Linked Questions
19 questions linked to/from A fast way to find the largest N elements in an numpy array
2
votes
1
answer
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Is there a numpy limited argsort? [duplicate]
I have an array with 1M floats and want to get the top 10. Wondering if there's an argsort that will only give top 10 to speed things up. I suppose I could do np.argmax() 10 times, dropping the ...
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836
votes
21
answers
810k
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How do I get indices of N maximum values in a NumPy array?
NumPy proposes a way to get the index of the maximum value of an array via np.argmax.
I would like a similar thing, but returning the indexes of the N maximum values.
For instance, if I have an array, ...
- 11.3k
8
votes
2
answers
8k
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N largest values in each row of ndarray
I have an ndarray where each row is a separate histogram. For each row, I wish to find the top N values.
I am aware of a solution for the global top N values (A fast way to find the largest N ...
- 1,901
3
votes
3
answers
14k
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How to get indices of top-K values from a numpy array
Let suppose I have probabilities from a Pytorch or Keras predictions and result is with the softmax function
from scipy.special import softmax
probs = softmax(np.random.randn(20,10),1) # 20 instances ...
- 4,292
5
votes
1
answer
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how to get the index of the largest n values in a multi-dimensional numpy array [duplicate]
I want to get the index of the largest n values in a multi-dimensional numpy array. For get the index of the largest n values in a one-dimensional numpy array, i found this. After test in interactive ...
- 6,545
0
votes
4
answers
4k
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More Efficient Way to find the Second Largest Item in a List in Python
I wrote this simple code for a simple task of finding the second largest item in a list of integers:
def second_largest(input_list):
input_list.sort()
return input_list[-2]
However, for large ...
3
votes
3
answers
2k
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Getting n-th ranked column IDs per row of a dataframe - Python/Pandas
I am trying to find a method for finding the nth ranked value and returning the column name. So for example, given a data-frame:
df = pd.DataFrame(np.random.randn(5, 4), columns = list('ABCD'))
# ...
- 2,690
2
votes
3
answers
1k
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Find indices of x minimum values of a list
I have a list of length n.
I want to find the indices that hold the 5 minimum values of this list.
I know how to find the index holding the minimum value using operator
min_index,min_value = min(...
- 123
6
votes
1
answer
1k
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Numpy's partition slower than sort for small arrays
I was looking for an efficient way to calculate the nth largest value in a numpy array and this answer lead me to np.partition.
By the way, I have noticed that the naive sorting is faster than np....
- 7,546
0
votes
2
answers
3k
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Python, Numpy, replacing second max value with 1, others with 0
exploring the Internet doesn't give me any results with my problem. I have array like this:
y= [[ 2.63321579e-16 9.99986649e-01 2.90973702e-32 9.93230242e-06
1.56965105e-30 1....
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6
votes
3
answers
937
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m Smallest values from upper triangular matrix with their indices as a list of tuples
I have a np.ndarray as follows:
[[ inf 1. 3. 2. 1.]
[ inf inf 2. 3. 2.]
[ inf inf inf 5. 4.]
[ inf inf inf inf 1.]
[ inf inf inf inf inf]]
Is there a way to get the ...
- 755
0
votes
4
answers
705
views
How to identify row and column based on top-K values in Pandas data frame
I have a data frame created this way:
import pandas as pd
d = {'gene' : ['foo', 'qux', 'bar', 'bin'],
'one' : [1., 2., 3., 1.],
'two' : [4., 3., 2., 1.],
'three' : [1., 2., 20., 1.],
...
- 64.5k
1
vote
2
answers
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Time complexity of torch.topk
When m and n of n.topk(m) exceed 20 million and 200,000 respectively, the sorting becomes very slow(over 3 hours). I want to know the time complexity of torch.topk and improvement measures of the ...
- 11
0
votes
2
answers
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Calculating Euclidean distance with a lot of pairs of points is too slow in Python
The main goal is to generate the customer similarity based on Euclidean distance, and find the 5 most similar customers for each customer.
I have 400,000 customers data, each of them has 40 attributes....
- 133
0
votes
1
answer
824
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NumPy: finding N largest elements in a matrix [duplicate]
Edited since my last question was a duplicate, but I'm struggling with this as well. I'm currently working with a matrix and can easily find the largest element with
M[M != 1].max()
However, I'm ...
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