Category: Python Answers

Sometimes, we want to find local maxima or minima with Numpy in a 1D Numpy array with Python.

In this article, we’ll look at how to find local maxima or minima with Numpy in a 1D Numpy array with Python.

How to find local maxima or minima with Numpy in a 1D Numpy array with Python?

To find local maxima or minima with Numpy in a 1D Numpy array with Python, we can use the argrelextrema methods.

For instance, we write

import numpy as np
from scipy.signal import argrelextrema

x = np.random.random(12)

argrelextrema(x, np.greater)
argrelextrema(x, np.less)

to create a NumPy array with

x = np.random.random(12)

Then we find the local maxima of array x by calling argrelextrema with x and np.greater.

Likewise, we find the local minima of array x by calling argrelextrema with x and np.less.

Conclusion

To find local maxima or minima with Numpy in a 1D Numpy array with Python, we can use the argrelextrema methods.

Sometimes, we want to set Matplotlib color bar size to match graph with Python.

In this article, we’ll look at how to set Matplotlib color bar size to match graph with Python.

How to set Matplotlib color bar size to match graph with Python?

To set Matplotlib color bar size to match graph with Python, we can use the make_axes_locatable function.

For instance, we write

import matplotlib.pyplot as plt
from mpl_toolkits.axes_grid1 import make_axes_locatable
import numpy as np
    
plt.figure()
ax = plt.gca()
im = ax.imshow(np.arange(100).reshape((10,10)))
    
divider = make_axes_locatable(ax)
cax = divider.append_axes("right", size="5%", pad=0.05)
   
plt.colorbar(im, cax=cax)

to call make_axes_locatable to create an axes on the right side of ax.

Then we call append_axes with 'right' to append axes to the right of the graph.

Also, we set the width of the axis to 5% by setting the size to '5%'.

And we add 0.05 inch of padding by setting pad to 0.05.

Conclusion

To set Matplotlib color bar size to match graph with Python, we can use the make_axes_locatable function.

Sometimes, we want to round up a number with Python.

In this article, we’ll look at how to round up a number with Python.

How to round up a number with Python?

To round up a number with Python, we can use the math.ceil method.

For instance, we write

import math

print(int(math.ceil(4.2)))

to call math.ceil with a number to round it up.

Then we call int to convert the rounded up number to an integer.

Conclusion

To round up a number with Python, we can use the math.ceil method.

Sometimes, we want to join list of lists in Python.

In this article, we’ll look at how to join list of lists in Python.

How to join list of lists in Python?

To join list of lists in Python, we can use the itertools.chain.from-_iterable method.

For instance, we write

import itertools

a = [['a','b'], ['c']]
print(list(itertools.chain.from_iterable(a)))

to call itertools.chain.from_iterable with a to combine the lists in the list a into one flattened iterator and return it.

Then we call list to convert the iterator into a list.

Conclusion

To join list of lists in Python, we can use the itertools.chain.from-_iterable method.

Sometimes, we want to calculate the date six months from the current date using the datetime Python module.

In this article, we’ll look at how to calculate the date six months from the current date using the datetime Python module.

How to calculate the date six months from the current date using the datetime Python module?

To calculate the date six months from the current date using the datetime Python module, we can use the dateutil package.

To install it, we run

pip install python-dateutil

Then we use it by writing

from datetime import date
from dateutil.relativedelta import relativedelta

six_months = date.today() + relativedelta(months=+6)

to add today’s date to the time delta 6 months from now.

We get today’s date with date.today().

And we get the time delta 6 months after with relativedelta(months=+6).

And we add them together to get the date 6 months from now.

Conclusion

To calculate the date six months from the current date using the datetime Python module, we can use the dateutil package.