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I have a two-dimensional list like this:
[[1, 6], [2, 5], [3, 7], [5, 2], [6, 1], [7, 3], [8, 9], [9, 8]]
I want to remove all the sublists that are duplicates but in reverse order (ie: [1, 6] and [6, 1], [3, 7] and [7, 3]).
The result should be:
[[1, 6], [2, 5], [3, 7], [8, 9]]
You can use set and frozenset:
lst = [[1, 6], [2, 5], [3, 7], [5, 2], [6, 1], [7, 3], [8, 9], [9, 8]]
output = set(map(frozenset, lst))
print(output)
# {frozenset({1, 6}), frozenset({2, 5}), frozenset({3, 7}), frozenset({8, 9})}
If you want to have a list of lists, then you can append the following:
output = list(map(list, output))
print(output)
# [[1, 6], [2, 5], [3, 7], [8, 9]]
You can do this easily by checking if the sorted list is already had already been added. Like this:
data = [[1, 6], [2, 5], [3, 7], [5, 2], [6, 1], [7, 3], [8, 9], [9, 8]]
new_data = []
for lst in data:
if sorted(lst) not in new_data:
new_data.append(lst)
print(new_data) # => [[1, 6], [2, 5], [3, 7], [8, 9]]
This works because [1, 6] and [6, 1] return the same sorted list.
I have three arrays I1,I2,I3 with shape (1,9,2). I am trying to append but there is an error. The new array should have shape (3,9,2)
import numpy as np
I1 = np.array([[[0, 2],
[2, 3],
[2, 5],
[3, 4],
[3, 6],
[4, 1],
[4, 7],
[5, 6],
[6, 7]]])
I2 = np.array([[[1, 1],
[2, 3],
[2, 5],
[3, 4],
[3, 6],
[4, 1],
[4, 7],
[5, 6],
[6, 7]]])
I3 = np.array([[[2, 2],
[2, 3],
[2, 5],
[3, 4],
[3, 6],
[4, 1],
[4, 7],
[5, 6],
[6, 7]]])
I=np.append(I1,I2,I3,axis=0)
The error is
in <module>
Iit=np.append(Iit1,Iit2,Iit3,axis=0)
File "<__array_function__ internals>", line 4, in append
TypeError: _append_dispatcher() got multiple values for argument 'axis'
Use I=np.concatenate([I1,I2,I3],axis=0) rather than append. Append does what you'd expect from a list (and try not to use it in numpy, anyway, for memory allocation reasons!)`
A different way from #Dominik is
I = np.stack((I1,I2,I3))
stack creates a new axis.
If I have a dictionary say:
dictionary = {'blue': [ [0,1], [0,2] ] , 'red': [ [0,3], [0,4] ] }
How would I move a blue value say [0,1] to the red without leaving behind a copy in blue without hardcoding the delete ( so if I had a different list of a hundred values and want to move a value from one key to another it should also work in that way ).
I want the output to look this:
dictionary = {'blue': [ [0,2] ] , 'red': [ [0,3], [0,4], [0,1] ] }
EDIT:
Ok, since people are asking for context:
My dictionary is:
d = {' . ': [[0, 1], [0, 2], [0, 3], [0, 4], [0, 5], [0, 6], [0, 7], [0, 8], [0, 9], [1, 1],
[1, 2], [1, 3], [1, 4], [1, 5], [1, 6], [1, 7], [1, 8], [1, 9], [2, 1], [2, 2],
[2, 3], [2, 4], [2, 5], [2, 6], [2, 7], [2, 8], [2, 9], [3, 1], [3, 2], [3, 3],
[3, 4], [3, 5], [3, 6], [3, 7], [3, 8], [3, 9], [4, 0], [4, 1], [4, 2], [4, 3],
[4, 4], [4, 5], [4, 6], [4, 7], [4, 8], [4, 9], [5, 0], [5, 1], [5, 2], [5, 3],
[5, 4], [5, 5], [5, 6], [5, 7], [5, 8], [5, 9], [6, 0], [6, 1], [6, 2], [6, 3],
[6, 4], [6, 5], [6, 6], [6, 7], [6, 8], [6, 9], [7, 0], [7, 1], [7, 2], [7, 3],
[7, 4], [7, 5], [7, 6], [7, 7], [7, 8], [7, 9], [8, 0], [8, 1], [8, 2], [8, 3],
[8, 4], [8, 5], [8, 6], [8, 7], [8, 8], [8, 9], [9, 0], [9, 1], [9, 2], [9, 3],
[9, 4], [9, 5], [9, 6], [9, 7], [9, 8], [9, 9]],
' X ': [[0, 0], [1, 0], [2, 0], [3, 0]]}
I want to move [3,0] from ' X ' to ' . ' and don't want it being left behind there.
I don't want this hardcoded as I want to do so with other values back and forth.
Conditions to move values:
If a value has a certain neighbours
ie [1,0] neighbours are [0,0], [2,0], [0,1] and so on
so if it has a certain number of neighbours or doesn't I move it to either ' X ' or ' . '
This is so I can plot the coordinates with the corresponding label --> 'X' or '.'
I'm not sure if you're allowed to change the dictionary (this seems to be a homework assignment), but I think it would probably be better to store the coords as the keys and the symbols as the values of the dictionary.
# A dictionary comprehension to create a dict.
# Coords as the keys and '.' as the values.
board = {(x, y): '.' for x in range(10) for y in range(10)}
# To change the value just set some coords to 'X' or '.'.
board[(2, 3)] = 'X'
# Print the board.
for y in range(10):
for x in range(10):
print(board[(x, y)], end=' ')
print()
Maybe you could use tuples for internal lists and OrderedDict for external:
from collections import OrderedDict
dictionary = {'blue': OrderedDict.fromkeys([(0, 1), (0, 2)]),
'red': OrderedDict.fromkeys([(0, 3), (0, 4)])}
Then you could still iterate the values of the external dictionary one by one:
for pair in dictionary['blue']:
print(pair)
and inserting/deleting a pair would take O(1) on average.
Just a generic function to move values between keys. You should deal with the exception outside the function.
#! /usr/bin/env python
# -*- coding: utf-8 -*-
# vim:fenc=utf-8
def moveBetweenKeys(dictionary, src_key, dest_key, value):
"""
Move the value <value> from the key <src_key> to the key <dest_key>
Raises ValueError if the value was not found in the list of the keywork
<src_key>
"""
src_list = dictionary[src_key]
dest_list = dictionary[dest_key]
if value not in src_list:
raise ValueError("'%s' was not found in the list '%s'" % (value, src_key))
src_list.remove(value)
dest_list.append(value)
I have the following lists:
[[1, 5], [3, 7], [4, 2], [7, 8], [6, 3], [2, 5], [4, 1]]
And I am trying to sort them by the first value, after making the list go in ascending order:
Desired output:
[[1, 4], [1, 5], [2, 4], [2, 5], [3, 6], [3, 7], [7, 8]]
However, list.sort() only gives the following:
>>> mylist = [[1, 5], [3, 7], [4, 2], [7, 8], [6, 3], [2, 5], [4, 1]]
>>> mylist.sort()
>>> mylist
[[1, 5], [2, 5], [3, 7], [4, 1], [4, 2], [6, 3], [7, 8]]
>>>
Of course, I could always loop each list in the list of lists and sort it:
>>> mylist
[[1, 5], [2, 5], [3, 7], [4, 1], [4, 2], [6, 3], [7, 8]]
>>> for k in range(len(mylist)):
... mylist[k] = sorted(mylist[k])
...
>>> mylist
[[1, 5], [2, 5], [3, 7], [1, 4], [2, 4], [3, 6], [7, 8]]
>>> sorted(mylist)
[[1, 4], [1, 5], [2, 4], [2, 5], [3, 6], [3, 7], [7, 8]]
But is there a one liner to solve this?
You can do:
sorted(sorted(sublist) for sublist in mylist)
This is a little better than your loop:
for sublist in mylist:
sublist.sort()
mylist.sort()
Of course, this changes each sublist in-place. Judging by your examples, it looks like that is what you want, but I thought I should mention it just in case.
Here is a one liner that does the sort in-place
>>> mylist = [[1, 5], [3, 7], [4, 2], [7, 8], [6, 3], [2, 5], [4, 1]]
>>> mylist.sort(key=lambda x:x.sort() or x)
>>> mylist
[[1, 4], [1, 5], [2, 4], [2, 5], [3, 6], [3, 7], [7, 8]]
I am declaring multidimensional array in python
Nbrs[23][2] = [[1, 1], [1, 2], [2, 1],
[2, 3], [3, 2], [1, 3],
[3, 1], [1, 4], [3, 4],
[4, 3], [4, 1], [1, 5],
[2, 5], [3, 5], [4, 5],
[5, 4], [5, 3], [5, 2],
[5, 1], [1, 6], [5, 6],
[6, 5], [6, 1]
]
It gives me error as:
NameError: name 'Nbrs' is not defined
I cannot declare 2 dimensional array in python by this way?
Assignment statement:
Nbrs[23][2] = [[1, 1], [1, 2], [2
# ^ ^ you can't index Nbrs before it created
should be:
Nbrs = [[1, 1], [1, 2], [2
# now after this statement, Nbrs a list of list you can access
# its elements useng `Nbrs[i][j]` for i < len(Nbrs) and j < 2
I think you confuses because of C, C++ declarations!
You don't need to specify the dimensions when defining lists in python. When you type Nbrs[23][2] python is trying to find what's at [23][2] in Nbrs but in this case Nbrs doesn't exist because you are trying to define it for the first time here.
Instead do this:
Nbrs = [[1, 1], [1, 2], [2, 1], ....
That's not the right syntax. You don't need to include anything about the variable's type on the left-hand side; in particular, drop the dimensions.
Nbrs = [[1, 1], [1, 2], [2, 1], [2, 3], [3, 2], [1, 3], [3, 1], [1, 4], [3, 4], [4, 3], [4, 1], [1, 5], [2, 5], [3, 5], [4, 5], [5, 4], [5, 3], [5, 2], [5, 1], [1, 6], [5, 6], [6, 5], [6, 1]]
What you've written tries to assign to an element of Nbrs, which doesn't exist yet.