# Python Project
## 调试
```python
exit() # 执行到此处中止
```
## [Numpy](https://pypi.org/project/numpy/) - 矩阵计算
### 安装
{% embed url="" %}
### 使用
```python
import numpy as np
array = np.array([[1,2,3],
[2,3,4]])
print(array)
print('number of dim:', array.ndim) # 输出矩阵的维数
print('shape:', array.shape) # 输出矩阵的行列数
print('size:', array.size) # 输出矩阵的元素数
```
```python
import numpy as np
a = np.array([10,20,30,40])
b = np.arange(4)
print(a,b)
# 输出结果:
# [10 20 30 40] [0 1 2 3]
```
```python
import numpy as np
a = np.array([10,20,30,40])
b = np.arange(4)
print(a,b)
c = a+b
print(c)
# 输出结果:
# [10 20 30 40] [0 1 2 3]
# [10 21 32 43]
```
```python
import numpy as np
a = np.array([10,20,30,40])
b = np.arange(4)
print(a,b)
c = a-b
print(c)
# 输出结果:
# [10 20 30 40] [0 1 2 3]
# [10 19 28 37]
```
```python
import numpy as np
a = np.array([10,20,30,40])
b = np.arange(4)
c = b**2
print(c)
# 输出结果:
# [0 1 4 9]
```
```python
import numpy as np
a = np.array([10,20,30,40])
b = np.arange(4)
c = 10*np.sin(a)
print(c)
# 输出结果:
# [-5.44021111 9.12945251 -9.88031624 7.4511316]
```
```python
import numpy as np
a = np.array([10,20,30,40])
b = np.arange(4)
print(b)
print(b<3)
# 输出结果:
# [0 1 2 3]
# [True True True False]
```
```python
import numpy as np
a = np.array([10,20,30,40])
b = np.arange(4)
print(b)
print(b==3)
# 输出结果:
# [0 1 2 3]
# [False False False True]
```
```python
import numpy as np
a = np.array([10,20,30,40])
b = np.arange(4)
print(b)
print(b==3)
# 输出结果:
# [0 1 2 3]
# [False False False True]
```
```python
import numpy as np
a = np.array([[1,1],
[0,1]])
b = np.arange(4).reshape((2,2))
print(a)
print(b)
c = a*b
c_dot = np.dot(a,b)
print(c)
print(c_dot)
# 输出结果:
# [[1 1]
# [0 1]]
# [[0 1]
# [2 3]]
# [[0 1]
# [0 3]]
# [[2 4]
# [2 3]]
```
{% embed url="" %}
## [Pandas](https://pypi.org/project/pandas/) - 数据分析
### 安装
{% embed url="" %}
### 使用 - 读取数据
```python
import pandas as pd
pd.read_csv('/path') #读取csv文件
pd.read_excel('/path') #读取excel表格
pd.read_table('/path') #读取txt文本
```
```python
import pandas as pd
pd.read_csv('/path', encoding='gbk')
# encoding='gbk' : 防止出现中文乱码
```
```python
import pandas as pd
DataName_data = pd.read_csv('/path', encoding='gbk') # 导入为DataName_data
print DataName_data # 打印DataName_data
```
```python
import pandas as pd
DataName_data = pd.read_csv('/path', encoding='gbk') # 导入为DataName_data
print DataName_data[['列名1']] # 打印DataName_data的某一列
print DataName_data[['列名1', '列名2']] # 打印DataName_data的某两列
```
```python
import pandas as pd
DataName_data = pd.read_csv('/path', encoding='gbk') # 导入为DataName_data
DataName_data[['新增列名1']] = '新增列值1' # 新增一列
print DataName_data # 打印DataName_data
```
### 使用 - 排序数据
```python
import pandas as pd
DataName_data = pd.read_csv('/path', encoding='gbk') # 导入为DataName_data
DataName_data.sort_values(by = ['列名1', '列名2'], inplace = True)
# 先按列名1排序，再按列名2排序
print DataName_data # 打印DataName_data
```
### 使用 - 截取数据
```python
import pandas as pd
DataName_data = pd.read_csv('/path', encoding='gbk') # 导入为DataName_data
DataName_data = DataName_data['交易日期'] > pd.to_datetime(20201231)
print DataName_data # 打印DataName_data
```
## [Openpyxl](https://pypi.org/project/openpyxl/) - 处理EXCEL
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