I have a list1 like this,
list1 = [('my', '1.2.3', 2),('name', '9.8.7', 3)]
I want to get a new list2 like this (joining first element with second element's second entry);
list2 = [('my2', 2),('name8', 3)]
As a first step, I am checking to join the first two elements in the tuple as follow,
for i,j,k in list1:
#print(i,j,k)
x = j.split('.')[1]
y = str(i).join(x)
print(y)
but I get this
2
8
I was expecting this;
my2
name8
what I am doing wrong? Is there any good way to do this? a simple way..
try
y = str(i) + str(x)
it should works.
The str(i).join(x), means that you see x as an iterable of strings (a string is an iterable of strings), and you are going to construct a string by adding i in between the elements of x.
You probably want to print('{}{}'.format(i+x)) however:
for i,j,k in list1:
x = j.split('.')[1]
print('{}{}'.format(i+x))
Try this:
for x in list1:
print(x[0] + x[1][2])
or
for x in list1:
print(x[0] + x[1].split('.')[1])
output
# my2
# name8
You should be able to achieve this via f strings and list comprehension, though it'll be pretty rigid.
list_1 = [('my', '1.2.3', 2),('name', '9.8.7', 3)]
# for item in list_1
# create tuple of (item[0], item[1].split('.')[1], item[2])
# append to a new list
list_2 = [(f"{item[0]}{item[1].split('.')[1]}", f"{item[2]}") for item in list_1]
print(list_2)
List comprehensions (and dict comprehensions) are some of my favorite things about python3
https://www.pythonforbeginners.com/basics/list-comprehensions-in-python
https://www.digitalocean.com/community/tutorials/understanding-list-comprehensions-in-python-3
Going with the author's theme,
list1 = [('my', '1.2.3', 2),('name', '9.8.7', 3)]
for i,j,k in list1:
extracted = j.split(".")
y = i+extracted[1] # specified the index here instead
print(y)
my2
name8
[Program finished]
Related
I have a list
flat_list =['53295,-46564.2', '53522.6,-46528.4', '54792.9,-46184', '55258.7,-46512.9', '55429.4,-48356.9', '53714.5,-50762.8']
How can I convert it into
[[53295,-46564.2], [53522.6,-46528.4], [54792.9,-46184], [55258.7,-46512.9], [55429.4,-48356.9], [53714.5,-50762.8]]
I tried
l = [i.strip("'") for i in flat_list]
nothing works.
l = [i.strip("'") for i in flat_list]
coords = [map(float,i.split(",")) for i in flat_list]
print(coords)
gives me <map object at 0x7f7a7715d2b0>
Why complicate things?
Without any builtins such as map and itertools, this approach with a nested list comprehension should be a relatively simple and efficient one.
flat_list = ['53295,-46564.2', '53522.6,-46528.4', '54792.9,-46184', '55258.7,-46512.9', '55429.4,-48356.9',
'53714.5,-50762.8']
result = [float(f) for pair in flat_list for f in pair.split(',')]
print(result)
Output:
[53295.0, -46564.2, 53522.6, -46528.4, 54792.9, -46184.0, 55258.7, -46512.9, 55429.4, -48356.9, 53714.5, -50762.8]
To instead end up with a list of lists, you can change the order of the for statements and then add braces around the sub-list for each str.split result, as shown below:
flat_list = ['53295,-46564.2', '53522.6,-46528.4', '54792.9,-46184', '55258.7,-46512.9', '55429.4,-48356.9',
'53714.5,-50762.8']
result = [[float(f) for f in pair.split(',')] for pair in flat_list]
print(result)
Output:
[[53295.0, -46564.2], [53522.6, -46528.4], [54792.9, -46184.0], [55258.7, -46512.9], [55429.4, -48356.9], [53714.5, -50762.8]]
Edit after your comment: to get a list of lists you can use
list2 = [[float(f) for f in el.split(",")] for el in flat_list]
or
list2 = [list(map(float,el.split(","))) for el in flat_list]
Deprecated: If you are okay with 2 operations instead of a one-liner, go with:
list2 = map(lambda el: el.split(","), flat_list)
list3 = [float(el) for sublist in list2 for el in sublist]
or
import itertools
list2 = map(lambda el: el.split(","), flat_list)
list3 = list(map(float, itertools.chain.from_iterable(list2)))
I see that the coordinates come in pairs, so in order to convert them to an integer or float first we need to split them so they become single numbers.
flat_list =['53295,-46564.2', '53522.6,-46528.4', '54792.9,-46184', '55258.7,-46512.9', '55429.4,-48356.9', '53714.5,-50762.8']
coordinates = []
for pair in flat_list:
coordinates.extend(pair.split(','))
result = [float(x) for x in coordinates]
This is not the shortest way to do it, but I think it does the job.
list1 = ['/mnt/1m/a_pre.geojson','/mnt/2m/b_pre.geojson']
list2 = ['/mnt/1m/a_post.geojson']
I have multiple lists and I want to find all the elements of list1 which do not have entry in list2 with a filtering condition.
The condition is it should match 'm' like 1m,2m.. and name of geojson file excluding 'pre or post' substring.
For in e.g. list1 '/mnt/1m/a_pre.geojson' is processed but '/mnt/2m/b_pre.geojson' is not so the output should have a list ['/mnt/2m/b_pre.geojson']
I am using 2 for loops and then splitting the string which I am sure is not the only one and there might be easier way to do this.
for i in list1:
for j in list2:
pre_tile = i.split("/")[-1].split('_pre', 1)[0]
post_tile = j.split("/")[-1].split('_post', 1)[0]
if pre_tile == post_tile:
...
I believe you have similar first part of the file paths. If so, you can try this:
list1 = ['/mnt/1m/a_pre.geojson','/mnt/2m/b_pre.geojson']
list2 = ['/mnt/1m/a_post.geojson']
res = [x for x in list1 if x[:7] not in [y[:7] for y in list2]]
res:
['/mnt/2m/b_pre.geojson']
If I understand you correctly, using a regular expression to do this kind of string manipulation can be fast and easy.
Additionally, to do multiple member-tests in list2, it's more efficient to convert the list to a set.
import re
list1 = ['/mnt/1m/a_pre.geojson', '/mnt/2m/b_pre.geojson']
list2 = ['/mnt/1m/a_post.geojson']
pattern = re.compile(r'(.*?/[0-9]m/.*?)_pre.geojson')
set2 = set(list2)
result = [
m.string
for m in map(pattern.fullmatch, list1)
if m and f"{m[1]}_post.geojson" not in set2
]
print(result)
I have a large list like this:
mylist = [['pears','apples','40'],['grapes','trees','90','bears']]
I'm trying to remove all numbers within the lists of this list. So I made a list of numbers as strings from 1 to 100:
def integers(a, b):
return list(range(a, b+1))
numb = integers(1,100)
numbs = []
for i in range(len(numb)):
numbs.append(str(numb[i])) # strings
numbs = ['1','2',....'100']
How can I iterate through lists in mylist and remove the numbers in numbs? Can I use list comprehension in this case?
If number is always in the end in sublist
mylist = [ x[:-1] for x in mylist ]
mylist = [[item for item in sublist if item not in numbs] for sublist in mylist] should do the trick.
However, this isn't quite what you've asked. Nothing was actually removed from mylist, we've just built an entirely new list and reassigned it to mylist. Same logical result, though.
If numbers are always at the end and only once, you can remove the last item like:
my_new_list = [x[:-1] for x in mylist]
If there is more (of if they are not ordered), you have to loop thru each elements, in that case you can use:
my_new_list = [[elem for elem in x if elem not in integer_list] for x in mylist]
I would also recommend to generate the list of interger as follow :
integer_list = list(map(str, range(1, 100)))
I hope it helps :)
Instead of enumerating all the integers you want to filter out you can use the isdigit to test each string to see if it really is only numbers:
mylist = [['pears','apples','40'],['grapes','trees','90','bears']]
mylist2 = [[x for x in aList if not x.isdigit()] for aList in mylist]
print mylist2
[['pears', 'apples'], ['grapes', 'trees', 'bears']]
If you have the following list:
mylist = [['pears','apples','40'],['grapes','trees','90','bears']]
numbs = [str(i) for i in range(1, 100)]
Using list comprehension to remove element in numbs
[[l for l in ls if l not in numbs] for ls in mylist]
This is a more general way to remove digit elements in a list
[[l for l in ls if not l.isdigit()] for ls in mylist]
I need to concatenate an item from a list with an item from another list. In my case the item is a string (a path more exactly). After the concatenation I want to obtain a list with all the possible items resulted from concatenation.
Example:
list1 = ['Library/FolderA/', 'Library/FolderB/', 'Library/FolderC/']
list2 = ['FileA', 'FileB']
I want to obtain a list like this:
[
'Library/FolderA/FileA',
'Library/FolderA/FileB',
'Library/FolderB/FileA',
'Library/FolderB/FileB',
'Library/FolderC/FileA',
'Library/FolderC/FileB'
]
Thank you!
In [11]: [d+f for (d,f) in itertools.product(list1, list2)]
Out[11]:
['Library/FolderA/FileA',
'Library/FolderA/FileB',
'Library/FolderB/FileA',
'Library/FolderB/FileB',
'Library/FolderC/FileA',
'Library/FolderC/FileB']
or, slightly more portably (and perhaps robustly):
In [16]: [os.path.join(*p) for p in itertools.product(list1, list2)]
Out[16]:
['Library/FolderA/FileA',
'Library/FolderA/FileB',
'Library/FolderB/FileA',
'Library/FolderB/FileB',
'Library/FolderC/FileA',
'Library/FolderC/FileB']
You can use a list comprehension:
>>> [d + f for d in list1 for f in list2]
['Library/FolderA/FileA', 'Library/FolderA/FileB', 'Library/FolderB/FileA', 'Library/FolderB/FileB', 'Library/FolderC/FileA', 'Library/FolderC/FileB']
You may want to use os.path.join() instead of simple concatenation though.
The built-in itertools module defines a product() function for this:
import itertools
result = itertools.product(list1, list2)
The for loop can do this easily:
my_list, combo = [], ''
list1 = ['Library/FolderA/', 'Library/FolderB/', 'Library/FolderC/']
list2 = ['FileA', 'FileB']
for x in list1:
for y in list2:
combo = x + y
my_list.append(combo)
return my_list
You can also just print them:
list1 = ['Library/FolderA/', 'Library/FolderB/', 'Library/FolderC/']
list2 = ['FileA', 'FileB']
for x in list1:
for y in list2:
print str(x + y)
For example, I have a list like this:
list1 = ['good', 'bad', 'tall', 'big']
list2 = ['boy', 'girl', 'guy', 'man']
and I want to make a list like this:
list3 = ['goodboy', 'badgirl', 'tallguy', 'bigman']
I tried something like these:
list3=[]
list3 = list1 + list2
but this would only contain the value of list1
So I used for :
list3 = []
for a in list1:
for b in list2:
c = a + b
list3.append(c)
but it would result in too many lists(in this case, 4*4 = 16 of them)
You can use list comprehensions with zip:
list3 = [a + b for a, b in zip(list1, list2)]
zip produces a list of tuples by combining elements from iterables you give it. So in your case, it will return pairs of elements from list1 and list2, up to whichever is exhausted first.
A solution using a loop that you try is one way, this is more beginner friendly than Xions solution.
list3 = []
for index, item in enumerate(list1):
list3.append(list1[index] + list2[index])
This will also work for a shorter solution. Using map() and lambda, I prefer this over zip, but thats up to everyone
list3 = map(lambda x, y: str(x) + str(y), list1, list2);
for this or any two list of same size you may also use like this:
for i in range(len(list1)):
list3[i]=list1[i]+list2[i]
Using zip
list3 = []
for l1,l2 in zip(list1,list2):
list3.append(l1+l2)
list3 = ['goodboy', 'badgirl', 'tallguy', 'bigman']