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When I print a numpy array, I get a truncated representation, but I want the full array. >>> numpy.arange(10000) array([ 0, 1, 2, ..., 9997, 9998, 9999]) >>> numpy.arange(...
kame's user avatar
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827 votes
13 answers
1.4m views

How do I dump a 2D NumPy array into a csv file in a human-readable format?
Dexter's user avatar
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718 votes
17 answers
1.7m views

How do I convert a Pandas dataframe into a NumPy array? import numpy as np import pandas as pd df = pd.DataFrame( { 'A': [np.nan, np.nan, np.nan, 0.1, 0.1, 0.1, 0.1], 'B': [0.2, ...
Mister Nobody's user avatar
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695 votes
12 answers
727k views

A 2D array can be reshaped into a 1D array using .reshape(-1). For example: >>> a = numpy.array([[1, 2, 3, 4], [5, 6, 7, 8]]) >>> a.reshape(-1) array([[1, 2, 3, 4, 5, 6, 7, 8]]) ...
user2262504's user avatar
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678 votes
32 answers
1.2m views

How do I count the number of 0s and 1s in the following array? y = np.array([0, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 1]) y.count(0) gives: numpy.ndarray object has no attribute count
mflowww's user avatar
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598 votes
14 answers
837k views

df = pd.read_csv('somefile.csv') ...gives an error: .../site-packages/pandas/io/parsers.py:1130: DtypeWarning: Columns (4,5,7,16) have mixed types. Specify dtype option on import or set low_memory=...
Josh's user avatar
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580 votes
14 answers
1.3m views

Is there a direct way to import the contents of a CSV file into a record array, just like how R's read.table(), read.delim(), and read.csv() import data into R dataframes? Or should I use csv.reader() ...
hatmatrix's user avatar
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520 votes
16 answers
566k views

How do I sort a NumPy array by its nth column? For example, given: a = array([[9, 2, 3], [4, 5, 6], [7, 0, 5]]) I want to sort the rows of a by the second column to obtain: ...
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510 votes
15 answers
870k views

How do I add a color column to the following dataframe so that color='green' if Set == 'Z', and color='red' otherwise? Type Set 1 A Z 2 B Z 3 B X 4 C Y
user7289's user avatar
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499 votes
21 answers
630k views

How do I find the nearest value in a numpy array? Example: np.find_nearest(array, value)
Fookatchu's user avatar
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494 votes
14 answers
674k views

How do I print formatted NumPy arrays in a way similar to this: x = 1.23456 print('%.3f' % x) If I want to print the numpy.ndarray of floats, it prints several decimals, often in 'scientific' format, ...
camillio's user avatar
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480 votes
17 answers
595k views

After creating a NumPy array, and saving it as a Django context variable, I receive the following error when loading the webpage: array([ 0, 239, 479, 717, 952, 1192, 1432, 1667], dtype=int64) ...
Karnivaurus's user avatar
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465 votes
9 answers
807k views

What is the simplest way to compare two NumPy arrays for equality (where equality is defined as: A = B iff for all indices i: A[i] == B[i])? Simply using == gives me a boolean array: >>> ...
clstaudt's user avatar
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460 votes
4 answers
146k views

import numpy as np y = np.array(((1,2,3),(4,5,6),(7,8,9))) OUTPUT: print(y.flatten()) [1 2 3 4 5 6 7 8 9] print(y.ravel()) [1 2 3 4 5 6 7 8 9] Both function return the ...
cryptomanic's user avatar
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450 votes
10 answers
1.1m views

How do I get the dimensions of an array? For instance, this is 2x2: a = np.array([[1, 2], [3, 4]])
Cristi P's user avatar
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447 votes
24 answers
1.0m views

I have a matrix in the type of a Numpy array. How would I write it to disk it as an image? Any format works (png, jpeg, bmp...). One important constraint is that PIL is not present.
M456's user avatar
  • 5,857
444 votes
7 answers
719k views

How do I convert a NumPy array into a Python List?
Alex Brooks's user avatar
  • 5,453
432 votes
3 answers
278k views

I am trying to implement a "Digit Recognition OCR" in OpenCV-Python (cv2). It is just for learning purposes. I would like to learn both KNearest and SVM features in OpenCV. I have 100 samples (i.e. ...
Abid Rahman K's user avatar
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421 votes
11 answers
1.9m views

Let x be a NumPy array. The following: (x > 1) and (x < 3) Gives the error message: ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all() How ...
Homunculus Reticulli's user avatar
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405 votes
17 answers
588k views

How do I efficiently obtain the frequency count for each unique value in a NumPy array? >>> x = np.array([1,1,1,2,2,2,5,25,1,1]) >>> freq_count(x) [(1, 5), (2, 3), (5, 1), (25, 1)]
Abe's user avatar
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402 votes
10 answers
588k views

How do I drop nan, inf, and -inf values from a DataFrame without resetting mode.use_inf_as_null? Can I tell dropna to include inf in its definition of missing values so that the following works? df....
user avatar
396 votes
13 answers
510k views

If I have a numpy dtype, how do I automatically convert it to its closest python data type? For example, numpy.float32 -> "python float" numpy.float64 -> "python float" numpy.uint32 -> "...
conradlee's user avatar
  • 13.9k
391 votes
17 answers
763k views

How can I check which version of NumPy I'm using?
larus's user avatar
  • 4,587
379 votes
8 answers
202k views

How does np.einsum work? Given arrays A and B, their matrix multiplication followed by transpose is computed using (A @ B).T, or equivalently, using: np.einsum("ij, jk -> ki", A, B)
Lance Strait's user avatar
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374 votes
27 answers
446k views

I have a pandas dataframe in which one column of text strings contains comma-separated values. I want to split each CSV field and create a new row per entry (assume that CSV are clean and need only be ...
Vincent's user avatar
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