K2
    C   D key
0 C3 D3 K3
1 C1 D1 K1
2 C2 D2 K2
    A   B key   C   D
0 A1 B1 K1 C1 D1
1 A2 B2 K2 C2 D2
     A    B key    C    D
0   A0   B0 K0 NaN NaN
1   A1   B1 K1   C1   D1
2   A2   B2 K2   C2   D2
3 NaN NaN K3   C3   D3
    A   B key    C    D
0 A0 B0 K0 NaN NaN
1 A1 B1 K1   C1   D1
2 A2 B2 K2   C2   D2
     A    B key   C   D
0   A1   B1 K1 C1 D1
1   A2   B2 K2 C2 D2
2 NaN NaN K3 C3 D3

df1 = pd.DataFrame({'key1':['K0', 'K0', 'K1'],
          'key2':['K0', 'K1', 'K1'],
          'A':['A0', 'A1', 'A2'],
          'B':['B0', 'B1', 'B2']})
df2 = pd.DataFrame({'key1':['K0', 'K0', 'K1', 'K2'],
          'key2':['K0', 'K0', 'K1', 'K2'],
          'C':['C3', 'C1', 'C2', 'C4'],
          'D':['D3', 'D1', 'D2', 'D4']})
print(df1); print()
print(df2); print()
res = pd.merge(df1, df2, on=['key1','key2'])
print(res); print()
res = pd.merge(df1, df2, on=['key1','key2'], how='outer', indicator='indi')
print(res); print()

A   B key1 key2
0 A0 B0   K0   K0
1 A1 B1   K0   K1
2 A2 B2   K1   K1
    C   D key1 key2
0 C3 D3   K0   K0
1 C1 D1   K0   K0
2 C2 D2   K1   K1
3 C4 D4   K2   K2
    A   B key1 key2   C   D
0 A0 B0   K0   K0 C3 D3
1 A0 B0   K0   K0 C1 D1
2 A2 B2   K1   K1 C2 D2
     A    B key1 key2    C    D        indi
0   A0   B0   K0   K0   C3   D3        both
1   A0   B0   K0   K0   C1   D1        both
2   A1   B1   K0   K1 NaN NaN   left_only
3   A2   B2   K1   K1   C2   D2        both
4 NaN NaN   K2   K2   C4   D4 right_only

#以上是根据值合并。下面根据index合并
df1 = pd.DataFrame({'A':['A0', 'A1', 'A2'],
          'B':['B0', 'B1', 'B2']},
          index=['index0', 'index1', 'index2'])
df2 = pd.DataFrame({'A':['C3', 'C1', 'C2'],
          'D':['D3', 'D1', 'D2']},
          index=['index3', 'index1', 'index2'])
print(df1); print()
print(df2); print()
res = pd.merge(df1, df2, left_index=True, right_index=True)
print(res); print()
res = pd.merge(df1, df2, left_index=True, right_index=True, how='outer', suffixes=['_b', '_g'])
print(res); print()

A   B
index0 A0 B0
index1 A1 B1
index2 A2 B2
         A   D
index3 C3 D3
index1 C1 D1
index2 C2 D2
       A_x   B A_y   D
index1 A1 B1 C1 D1
index2 A2 B2 C2 D2
        A_b    B A_g    D
index0   A0   B0 NaN NaN
index1   A1   B1   C1   D1
index2   A2   B2   C2   D2
index3 NaN NaN   C3   D3

res = df1.join(df2, how='outer', lsuffix='_left', rsuffix='_right') #不用on默认用索引合并
print(res);print()
res = df1.join(df2, on='B', how='outer', lsuffix='_left', rsuffix='_right') #用on指定df1的某列和df2的索引合并
print(res);print()

A_left    B A_right    D
index0     A0   B0     NaN NaN
index1     A1   B1      C1   D1
index2     A2   B2      C2   D2
index3    NaN NaN      C3   D3
       A_left       B A_right    D
index0     A0      B0     NaN NaN
index1     A1      B1     NaN NaN
index2     A2      B2     NaN NaN
index2    NaN index3      C3   D3
index2    NaN index1      C1   D1
index2    NaN index2      C2   D2

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt #画图模块
s = pd.Series(np.random.randn(1000), index=np.arange(1000))
s = s.cumsum()
#须在命令行执行， jupyter会报错
#s.plot()
#plt.show()
df = pd.DataFrame(np.random.randn(1000, 3), columns=['A', 'B', 'C'])
df = df.cumsum()
print(df.head()); print() #head默认显示前5行
#须在命令行执行， jupyter会报错
#s.plot()
#plt.show()
#须在命令行执行， jupyter会报错
#'bar', 'hist', 'box', 'kde', 'area', 'scatter', 'hexbin', 'pie'...
#class_B = df.plot.scatter(x='A', y='B', color='DarkBlue', label='Class B') #画图，scatter<散点图>
#df.plot.scatter(x='A', y='C', color='DarkRed', label='Class C', class_B=class_B)
#plt.show()

A B C
0 -0.399363 -1.004210 0.641141
1 -1.970009 -0.608482 -0.758504
2 -3.081640 -0.617352 -1.143872
3 -2.174627 -1.383785 -1.011411
4 -1.415515 -1.892226 -2.511739

更多关于Python相关内容感兴趣的读者可查看本站专题：《Python操作Excel表格技巧总结》、《Python文件与目录操作技巧汇总》、《Python文本文件操作技巧汇总》、《Python数据结构与算法教程》、《Python函数使用技巧总结》、《Python字符串操作技巧汇总》及《Python入门与进阶经典教程》

希望本文所述对大家Python程序设计有所帮助。

Python科学计算之Pandas详解

起步 Pandas最初被作为金融数据分析工具而开发出来,因此 pandas 为时间序列分析提供了很好的支持. Pandas 的名称来自于面板数据(panel data)和python数据分析 (data analysis) .panel data是经济学中关于多维数据集的一个术语,在Pandas中也提供了panel的数据类型. 在我看来,对于 Numpy 以及 Matplotlib ,Pandas可以帮助创建一个非常牢固的用于数据挖掘与分析的基础.而Scipy当然是另一个主要的也十分出色的科学计
Python pandas常用函数详解

本文研究的主要是pandas常用函数,具体介绍如下. 1 import语句 import pandas as pd import numpy as np import matplotlib.pyplot as plt import datetime import re 2 文件读取 df = pd.read_csv(path='file.csv') 参数:header=None 用默认列名,0,1,2,3... names=['A', 'B', 'C'...] 自定义列名 index_col='
Windows下Python使用Pandas模块操作Excel文件的教程

安装Python环境 ANACONDA是一个Python的发行版本,包含了400多个Python最常用的库,其中就包括了数据分析中需要经常使用到的Numpy和Pandas等.更重要的是,不论在哪个平台上,都可以一键安装,自动配置好环境,不需要用户任何的额外操作,非常方便.因此,安装Python环境就只需要到ANACONDA网站上下载安装文件,双击安装即可. ANACONDA官方下载地址:https://www.continuum.io/downloads 安装完成之后,使用windows + r
在Python中利用Pandas库处理大数据的简单介绍

在数据分析领域,最热门的莫过于Python和R语言,此前有一篇文章<别老扯什么Hadoop了,你的数据根本不够大>指出:只有在超过5TB数据量的规模下,Hadoop才是一个合理的技术选择.这次拿到近亿条日志数据,千万级数据已经是关系型数据库的查询分析瓶颈,之前使用过Hadoop对大量文本进行分类,这次决定采用Python来处理数据: 硬件环境 CPU:3.5 GHz Intel Core i7 内存:32 GB HDDR 3 1600 MHz 硬
python之pandas用法大全

一.生成数据表 1.首先导入pandas库,一般都会用到numpy库,所以我们先导入备用: import numpy as np import pandas as pd 2.导入CSV或者xlsx文件: df = pd.DataFrame(pd.read_csv('name.csv',header=1)) df = pd.DataFrame(pd.read_excel('name.xlsx')) 3.用pandas创建数据表: df = pd.DataFrame({"id":[1001
python中pandas.DataFrame的简单操作方法（创建、索引、增添与删除）

前言最近在网上搜了许多关于pandas.DataFrame的操作说明,都是一些基础的操作,但是这些操作组合起来还是比较费时间去正确操作DataFrame,花了我挺长时间去调整BUG的.我在这里做一些总结,方便你我他.感兴趣的朋友们一起来看看吧. 一.创建DataFrame的简单操作: 1.根据字典创造: In [1]: import pandas as pd In [3]: aa={'one':[1,2,3],'two':[2,3,4],'three':[3,4,5]} In [4]: bb=
python中pandas.DataFrame排除特定行方法示例

前言大家在使用Python进行数据分析时,经常要使用到的一个数据结构就是pandas的DataFrame,关于python中pandas.DataFrame的基本操作,大家可以查看这篇文章. pandas.DataFrame排除特定行如果我们想要像Excel的筛选那样,只要其中的一行或某几行,可以使用isin()方法,将需要的行的值以列表方式传入,还可以传入字典,指定列进行筛选. 但是如果我们只想要所有内容中不包含特定行的内容,却并没有一个isnotin()方法.我今天的工作就遇到了这样的需
python pandas dataframe 按列或者按行合并的方法

concat 与其说是连接,更准确的说是拼接.就是把两个表直接合在一起.于是有一个突出的问题,是横向拼接还是纵向拼接,所以concat 函数的关键参数是axis . 函数的具体参数是: concat(objs,axis=0,join='outer',join_axes=None,ignore_index=False,keys=None,levels=None,names=None,verigy_integrity=False) objs 是需要拼接的对象集合,一般为列表或者字典 axis=0 是
Python遍历pandas数据方法总结

前言 Pandas是python的一个数据分析包,提供了大量的快速便捷处理数据的函数和方法.其中Pandas定义了Series 和 DataFrame两种数据类型,这使数据操作变得更简单.Series 是一种一维的数据结构,类似于将列表数据值与索引值相结合.DataFrame 是一种二维的数据结构,接近于电子表格或者mysql数据库的形式. 在数据分析中不可避免的涉及到对数据的遍历查询和处理,比如我们需要将dataframe两列数据两两相除,并将结果存储于一个新的列表中.本文通过该例程介绍对pa
python pandas 如何替换某列的一个值

摘要:本文主要是讲解怎么样替换某一列的一个值. 应用场景: 假如我们有以下的数据集: 我们想把里面不是pre的字符串全部换成Nonpre,我们要怎么做呢? 做法很简单. df['col2']=df['col1'] df.loc[df['col1'] !=' pre','col2']=Nonpre 以上这篇python pandas 如何替换某列的一个值就是小编分享给大家的全部内容了,希望能给大家一个参考,也希望大家多多支持我们.

Python常见的pandas用法demo示例

相关推荐

随机推荐