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 Python Data Type Q&A » numpy » List

### 1. Why NumPy instead of Python lists?    stackoverflow.com

Is it worth my learning NumPy? I have approximately 100 financial markets series, and I am going to create a cube array of 100x100x100 = 1 million cells. I will ...

### 2. Would you use numpy if you were just manipulating a list of binary binary values?    stackoverflow.com

Is there any advantage to using numpy when you're doing a large number of operations on lists of binary values? How about integers within a small range (like just the ...

### 3. Define dTypes in NumPy using a list?    stackoverflow.com

I just am having a problem with NumPy dtypes. Essentially I'm trying to create a table that looks like the following (and then save it using rec2csv):

``     ...``

### 4. Numpy vectorize, using lists as arguments    stackoverflow.com

The numpy `vectorize` function is useful, but it doesn't behave well when the function arguments are lists rather then scalars. As an example:

``````import numpy as np

def f(x, A):
...``````

### 5. increasing speed of python list operations and comparisons in a custom table class    stackoverflow.com

so, I'm using the following class to create a table and I need to find a way to not only make it faster but make interactions with it faster

``````class Table(object):
...``````

### 6. Python: Get item from list based on input    stackoverflow.com

I appreciate this may not be directly possible so I would be interested how you would go about solving this problem for a general case. I have a list item that looks ...

### 7. fastest way to arrange data in python numpy based on list    stackoverflow.com

I have problem in arrange data in numpy example a have list of data range :

``````numpy.array([1,3,5,4,6])
``````
and I have data :
``````numpy.array([1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19])
``````
and I need the data to be arrange to
``````numpy.array([

[1,9999,9999,9999,9999,9999,9999]

[2,3,4,9999,9999,9999]

[5,6,7,8,9,9999]

[10,11,12,13,9999,9999]

[14,15,16,17,18,19]

])
``````
I thought it's a ...

### 8. Numpy.Array in Python list?    stackoverflow.com

I've got a list (used as a stack) of numpy arrays. Now I want to check if an array is already in the list. Had it been tuples for instance, I ...

### 9. Boost.python overloaded constructor for numpy array and python list    stackoverflow.com

Given a C++ class exposed with Boost.Python, how do I expose two constructors:

• one that takes a numpy array, and
• another that takes a python list?

### 10. Check if numpy array present in list    stackoverflow.com

Possible Duplicate:
Numpy.Array in Python list?
If I have a list of `numpy.array`s like this
``````a = [ numpy.array([1,2]), numpy.array([2, 3]), numpy.array([12,155])]
``````
how can I check if specified ...

### 11. How to save a list as numpy array in python?    stackoverflow.com

I need to know if it is possible to save a python list as a numPy array.

### 12. Merging a list of numpy arrays into one array (fast)    stackoverflow.com

what would be the fastest way to merge a list of numpy arrays into one array if one knows the length of the list and the size of the arrays, which ...

### 13. Is it possible to use numpy.argmax with a custom field of objects in a list?    stackoverflow.com

Something like:

``````class Test:
def __init__(self, n):
self.id = n

def __str__(self):
...``````

### 14. Create a python class that is treated as a list, but with more features?    stackoverflow.com

I have a class called dataList. It is basically a list with some metadata---myDataList.data contains the (numpy) list itself, myDataList.tag contains a description, etc. I would like to be able to ...

### 15. How to create a dynamic array    stackoverflow.com

As I know, list type in Python is a dynamic pointer array, which will increase it's capacity when items are appended to it. And array in NumPy uses a continuous memory ...

### 16. How to compute the similarity between lists of features?    stackoverflow.com

I have users and resources. Each resource is described by a set of features and each user is related to a different set of resources. In my particular case, the resources ...

### 17. Python List of np arrays to array    stackoverflow.com

I'm trying to turn a list of 2d numpy arrays into a 2d numpy array. For example,

``````dat_list = []
for i in range(10):
dat_list.append(np.zeros([5, 10]))
``````
What I would ...

### 18. Flatten list of lists in Python with non-iterable types?    stackoverflow.com

Possible Duplicate:
Flatten (an irregular) list of lists in Python
I've seen quite a few 'How to flatten list of lists' questions on SO, but I'm ...

### 19. How Do I create a list from numpy array?    stackoverflow.com

How do I get numpy array into python list? looking for ('foo', 1, 2, 3, 4) series is a numpy array

``````symbol = 'foo'

def rowp (symbol,series):
...``````

### 20. Splitting arrays python    stackoverflow.com

I have a 2D array in Python either a normal one or a numpy array with dimensions (150, 5), I wish to split it into two arrays of dimensions (150, 3) ...

### 21. Average duplicate values from two paired lists in Python using NumPy    stackoverflow.com

In the past I have faced myself dealing with averaging two paired lists and I have used the answers provided there successfully. However with large (more than 20,000) items the procedure ...

### 22. Python: Split numpy array    stackoverflow.com

I have an array produced by numpy which looks as follows:

[ 54.51399994 -12.10200024 -11.88099957]
[ 56.23899841 -8.30799961 -2.03500009]
How do i convert this to a list? ...

### 23. Calculating Correlation Coefficient with Numpy    stackoverflow.com

I have a list of values and a 1-d numpy array, and I would like to calculate the correlation coefficient using `numpy.corrcoef(x,y,rowvar=0)`. I get the following error:

``````Traceback (most recent call last):
File ...``````

### 24. Numpy array to list    python-forum.org

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