input = '1+2++3+++4++5+6+7++8+9++10'
string = input.split('+')
print(string)
when we run this code the output is ['1', '2', '', '3', '', '', '4', '', '5', '6', '7', '', '8', '9', '', '10']
But i want to split the string with no blank like ['1', '2', '3', '4', '5', '6', '7', '8', '9', '10']
Is there any function or method to remove blanks without using for loop like
for i in string:
if i == '':
string.remove(i)
Generate a list based on the output of split, and only include the elements which are not None
You can achieve this in multiple ways. The cleanest way here would be to use regex.
Regex:
import re
re.split('\++', inp)
#['1', '2', '3', '4', '5', '6', '7', '8', '9', '10']
List Comprehension:
inp = '1+2++3+++4++5+6+7++8+9++10'
[s for s in inp.split('+') if s]
#['1', '2', '3', '4', '5', '6', '7', '8', '9', '10']
Loop & Append:
result = []
for s in inp.split('+'):
if s:
result.append(s)
result
#['1', '2', '3', '4', '5', '6', '7', '8', '9', '10']
Simplest way:
customStr="1+2++3+++4++5+6+7++8+9++10"
list( filter( lambda x : x!="" ,customStr.split("+") ) )
Related
n=10
fun=list(map(lambda x:[j for j in range(x)],n))
print(fun)
expected output is:
['0', '1', '2', '3', '4', '5', '6', '7', '8', '9']
# using map (map works on an iterable)
n=10
fun=lambda x: (range(x)) # remember this is a function (so call it)
fun=list(map(str, fun(n)))
print(fun)
# directly
n=10
fun=list(map(str, (range(n))))
print(fun)
['0', '1', '2', '3', '4', '5', '6', '7', '8', '9']
['0', '1', '2', '3', '4', '5', '6', '7', '8', '9']
Python docs for reference:
map(): https://docs.python.org/3/library/functions.html#map
range(): https://docs.python.org/3/library/functions.html#func-range
lambda(): https://docs.python.org/3/library/ast.html?highlight=lambda#ast.Lambda
I have a list that contains a set of strings like this:
list = ['235,ACCESS,19841136,22564960,4291500,20,527434,566876','046,ALLOWED,24737321,27863065,1086500,3,14208500,14254500']
I'm trying to make the elements of the list a sublist but without splitting the string.
I tried new_list = list(map(list, list)). This is the result taking as reference the first element of the list:
print(new_list[0]):
[['2', '3', '5', ',', 'A', 'C', 'C', 'E', 'S',',','1', '9', '8', '4', '1', '1', '3', '6', ',', '2', '2', '5', '6', '4', '9', '6', '0', ',', '4', '2', '9', '1', '5', '0', '0', ',', '2', '0', ',', '5', '2', '7', '4', '3', '4', ',', '5', '6', '6', '8', '7', '6']]
I would like this output:
print(new_list[0]):
[[235,'ACCESS',19841136,22564960,4291500,20,527434,566876]]
Thanks in advance for your help!
You can try split() with delimiter , like this -
new_list = [i.split(',') for i in list]
print (new_list[0])
Output:
['235', 'ACCESS', '19841136', '22564960', '4291500', '20', '527434', '566876']
One thing is that here the numbers are also represented as string. If you want integers instead you can use isdigit() method like this -
new_list = [[int(e) if e.isdigit() else e for e in i.split(',') ]for i in list]
print(new_list[0])
Output:
[235, 'ACCESS', 19841136, 22564960, 4291500, 20, 527434, 566876]
Also, please try to avoid naming your list list
This question already has answers here:
How do I clone a list so that it doesn't change unexpectedly after assignment?
(24 answers)
Closed 6 years ago.
I have two nested for loops and two lists, I want one of tle list to re-initialize after one iteration of inner loop.
def test():
i = ['1','5','9','3','6','4']
for x in xrange(0,len(i)):
j = ['6', '7', '9', '3']
newi = i
for y in xrange(0,len(j)):
newi[x] = j[y]
print "i", i
print "end of one iteration on finner loop"
print "newi", newi
test()
Its a dummy code, I want a clean new instance of newi to be that of i after one iteration of inner loop, currently it preserver the value of inner loop
current output:
i ['6', '5', '9', '3', '6', '4']
i ['7', '5', '9', '3', '6', '4']
i ['9', '5', '9', '3', '6', '4']
i ['3', '5', '9', '3', '6', '4']
end of one iteration on inner loop
newi ['3', '5', '9', '3', '6', '4']
i ['3', '6', '9', '3', '6', '4']
i ['3', '7', '9', '3', '6', '4']
i ['3', '9', '9', '3', '6', '4']
i ['3', '3', '9', '3', '6', '4']
end of one iteration on inner loop
newi ['3', '3', '9', '3', '6', '4']
i ['3', '3', '6', '3', '6', '4']
i ['3', '3', '7', '3', '6', '4']
i ['3', '3', '9', '3', '6', '4']
i ['3', '3', '3', '3', '6', '4']
end of one iteration on inner loop
newi ['3', '3', '3', '3', '6', '4']
i ['3', '3', '3', '6', '6', '4']
i ['3', '3', '3', '7', '6', '4']
i ['3', '3', '3', '9', '6', '4']
i ['3', '3', '3', '3', '6', '4']
end of one iteration on inner loop
newi ['3', '3', '3', '3', '6', '4']
i ['3', '3', '3', '3', '6', '4']
i ['3', '3', '3', '3', '7', '4']
i ['3', '3', '3', '3', '9', '4']
i ['3', '3', '3', '3', '3', '4']
end of one iteration on inner loop
newi ['3', '3', '3', '3', '3', '4']
i ['3', '3', '3', '3', '3', '6']
i ['3', '3', '3', '3', '3', '7']
i ['3', '3', '3', '3', '3', '9']
i ['3', '3', '3', '3', '3', '3']
end of one iteration on inner loop
newi ['3', '3', '3', '3', '3', '3']
Instead of:
newi = i
replace with:
newi = list(i) # list(i) creates another copy i
I know that you can swap 2 single indexes in Python
r = ['1', '2', '3', '4', '5', '6', '7', '8']
r[2], r[4] = r[4], r[2]
output:
['1', '2', '5', '4', '3', '6', '7', '8']
But why can't you swap 2 slices of indexes in python?
r = ['1', '2', '3', '4', '5', '6', '7', '8']
I want to swap the numbers 3 + 4 with 5 + 6 + 7 in r:
r[2:4], r[4:7] = r[4:7], r[2:4]
output:
['1', '2', '5', '6', '3', '4', '7', '8']
expected output:
['1', '2', '5', '6', '7', '3', '4', '8']
What did I wrong?
output:
The slicing is working as it should. You are replacing slices of different lengths. r[2:4] is two items, and r[4:7] is three items.
>>> r = ['1', '2', '3', '4', '5', '6', '7', '8']
>>> r[2:4]
['3', '4']
>>> r[4:7]
['5', '6', '7']
So when ['3', '4'] is replaced, it can only fit ['5', '6'], and when ['5', '6', '7'] is replaced, it only gets ['3', '4']. So you have ['1', '2',, then the next two elements are the first two elements from ['5', '6', '7'] which is just ['5', '6', then the two elements from ['3', '4' go next, then the remaining '7', '8'].
If you want to replace the slices, you have to start slices at the right places and allocate an appropriate size in the array for each slice:
>>> r = ['1', '2', '3', '4', '5', '6', '7', '8']
>>> r[2:5], r[5:7] = r[4:7], r[2:4]
>>> r
['1', '2', '5', '6', '7', '3', '4', '8']
old index: 4 5 6 2 3
new index: 2 3 4 5 6
Think of this:
r[2:4], r[4:7] = r[4:7], r[2:4]
as similar to this:
original_r = list(r)
r[2:4] = original_r[4:7]
r[4:7] = original_r[2:4]
So, by the time it gets to the third line of that, the 4th element isn't what you think it is anymore... You replaced '3', '4' with '5', '6', '7', and now the [4:7] slice starts with that '7'.
>>> r = ['1', '2', '3', '4', '5', '6', '7', '8']
>>> r[2:5], r[5:7] = r[4:7], r[2:4]
>>> r
['1', '2', '5', '6', '7', '3', '4', '8']
In your code:
>>> r[2:4], r[4:7] = r[4:7], r[2:4]
You are assigning r[4:7] which have 3 elements to r[2:4] which have only 2.
In the code I posted:
>>> >>> r[2:5], r[5:7] = r[4:7], r[2:4]
r[4:7] which is ['5', '6', '7'], replaces
r[2:5] which is ['3', '4', '5']
r resulting in ['1', '2', '5', '6', '7', '6', '7', '8']
and then:
r[2:4] which was ['3', '4'], replaces
r[5:7] which is ['6', '7']
So final result being:
['1', '2', '5', '6', '7', '3', '4', '8']
I need to read in a CSV file, from Excel, whose rows may be an arbitrary length.
The problem is the python retains these blank entries, but need to delete them for a future algorithm. Below is the output, I don't want the blank entries.
['5', '1', '5', '10', '4', '']
['3', '1', '5', '10', '2', '']
['6', '1', '5', '10', '5', '2']
['9', '10', '5', '10', '7', '']
['8', '5', '5', '10', '7', '']
['1', '1', '5', '10', '', '']
['2', '1', '5', '10', '1', '']
['7', '1', '5', '10', '6', '4']
['4', '1', '5', '10', '3', '1']
Here's a list comprehension integrated with the csv library:
import csv
with open('input.csv') as in_file:
reader = csv.reader(in_file)
result = [[item for item in row if item != ''] for row in reader]
print result
This is about as verbose a function as I could write to do what you want. There are certainly slicker ways.
def remove_blanks(a_list):
new_list = []
for item in a_list:
if item != "":
new_list.append(item)
return new_list
List comprehension version:
a = ['5', '1', '5', '10', '4', '']
[x for x in a if x != '']
Out[19]: ['5', '1', '5', '10', '4']
You may be better served by filtering at the csv read step instead.