参考：[https://zhuanlan.zhihu.com/p/108418193](https://zhuanlan.zhihu.com/p/108418193)





![在这里插入图片描述](/static/img/images/00360.png)

什么时候需要定义类 而不是函数？

python安装opencv：





> pip install opencv-python

提取视频帧 视频转图片：
```python
import os
mp4file = 'input.mp4'
savefile = "./output"
if not os.path.exists(savefile):
    os.mkdir(savefile)
import cv2
cap = cv2.VideoCapture(mp4file)
fourcc = cv2.VideoWriter_fourcc(*'XVID')
fps = cap.get(cv2.CAP_PROP_FPS)
size = (int(cap.get(cv2.CAP_PROP_FRAME_WIDTH)), int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT)))
print(fps)
print(size)
i = 0
while (cap.isOpened()):
    i = i + 1
    ret, frame = cap.read()
    if ret == True:
        cv2.imwrite(savefile + '/' + str(i) + '.jpg', frame)
        if cv2.waitKey(1) & 0xFF == ord('q'):
            break
    else:
        break
print(i)
cap.release()
cv2.destroyAllWindows()
```

图片转视频：

```python
import os
mp4file = 'out.mp4'
savefile = "./output"
if not os.path.exists(savefile):
    os.mkdir(savefile)
import cv2
fourcc = cv2.VideoWriter_fourcc(*'XVID')
fps = 30
size =(720, 1280)
videoWriter = cv2.VideoWriter(mp4file, fourcc, fps, size)  # 最后一个是保存图片的尺寸
for i in range(1, 1402):
    frame = cv2.imread(savefile + '/' + str(i) + '.jpg')
    videoWriter.write(frame)
videoWriter.release()
```


合成，一定得注意尺寸的大小。

```python
# coding=utf-8
import os
import cv2
from PIL import Image
def makevideo(path, fps):
    """ 将图片合成视频. path: 视频路径，fps: 帧率 """
    fourcc = cv2.VideoWriter_fourcc(*"mp4v")
    path1 = r'D:\yifei111\PycharmProjects\python_test\jigan_res4'
    im = Image.open(r'D:\yifei111\PycharmProjects\python_test\jigan1\251.jpg')
    print(im.size)
    vw = cv2.VideoWriter(path, fourcc, fps, im.size)
    for i in os.listdir(path1):
        frame = cv2.imread(path1 + '\\' + i)
        frame = frame[200:649, :]
        frame = cv2.resize(frame, im.size)
        vw.write(frame)
if __name__ == '__main__':
    video_path = r'D:\yifei111\PycharmProjects\python_test\DST_test_new4.mp4'
    makevideo(video_path, 30)  # 图片转视频
```

python opencv 提取视频帧 视频转图片 图片转视频

借助pd.date_range快速实现





## 生成 Timestamp对象 列表

生成一系列Timestamp对象，Timestamp对象是对python datetime再封装得到的，一般情况直接用起来就好了。
```python
import pandas as pd
a = list(pd.date_range(start='2021-06-21 00:00:00', end='2021-06-22 00:00:00', freq='H'))
print(a)
```

得到：

[Timestamp('2021-06-21 00:00:00', freq='H'), Timestamp('2021-06-21 01:00:00', freq='H'), Timestamp('2021-06-21 02:00:00', freq='H'), Timestamp('2021-06-21 03:00:00', freq='H'), Timestamp('2021-06-21 04:00:00', freq='H'), Timestamp('2021-06-21 05:00:00', freq='H'), Timestamp('2021-06-21 06:00:00', freq='H'), Timestamp('2021-06-21 07:00:00', freq='H'), Timestamp('2021-06-21 08:00:00', freq='H'), Timestamp('2021-06-21 09:00:00', freq='H'), Timestamp('2021-06-21 10:00:00', freq='H'), Timestamp('2021-06-21 11:00:00', freq='H'), Timestamp('2021-06-21 12:00:00', freq='H'), Timestamp('2021-06-21 13:00:00', freq='H'), Timestamp('2021-06-21 14:00:00', freq='H'), Timestamp('2021-06-21 15:00:00', freq='H'), Timestamp('2021-06-21 16:00:00', freq='H'), Timestamp('2021-06-21 17:00:00', freq='H'), Timestamp('2021-06-21 18:00:00', freq='H'), Timestamp('2021-06-21 19:00:00', freq='H'), Timestamp('2021-06-21 20:00:00', freq='H'), Timestamp('2021-06-21 21:00:00', freq='H'), Timestamp('2021-06-21 22:00:00', freq='H'), Timestamp('2021-06-21 23:00:00', freq='H'), Timestamp('2021-06-22 00:00:00', freq='H')]

## 生成 str对象 列表

```python
import pandas as pd
a = list(pd.date_range(start='2021-06-21 00:00:00', end='2021-06-22 00:00:00', freq='H'))
a=list(map(str,a))
print(a)
```

得到：

['2021-06-21 00:00:00', '2021-06-21 01:00:00', '2021-06-21 02:00:00', '2021-06-21 03:00:00', '2021-06-21 04:00:00', '2021-06-21 05:00:00', '2021-06-21 06:00:00', '2021-06-21 07:00:00', '2021-06-21 08:00:00', '2021-06-21 09:00:00', '2021-06-21 10:00:00', '2021-06-21 11:00:00', '2021-06-21 12:00:00', '2021-06-21 13:00:00', '2021-06-21 14:00:00', '2021-06-21 15:00:00', '2021-06-21 16:00:00', '2021-06-21 17:00:00', '2021-06-21 18:00:00', '2021-06-21 19:00:00', '2021-06-21 20:00:00', '2021-06-21 21:00:00', '2021-06-21 22:00:00', '2021-06-21 23:00:00', '2021-06-22 00:00:00']

## 生成 python datetime对象 列表

```python
import pandas as pd
a = list(pd.date_range(start='2021-06-21 00:00:00', end='2021-06-22 00:00:00', freq='H'))
a=list(map(lambda x:x.to_pydatetime(),a))
print(a)
```

得到：

```python
[datetime.datetime(2021, 6, 21, 0, 0), datetime.datetime(2021, 6, 21, 1, 0), datetime.datetime(2021, 6, 21, 2, 0), datetime.datetime(2021, 6, 21, 3, 0), datetime.datetime(2021, 6, 21, 4, 0), datetime.datetime(2021, 6, 21, 5, 0), datetime.datetime(2021, 6, 21, 6, 0), datetime.datetime(2021, 6, 21, 7, 0), datetime.datetime(2021, 6, 21, 8, 0), datetime.datetime(2021, 6, 21, 9, 0), datetime.datetime(2021, 6, 21, 10, 0), datetime.datetime(2021, 6, 21, 11, 0), datetime.datetime(2021, 6, 21, 12, 0), datetime.datetime(2021, 6, 21, 13, 0), datetime.datetime(2021, 6, 21, 14, 0), datetime.datetime(2021, 6, 21, 15, 0), datetime.datetime(2021, 6, 21, 16, 0), datetime.datetime(2021, 6, 21, 17, 0), datetime.datetime(2021, 6, 21, 18, 0), datetime.datetime(2021, 6, 21, 19, 0), datetime.datetime(2021, 6, 21, 20, 0), datetime.datetime(2021, 6, 21, 21, 0), datetime.datetime(2021, 6, 21, 22, 0), datetime.datetime(2021, 6, 21, 23, 0), datetime.datetime(2021, 6, 22, 0, 0)]
```

# 转换

 pd.Timestamp 转 datetime.datetime  ：
```python
pd.Timestamp("2021-06-06").to_pydatetime()
```

datetime.datetime  转 pd.Timestamp：

```python
pd.to_datetime(datetime.datetime.now())
```

python 生成一段日期列表 pd.date_range Timestamp 转 datetime datetime 转 Timestamp

（1）本质核心是多进程里执行os.system("wget filename")，开17个进程的进程池意味着同时在下载17个文件。





（2）将指令全部放列表needgfsfile里面。

```python
import datetime
import multiprocessing
import os
def downloadgfs(filename):
    os.system(filename)
start_hour = 12
yesterday = (datetime.datetime.now() - datetime.timedelta(days=1)).replace(hour=start_hour, microsecond=0)
ymdstr = f"{str(yesterday.year).zfill(4)}{str(yesterday.month).zfill(2)}{str(yesterday.day).zfill(2)}{str(start_hour).zfill(2)}"
if not os.path.exists(ymdstr):
    os.mkdir(ymdstr)
needgfsfile = [
    f"wget ftp://ftpprd.ncep.noaa.gov/pub/data/nccf/com/gfs/prod/gfs.{ymdstr[:-2]}/{ymdstr[-2:]}/atmos/gfs.t{ymdstr[-2:]}z.pgrb2.0p50.f{str(i * 24).zfill(3)} -P {ymdstr}/"
    for i in range(17)]
p = multiprocessing.Pool(processes=17)  # 进to程池
_ = [p.apply_async(func=downloadgfs, args=(i,)) for i in needgfsfile]
p.close()
p.join()
```

python wget 并行下载多个文件 同时下载多个文件 ftp文件 多进程

## 1 加解释器后加路径





![在这里插入图片描述](/static/img/images/00435.png)

## 2 配置

![在这里插入图片描述](/static/img/images/00436.png)

这样点一下后切到用户目录作为Root path

![在这里插入图片描述](/static/img/images/00437.png)

手动修改这里：

![在这里插入图片描述](/static/img/images/00438.png)

## 3 第一次需要手动上传

![在这里插入图片描述](/static/img/images/00439.png)