Python Removing spaces from list objects

Question

I have a list of objects appended from a mysql database and contain spaces  I wish to remove the spaces such as below  but the code im using doesnt work   hello     999     666     k       for i in hello      str i  replace             k append i   print k

User · Answer

replace   does not operate in-place  you need to assign its result to something  Also  for a more concise syntax  you could supplant your for loop with a one-liner  hello no spaces   map lambda x  x replace           hello

User · Answer

String methods return the modified string   k    x replace          for x in hello

User · Answer

for element in range 0 len hello          d element    hello element  strip

User · Answer

result   map str strip  hello

User · Answer

Strings in Python are immutable  meaning that their data cannot be modified  so the replace method doesn t modify the string - it returns a new string  You could fix your code as follows   for i in hello      j   i replace             k append j    However a better way to achieve your aim is to use a list comprehension  For example the following code removes leading and  trailing spaces from every string in the list using strip   hello    x strip      for x in hello

User · Answer

List comprehension  num strip   for num in hello  is the fastest    gt  gt  gt  import timeit  gt  gt  gt  hello     999     666      gt  gt  gt  t1   lambda  map str strip  hello   gt  gt  gt  timeit timeit t1  1 825870468015296   gt  gt  gt  t2   lambda  list map str strip  hello    gt  gt  gt  timeit timeit t2  2 2825958750515269   gt  gt  gt  t3   lambda   num strip   for num in hello   gt  gt  gt  timeit timeit t3  1 4320335103944899   gt  gt  gt  t4   lambda   num replace          for num in hello   gt  gt  gt  timeit timeit t4  1 7670568718943969

User · Answer

Presuming that you don t want to remove internal spaces   def normalize space s          Return s stripped of leading trailing whitespace     and with internal runs of whitespace replaced by a single SPACE          This should be a str method  -      return     join s split     replacement    normalize space i  for i in hello

[python] Python: Removing spaces from list objects

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