Numpy: Drop rows with all nan or 0 values

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I'd like to drop all values from a table if the rows = nan or 0.

I know there's a way to do this using pandas i.e pandas.dropna(how = 'all') but I'd like a numpy method to remove rows with all nan or 0.

Is there an efficient implementation of this?

import numpy as np

a = np.array([
    [1, 0, 0],
    [0, np.nan, 0],
    [0, 0, 0],
    [np.nan, np.nan, np.nan],
    [2, 3, 4]
])

mask = np.all(np.isnan(a) | np.equal(a, 0), axis=1)
a[~mask]

NumPy: Remove all rows in a NumPy array that contain non , nan] [ 7. 8. 9.] [ 1. 0. 1.]] Remove all non-numeric elements of the said array [[ 1. 2. 3.]� Pandas treat None and NaN as essentially interchangeable for indicating missing or null values. In order to drop a null values from a dataframe, we used dropna() function this function drop Rows/Columns of datasets with Null values in different ways. Syntax: DataFrame.dropna(axis=0, how=’any’, thresh=None, subset=None, inplace=False) Parameters:

This will remove all rows which are all zeros, or all nans:

mask = np.all(np.isnan(arr), axis=1) | np.all(arr == 0, axis=1)
arr = arr[~mask]

And this will remove all rows which are all either zeros or nans:

mask = np.all(np.isnan(arr) | arr == 0, axis=1)
arr = arr[~mask]

NumPy: Remove nan values from a given array, 7. nan]] After removing nan values: [1. 2. 3. 0. 6. 7.] Pictorial Presentation: Python NumPy� Pandas DataFrame dropna () function is used to remove rows and columns with Null/NaN values. By default, this function returns a new DataFrame and the source DataFrame remains unchanged. We can create null values using None, pandas.NaT, and numpy.nan variables. The dropna () function syntax is:

In addition: if you want to drop rows if a row has a nan or 0 in any single value

a = np.array([
    [1, 0, 0],
    [1, 2, np.nan],
    [np.nan, np.nan, np.nan],
    [2, 3, 4]
])

mask = np.any(np.isnan(a) | np.equal(a, 0), axis=1)
a[~mask]

Output

array([[ 2.,  3.,  4.]])

Handling Missing Data, Common special values like NaN are not available for all data types. 0 * np. nan. Out[7]:. nan. Note that this means that aggregates over the values are well defined By default, dropna() will drop all rows in which any null value is present :. Step 2: Drop the Rows with NaN Values in Pandas DataFrame. To drop all the rows with the NaN values, you may use df.dropna(). Here is the complete Python code to drop those rows with the NaN values:

I like this approach

import numpy as np

arr = np.array([[ np.nan,  np.nan],
                [ -1.,  np.nan],
                [ np.nan,  -2.],
                [ np.nan,  np.nan],
                [ np.nan,   0.]])
mask = (np.nan_to_num(arr) != 0).any(axis=1)

Out:

>>> arr[mask]
... array([[ -1.,  nan],
          [ nan,  -2.]])

Pandas dropna() - Drop Null/NA Values from DataFrame, pandas as pd import numpy as np d1 drop all rows with any NaN and NaT values df1 = df.dropna() print(df1). Output: Name ID Salary Role 0 Pankaj 1� Drop missing value in Pandas python or Drop rows with NAN/NA in Pandas python can be achieved under multiple scenarios. Which is listed below. drop all rows that have any NaN (missing) values; drop only if entire row has NaN (missing) values; drop only if a row has more than 2 NaN (missing) values; drop NaN (missing) in a specific column

List comprehension can be used as a one liner.

>> a = array([65.36512 , 39.98848 , 28.25152 , 37.39968 , 59.32288 , 40.85184 ,
       71.98208 , 41.7152  , 33.71776 , 38.5504  , 21.34656 , 37.97504 ,
       57.5968  , 30.494656, 80.03776 , 33.94688 , 37.45792 , 27.617664,
       15.59296 , 27.329984, 45.2256  , 61.27872 , 57.8848  , 87.4592  ,
       34.29312 , 85.15776 , 46.37696 , 79.11616 ,       nan,       nan])

>> np.array([i for i in a if np.isnan(i)==False])

array([65.36512 , 39.98848 , 28.25152 , 37.39968 , 59.32288 , 40.85184 ,
       71.98208 , 41.7152  , 33.71776 , 38.5504  , 21.34656 , 37.97504 ,
       57.5968  , 30.494656, 80.03776 , 33.94688 , 37.45792 , 27.617664,
       15.59296 , 27.329984, 45.2256  , 61.27872 , 57.8848  , 87.4592  ,
       34.29312 , 85.15776 , 46.37696 , 79.11616 ])

pandas.DataFrame.dropna — pandas 1.1.0 documentation, Drop the rows where all elements are missing. >>> df.dropna(how='all') name toy born 0 Alfred NaN NaT 1 Batman Batmobile 1940-04-25 2 Catwoman� NumPy: Array Object Exercise-91 with Solution. Write a NumPy program to remove all rows in a NumPy array that contain non-numeric values. Pictorial Presentation:

how to delete nan values in python Code Example, Get code examples like "how to delete nan values in python" instantly right python by Cooperative Curlew on Mar 04 2020 Donate. 0 All Python Answers python � add colorbar matplotlib � add column using a list at poisition zero pandas� I have a (M x N) numpy array, which contains string values, numerical values and nans. I want to drop the rows which contain NaN values. I've tried: arr[~np.isnan(arr)] however i get the error:

Dealing with NaN, sensors = df.columns.values[1:] # all columns except the time column will be removed: df = df.drop(sensors, axis=1) print(df[:5]). time 0 06:00:00 1 06:15:00 2� Explanation: np.isnan(a) returns a similar array with True where NaN, False elsewhere. .any(axis=1) reduces an m*n array to n with an logical or operation on the whole rows, ~ inverts True/False and a[ ] chooses just the rows from the original array, which have True within the brackets.

How to drop empty rows from a Pandas dataframe in Python, DataFrame removes all rows that contain empty values. Use df.dropna() to drop rows with NaN from a Pandas dataframe column1 column2 0 a 0 2 c 2� Case 2: replace NaN values with zeros for a column using numpy. You can accomplish the same task of replacing the NaN values with zeros by using numpy: df['DataFrame Column'] = df['DataFrame Column'].replace(np.nan, 0) For our example, you can use the following code to perform the replacement:

Comments
  • The first one seemed like the best option.
  • Because I am unfamiliar with numpy I thought a[~foo] was an in-place delete operator. Jaime's post makes it clear that this creates a new array which you need to reassign.