# Snippets python

### Obtenir un item aléatoire d'une liste

```
import random
random.choice['a','b','c']
```

### Hash md5 d'un fichier

```
def get_hash(name):
    readsize = 64 * 1024
    with open(name, 'rb') as f:
        data = f.read(readsize)
        f.seek(-readsize, os.SEEK_END)
        data += f.read(readsize)
    return hashlib.md5(data).hexdigest()
```

### Texte aléatoire

```
def randomtext(n):
    # stackoverflow.com/questions/2257441
    #   /random-string-generation-with-upper-case-letters-and-digits-in-python/23728630#23728630
    txt = ''.join(random.SystemRandom().choice(string.ascii_uppercase + string.digits) for _ in range(n))
    return txt
```

### which

```
def which(program):
    #https://stackoverflow.com/questions/377017/test-if-executable-exists-in-python/377028#377028
    def is_exe(fpath):
        return os.path.isfile(fpath) and os.access(fpath, os.X_OK)
    fpath, fname = os.path.split(program)
    if fpath:
        if is_exe(program):
            return program
    else:
        for path in os.environ["PATH"].split(os.pathsep):
            path = path.strip('"')
            exe_file = os.path.join(path, program)
            if is_exe(exe_file):
                return exe_file
    return None
```

### Capturer CTRL-C

```
x = 1
while True:
    try:
        print x
        time.sleep(.3)
        x += 1
    except KeyboardInterrupt:
        print "Bye"
        sys.exit(0)
```

### Vérifier que l'on est connecté à internet

```
def check_connectivity():
    """
    check if internet access
    #https://stackoverflow.com/questions/3764291/checking-network-connection
    """
    try:
        request.urlopen("http://www.openbsd.org", timeout=10)
        return True
    except Exception as e:
        print(e)
        return False
```

### Equivalent à tail -f

```
def tail(filename):
    if not os.path.isfile(filename) :
        return
    # Watch the file for changes
    stat = os.stat(filename)
    size = stat.st_size
    mtime = stat.st_mtime
    while True:
        time.sleep(0.5)
        stat = os.stat(filename)
        if mtime < stat.st_mtime:
            mtime = stat.st_mtime
            with open(filename, "rb") as f:
                f.seek(size)
                lines = f.readlines()
                ul = [ u.decode() for u in lines ]
                yield("".join(ul).strip())
            size = stat.st_size
```