CODEWITHSUNDEEP
pythonlistlist-comprehension
Pythonuser
Pythonuser

Reputation: 213

concatenate 2d list with list comprehension instead of a for loop

Hi I have a 2d list that has 3 elements I have concatenated some of the elements using the following code

    list1 = [(1,"hello",3),(1,"excelent",4),(2,"marvelous",3)]
    length = len(list1)
    text = ''
    for irow in range(length):
            number      = list1[irow][0]
            listText    = list1[irow][1]
            ids         = list1[irow][2]
            text += "<tag id = "+ str(ids)+">"+str(listText)+"<\\tag>\r\n"
    
    print(text)

and this produces the following output

<tag id = 3>hello<\tag> 
<tag id = 4>excelent<\tag> 
<tag id =3>marvelous<\tag>

and this is correct, my question is there a way to do this using list comprehension, or is there a more pythonic way of achieving this same outcome.

Upvotes: 0

Views: 85

Answers (4)

alani
alani

Reputation: 13069

You could reduce the whole thing to a one-liner, but I suggest that a reasonable compromise is probably still to use a for loop over your list, but in the for loop target you can unpack the sublists directly into the relevant variables. In any case there is no need for looping over index rather than the actual contents of list1. Using an f-string (in recent Python versions) will also help tidy things up.

list1 = [(1,"hello",3),(1,"excelent",4),(2,"marvelous",3)]

text = ''
for number, listText, ids in list1:
    text += f'<tag id = {ids}>{listText}<\\tag>\r\n'

print(text)

You could also consider using the conventional dummy variable _ in place of number here, because you are not actually using the value:

for _, listText, ids in list1:

Upvotes: 1

DirtyBit
DirtyBit

Reputation: 16772

Using list-comprehension:

ee = [(1,"hello",3),(1,"excelent",4),(2,"marvelous",3)]
  
print(["<tag id = "+ str(x[2])+">"+str(x[1])+"<\tag>" for x in ee])

OUTPUT:

['<tag id = 3>hello<\tag>', '<tag id = 4>excelent<\tag>', '<tag id = 3>marvelous<\tag>']

Edit:

If you want to have the double quotes in the tags text:

print(["<tag id = " + str(x[2])+" >" + str('"' + x[1] + '"') + "<\tag>" for x in ee])

OUTPUT:

['<tag id = 3 >"hello"<\tag>', '<tag id = 4 >"excelent"<\tag>', '<tag id = 3 >"marvelous"<\tag>']

Upvotes: 1

user14127951
user14127951

Reputation:

iterate lambda function and use map()

list1 = [(1, "hello", 3), (1, "excelent", 4), (2, "marvelous", 3)]
text = map(lambda x: f'<tag id = {x[2]}>{x[1]}<\\tag>', list1)
print('\r\n'.join(list(text)))

Upvotes: 0

AKX
AKX

Reputation: 168913

Using f-strings and unpacking the tuple elements in the list comprehension makes this neatly readable:

list1 = [
    (1, "hello", 3),
    (1, "excelent", 4),
    (2, "marvelous", 3),
]
texts = [
    f'<tag id="{ids}">{text}<\\tag>'  # TODO: handle HTML quoting?
    for (number, text, ids) in list1
]
text = "\r\n".join(texts)

Upvotes: 0

Related Questions