I have a list:
rows=['1\t0.00032822\n', '2\t0.00029311\n', '3\t0.0002048\n',...]
and i want to have a list with the numbers only:
['0.00032822', '0.00029311', '0.0002048',...].
Something like:
list = [sliceAppropiate(x) for x in rows]
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2 Answers
Use a list comprehension:
>>> rows = ['1\t0.00032822\n', '2\t0.00029311\n', '3\t0.0002048\n']
>>> [r.split()[1] for r in rows]
['0.00032822', '0.00029311', '0.0002048']
What this does is:
- Go through each item in
rowsin turn, - Give it the name
r, - Split each
rinto a list withsplit(), by cutting at whitespace (which can be spaces, tabs or newlines), - Take item 1 from that list (where item 0 is the first one, because Python uses zero-based indexing).
5 Comments
John
So, split by default "splits" in numbers! Nice!
Zero Piraeus
@JohnZobolas Actually it splits on whitespace - from the docs I linked to: "If sep is not specified or is None, a different splitting algorithm is applied: runs of consecutive whitespace are regarded as a single separator, and the result will contain no empty strings at the start or end if the string has leading or trailing whitespace."
Aaron Hall
@JohnZobolas split splits on whitespace, which \t and \n are.
John
Thanks Zero and Aaron! I also used something like this to have the sum of the list of numbers: sum([(float) (r.split()[1]) for r in rows])
Zero Piraeus
@JohnZobolas great! You can make that a little more efficient and readable by dropping the parentheses around
float, and the square brackets around the listcomp (turning into a generator expression): sum(float(r.split()[1]) for r in rows)Here is a very simple code that do it for you:
list = []
for i in range(len(rows)): # from 0 to len(rows) - 1
list[i] = rows[i].split('\t')[1]
If need float numbers use float function:
float(rows[i].split('\t')[1])
1 Comment
John
Thanks! I believe that the answer with the list comprehension is better-more compact and easy to understand!