In [15]:
import numpy as np

a = np.array([-3, -2, 9, 1, -1])
b = np.array([11, 2, 3, 9, 5, 10, 4])

maskA = a > 0
maskB = (b  > 3) & (b < 9)

a[maskA] = 0

print(a)
print(b[maskB])

[-3 -2  0  0 -1]
[5 4]
In [21]:
import numpy as np
import numpy.typing as npt
 
def clean(a: npt.NDArray) -> npt.NDArray:
    """
    Replace all negative values in a with 0,
    then reverse the array in place and return it.
    """
    # Step 1: replace negatives with 0
    a[a < 0] = 0
    # Step 2: reverse the array *in place*
    # a[::-1] makes a reversed copy, so assign it back using slice on left
    a[:] = a[::-1]
    return a

clean(np.array([-1, 1,2,3,4]))
Out[21]:
array([4, 3, 2, 1, 0])
In [15]:
import matplotlib.pyplot as plt
import numpy as np

temps = np.array([-3, -2, 0, -5, -3, 2, 5, 4, 8, 11, 15, 13, 9, 12, 7, 4, 5, 6, 3, -1, 0, -2, -5, -11])
days = np.array(range(1,25)) # or use np.linspace(1,24,24)


freezing = temps < 0
cold = (temps < 10) & (temps >=0)
warm = temps >= 10

plt.plot(days, temps, label = "temperature fluctuations")

plt.plot(days[freezing], temps[freezing], 'bo', label = "freezing")
plt.plot(days[cold], temps[cold], 'go', label = "cold")
plt.plot(days[warm], temps[warm], 'ro', label = "warm")

plt.xlabel('Day')
plt.ylabel('Temperature')
plt.title('Temperatures over 24 Days')

plt.legend()
plt.show()
In [14]:
# plotting with pretty colors

import matplotlib.pyplot as plt
import numpy as np

temps = np.array([-3, -2, 0, -5, -3, 2, 5, 4, 8, 11, 15, 13, 9, 12, 7, 4, 5, 6, 3, -1, 0, -2, -5, -11])
days = np.array(range(1,25))


freezing = temps < 0
cold = (temps < 10) & (temps >=0)
warm = temps >= 10

plt.plot(days, temps, color = "lightskyblue", label = "temperature fluctuations")

plt.plot(days[freezing], temps[freezing], color = 'dodgerblue', marker = "o", linestyle = "none", label = "freezing")
plt.plot(days[cold], temps[cold], color = 'mediumslateblue', marker = "o", linestyle = "none", label = "cold")
plt.plot(days[warm], temps[warm], color = 'hotpink', marker = "o", linestyle = "none", label = "warm")


plt.xlabel('Day')
plt.ylabel('Temperature')
plt.title('Temperatures over 24 Days')

plt.legend()
plt.show()
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