How to concatenate all lists (each lists are made my for loop)

Question

I'm crawling webpage by python BeautifulSoup, requests, Pandas library, trying to collect information of many items in many pages by for loop. But when I run these code, I could only get lists separated from each others, so I want to edit this code to concatenated by one list.

Well, actually my problem is not 'concatenating list' itself. I know it already, but the problem is, In case of the fuction gives a result that 'list' one by one, how can I edit the code to make a result that gives 'one list' that concatenated all together, Or return [[list],[list],[list]] form that I can easily concatenate all together.

Windows, Jupyter Notebook, Python

def a(content):
    ptag_title=content.find("p",{"class":"title"})
    ptag_price=content.find("p",{"class":"price-sale"})
    return {"title":ptag_title.text, "price":ptag_price.text}

def get_pd_page(url):
    result = requests.get(url)
    bs_obj = bs4.BeautifulSoup(result.content,"html.parser")
    pbl=bs_obj.find("div",{"class":"product-box-list"})
    contents = pbl.findAll("div",{"class":"content"})
    pdinfo_list = [get_pdinfo(content ) for content in contents]
    return pdinfo_listn = 10

urls = [None] * n
fix_str = "https://www.abcdef.com"

for page_num in range(0,n):
    page_str = fix_str + str(page_num+1)
    urls[page_num] = page_str
    page_products = get_pd_page(urls[page_num])
    print(page_products)

result for each pages are separated lists.

[{'title':a, 'price'=b},{'title':c, 'price'=d}] [{'title':d, 'price'=e},{'title':f, 'price'=g]

I want to make this whole one list.

[{'title':a, 'price'=b},{'title':c, 'price'=d},{'title':d, 'price'=e},{'title':f, 'price'=g]

Or, at least, by lists of lists

[[{'title':a, 'price'=b},{'title':c, 'price'=d}],[{'title':d, 'price'=e},{'title':f, 'price'=g]]

The OP also asks how to contacentate list of lists, which the duplicate doesn't answer! — Devesh Kumar Singh, May 09 '19 at 07:05
You can use + operator or a list comprehension to concatenate lists @JaguarBlack — Devesh Kumar Singh, May 09 '19 at 23:48

score 1 · Accepted Answer · answered May 09 '19 at 07:02

Use the + operator to concatenate any number of lists

In [19]: li1 = [1,2,3]                                                                                                         

In [20]: li2 = [4,5,6]                                                                                                         

In [21]: li1+li2                                                                                                               
Out[21]: [1, 2, 3, 4, 5, 6]

Or use a list comprehension to concatenate the sublists inside a list of lists, also called flattening a list

In [23]: li = [[1,2,3],[4,5,6],[7,8,9]]  

In [30]: flat_list = [item for sublist in li for item in sublist]                                                              

In [31]: flat_list                                                                                                             
Out[31]: [1, 2, 3, 4, 5, 6, 7, 8, 9]

These are simpler examples then what you are trying to achieve, but a similar approach will solve the problem you have at end!

Great, glad to help @JaguarBlack :) Please consider marking the answer as accepted by clicking the tick next to the answer if it helped you :) Also consider reading https://stackoverflow.com/help/someone-answers — Devesh Kumar Singh, May 14 '19 at 09:59

How to concatenate all lists (each lists are made my for loop)

1 Answers1