Copy a list of list by value and not reference

Because python passes lists by reference

This means that when you write “b=a” you’re saying that a and b are the same object, and that when you change b you change also a, and viceversa

A way to copy a list by value:

new_list = old_list[:]

If the list contains objects and you want to copy them as well, use generic copy.deepcopy():

import copy
new_list = copy.deepcopy(old_list)

Related Posts:

  1. TypeError: ‘int’ object is not subscriptable
  2. TypeError: ‘int’ object is not callable
  3. TypeError: ‘int’ object is not callable
  4. TypeError: ‘int’ object is not callable
  5. List changes unexpectedly after assignment. Why is this and how can I prevent it?
  6. Cannot find module cv2 when using OpenCV
  7. Cannot find module cv2 when using OpenCV
  8. Python ‘If not’ syntax [duplicate]
  9. Converting dictionary to JSON
  10. IndexError: tuple index out of range —– Python
  11. sklearn error ValueError: Input contains NaN, infinity or a value too large for dtype(‘float64’)
  12. What is the naming convention in Python for variable and function names?
  13. TypeError: cannot perform reduce with flexible type
  14. How to copy a dictionary and only edit the copy
  15. Could not find a version that satisfies the requirement tensorflow
  16. ln (Natural Log) in Python
  17. How do I check if a variable exists?
  18. ImportError: numpy.core.multiarray failed to import
  19. Unable to plot Double Bar, Bar plot using pyplot for ndarray
  20. Cannot find module cv2 when using OpenCV
  21. Convert list to tuple in Python
  22. ImportError: numpy.core.multiarray failed to import
  23. How to remove \xa0 from string in Python?
  24. Why are Python’s ‘private’ methods not actually private?
  25. How to create a new text file using Python
  26. TypeError: write() argument must be str, not bytes (Python 3 vs Python 2 )
  27. python socket.error: [Errno 98] Address already in use
  28. How to import files in python using sys.path.append?
  29. Check string “None” or “not” in Python 2.7
  30. Change figure size and figure format in matplotlib
  31. how to update spyder on anaconda
  32. how does \r (carriage return) work in Python
  33. What is Python buffer type for?
  34. AttributeError(“‘str’ object has no attribute ‘read'”)
  35. IndexError: index 1 is out of bounds for axis 0 with size 1/ForwardEuler
  36. Python Save to file
  37. Add list to set?
  38. TypeError: unsupported operand type(s) for -: ‘list’ and ‘list’
  39. ImportError: No module named scipy
  40. AttributeError: ‘datetime’ module has no attribute ‘strptime’
  41. Python add item to the tuple
  42. Checking whether pip is installed?
  43. Converting binary to decimal integer output
  44. Decoding UTF-8 strings in Python
  45. How can I read pdf in python?
  46. No module named setuptools
  47. How to have an array of arrays in Python
  48. Importing variables from another file?
  49. ValueError: unsupported pickle protocol: 3, python2 pickle can not load the file dumped by python 3 pickle?
  50. ValueError: unsupported pickle protocol: 3, python2 pickle can not load the file dumped by python 3 pickle?
  51. AttributeError(“‘str’ object has no attribute ‘read'”)
  52. How to check if type of a variable is string?
  53. How to use 2to3 properly for python?
  54. Why does using from __future__ import print_function breaks Python2-style print?
  55. How to fix: “UnicodeDecodeError: ‘ascii’ codec can’t decode byte”
  56. Python – ‘ascii’ codec can’t decode byte
  57. Python Error – int object has no attribute
  58. Loading a file with more than one line of JSON into Pandas
  59. Type error Unhashable type:set
  60. What is the difference between json.load() and json.loads() functions
  61. Viewing all defined variables
  62. Python: count repeated elements in the list
  63. How to XOR two strings in Python
  64. Printing variables in Python 3.4
  65. Why I get ‘list’ object has no attribute ‘items’?
  66. Python 101: Can’t open file: No such file or directory
  67. TypeError: argument of type ‘NoneType’ is not iterable
  68. scrapy run spider from script
  69. Python NameError, variable ‘not defined’
  70. python error: TypeError: an integer is required
  71. Python Requests – No connection adapters
  72. How to detect key presses?
  73. Numpy, multiply array with scalar
  74. TypeError: coercing to Unicode: need string or buffer, list found
  75. ‘virtualenv’ is not recognized as an internal or external command, operable program or batch file
  76. ImportError: cannot import name NUMPY_MKL
  77. Getting the name of a variable as a string
  78. Python: Pandas pd.read_excel giving ImportError: Install xlrd >= 0.9.0 for Excel support
  79. TypeError: super() takes at least 1 argument (0 given) error is specific to any python version?
  80. Split string using a newline delimiter with Python
  81. No module named urllib3
  82. Convert string to variable name in python
  83. AttributeError: ‘tuple’ object has no attribute
  84. Adding +1 to a variable inside a function
  85. What is the purpose of the single underscore “_” variable in Python?
  86. dump() missing 1 required positional argument: ‘fp’ in python json
  87. How to open html file?
  88. “Python version 2.7 required, which was not found in the registry” error when attempting to install netCDF4 on Windows 8
  89. Installing scipy for python 2.7
  90. Install py2exe for python 2.7 over pip: this package requires Python 3.3 or later
  91. ImportError: No module named IPython
  92. Does python have header files like C/C++?
  93. How can I install a .egg Python package on Windows (attempt using easy_install not working)
  94. Symbol not found: __PyCodecInfo_GetIncrementalDecoder
  95. Python 2.7 mixing iteration and read methods would lose data
  96. What does an ‘r’ represent before a string in python?
  97. Cannot remove entries from nonexistent file
  98. Set variable in jinja
  99. Python list index out of range on return value of split
  100. Python: OSError: [Errno 2] No such file or directory: ”

Leave a Comment

techhipbettruvabetnorabahisbahis forumutaraftarium24eduedueduseduedusedusedusedusedusedu