I have a list of strings and I want to extract the first 6 characters of each string and store them in a new list.
I can loop through the list and extract the first 6 characters and append them to a new list.
y = []
for i in range(len(x)):
y.append(int(x[i][0:6]))
I want to know if there is an elegant one line solution for that. I tried the following:
y = x[:][0:6]
But it returns a list of the first 6 strings.
Try this:
y = [z[:6] for z in x]
This was the same as this:
y = [] # make the list
for z in x: # loop through the list
y.append(z[:6]) # add the first 6 letters of the string to y
Yes, there is. You can use the following list-comprehention.
newArray = [x[:6] for x in y]
Slicing has the following syntax: list[start:end:step]
Arguments:
start - starting integer where the slicing of the object starts
stop - integer until which the slicing takes place. The slicing stops at index stop - 1.
step - integer value which determines the increment between each index for slicing
Examples:
list[start:end] # get items from start to end-1
list[start:] # get items from start to the rest of the list
list[:end] # get items from the beginning to the end-1 ( WHAT YOU WANT )
list[:] # get a copy of the original list
if the start or end is -negative, it will count from the end
list[-1] # last item
list[-2:] # last two items
list[:-2] # everything except the last two items
list[::-1] # REVERSE the list
Demo:
let's say I have an array = ["doctorWho","Daleks","Cyborgs","Tardis","SonicSqrewDriver"]
and I want to get the first 3 items.
>>> array[:3] # 0, 1, 2 (.. then it stops)
['doctorWho', 'Daleks', 'Cyborgs']
(or I decided to reverse it):
>>> array[::-1]
['SonicSqrewDriver', 'Tardis', 'Cyborgs', 'Daleks', 'doctorWho']
(now i'd like to get the last item)
>>> array[-1]
'SonicSqrewDriver'
(or last 3 items)
>>> array[-3:]
['Cyborgs', 'Tardis', 'SonicSqrewDriver']
This might help
stringList = ['abcdeffadsff', 'afdfsdfdsfsdf', 'fdsfdsfsdf', 'gfhthtgffgf']
newList = [string[:6] for string in stringList]
You can also use map for this:
list(map(lambda w: int(w[:6]), x))
and using itertools.islice:
list(map(lambda w:list(int(itertools.islice(w, 6))), x))