## 2018年2月24日 星期六

### [ Python 常見問題 ] unfold function in python

Source From Here
Question
I have started practicing functional programming in python recently. Lets say I define a function that gets an array of digits and concatenates it:
>>> def fromDigits(digits):
... return reduce(lambda x, y: 10 * x + y, digits, 0)
...
>>> fromDigits([1, 2, 3])
123

Now I want to implement the reverse function:
1. def toDigits(num):
2.    return unfold(lambda m,digits: (m/10,digits+[m % 10]) if m>0 else None,  num,  [])
But I couldn't find a definition of unfold in the python functools or anywhere in the standard library.

How-To
unfold is not a python function ... here is a recursive solution:
1. def to_digits(x):
2.     if not x: return []
3.     return to_digits(x//10) + [x%10]
4.
5. to_digits(12345)

### [Linux 文章收集] Linux / Unix: Check Last Time User Logged In On The System

Source From  Here   Question   I am a new Unix system admin. How do I find ouw who has recently use the Linux or Unix-like server?  Which te...