codecademy 代码学习1

1. Write a function called censor that takes two strings, text and word, as input. It should return the text with the word you chose replaced with asterisks.
For example: censor("this hack is wack hack", "hack") 
should return  "this **** is wack ****"

Assume your input strings won't contain punctuation or upper case letters.

The number of asterisks you put should correspond to the number of letters in the censored word.

 code：

def censor(text,word):

   new_lst=[]

    for w in text.split():

       print (w)

        if w==word:

            new_lst.append('*'*len(word))

        else:

            new_lst.append(w)

    return(' '.join(new_lst))

2. Define a function called count that has two arguments called sequence and item. Return the number of times the item occurs in the list.

For example: count([1,2,1,1], 1) should return 3 (because 1 appears 3 times in the list).

code:

def count(sequence,item):

    count=0

    for i in sequence:

        if i==item:

            count=count+1

    return count

3. Define a function called purify that takes in a list of numbers, removes all odd numbers in the list, and returns the result.

For example, purify([1,2,3]) should return [2].

code:

def purify(nums):

    new_list=[]

    for i in nums:

        if i%2==0:

            new_list.append(i)

    return new_list

4.remove_duplicates    
Write a function  remove_duplicates  that takes in a list and removes elements of the list that are the same.
For example:  remove_duplicates([1,1,2,2])  
should return  [1,2] .

code:

import copy
def remove_duplicates(lis):
    new_list=copy.deepcopy(lis)
    res=[]
    for li in new_list:
        if li not in res:
            res.append(li)
    return res
remove_duplicates([4,5,5,4])

5.median let's write a function to find the median of a list.The median is the middle number in a sorted sequence of numbers.

code:

def median(ls):     new_ls=sorted(ls)     if len(ls)%2==1:         median=sorted(ls)[(len(ls)-1)/2]     else:         median=(new_ls[(len(ls)-2)/2]+new_ls[len(ls)/2])/2.0     return median median([4,5,5,4])