Pandas: Subtracting two date columns and the result being an integer
I have two columns in a Pandas data frame that are dates.
numpy
Concatenate two NumPy arrays vertically
I tried the following:
Convolve2d just by using Numpy
I am studying image-processing using Numpy and facing a problem with filtering with convolution.
Comparing previous row values in Pandas DataFrame
import pandas as pd data={'col1':[1,3,3,1,2,3,2,2]} df=pd.DataFrame(data,columns=['col1']) print df col1 0 1 1 3 2 3 3 1 4 2 5 3 6 2 7 2 I have the following Pandas DataFrame and I want to create another column that compares the previous row of col1 to see if they are equal. What would be the … Read more
Most efficient way to forward-fill NaN values in numpy array
Example Problem As a simple example, consider the numpy array arr as defined below: import numpy as np arr = np.array([[5, np.nan, np.nan, 7, 2], [3, np.nan, 1, 8, np.nan], [4, 9, 6, np.nan, np.nan]]) where arr looks like this in console output: array([[ 5., nan, nan, 7., 2.], [ 3., nan, 1., 8., nan], … Read more
Numpy ValueError: setting an array element with a sequence. This message may appear without the existing of a sequence?
Why do I get this error message? ValueError: setting an array element with a sequence. Thank you
Convert structured array to regular NumPy array
The answer will be very obvious I think, but I don’t see it at the moment.
Find nearest indices for one array against all values in another array – Python / NumPy
I have a list of complex numbers for which I want to find the closest value in another list of complex numbers.
scipy: savefig without frames, axes, only content
In numpy/scipy I have an image stored in an array. I can display it, I want to save it using savefig without any borders, axes, labels, titles,… Just pure image, nothing else.
shuffling/permutating a DataFrame in pandas
What’s a simple and efficient way to shuffle a dataframe in pandas, by rows or by columns? I.e. how to write a function shuffle(df, n, axis=0) that takes a dataframe, a number of shuffles n, and an axis (axis=0 is rows, axis=1 is columns) and returns a copy of the dataframe that has been shuffled n times.