Replace substring# replace all characters "a" with "x"
"a1 a2 a3 a4".replace("a","x")x1 x2 x3 x4 replace file ending ".txt" with ".csv"
mydata.csv
remove file ending ".txt"
mydata
Split and merge text strings>>> 'a1,a2,a3'.split(',')['a1', 'a2', 'a3']get filename (get first list element)
>>> 'filename.txt.bz2'.split('.')[0]'filename'split() by default used all whitespace characters (space, tab \t, new line \n, \r, ...)join - to concatenate a list to a string
>>> ','.join(['a1', 'a2', 'a3']) # comma separated'a1,a2,a3' >>> ' '.join(['a1', 'a2', 'a3']) # space separated'a1 a2 a3' concatenate strings
>>> 'hello' + ' ' + 'world''hello world' for many strings, better use join()
>>> ''.join(['hello','world'])'helloworld' >>> ' '.join(['hello','world'])'hello world' # add prefix, only if not already present
s = 'hello world'prefix = 'hello'if not s.startswith(prefix): s = prefix + ' ' + s'hello world'
length of string
>>> len('hello')5 sorted list
>>> sorted(['C', 'b', 'd','A'], key=str.lower)['A', 'b', 'C', 'd']sort list in descending order >>> sorted([4, 1, 3, 2], reverse=True)[4, 3, 2, 1]convert strings to numbers (and back as string) >>> int('23') 23 >>> float('23.1')23.1 >>> str(23)'23' see also: format() format('hello','>20')' hello' convert all strings in a list into int numbers
s = ['4', '1', '3', '2']n = [int(x) for x in s][4, 1, 3, 2] see also: List Comprehension
check for substring
>>> 'day' in 'Friday'True get index location of substring
'Friday'.index('day')3 s='hello'[idx for idx, letter in enumerate(s) if letter == 'l'][2, 3] find a substring in list items
>>> dates = ['May 2015','January 2012','Dezember 2015','June 2014']>>> dates2015= [s for s in dates if '2015' in s]['May 2015', 'Dezember 2015'] check if any substring is present in list items
print('yes, 2015 is present')read more: |