50 lines
1 KiB
Python
50 lines
1 KiB
Python
|
def find_maxima(x):
|
||
|
|
"""Find local maxima of x.
|
||
|
|
|
||
|
|
Input arguments:
|
||
|
|
x -- 1D list of real numbers
|
||
|
|
|
||
|
|
Output:
|
||
|
|
idx -- list of indices of the local maxima in x
|
||
|
|
"""
|
||
|
|
|
||
|
|
maxima = []
|
||
|
|
|
||
|
|
len_x = len(x)
|
||
|
|
if len_x == 0:
|
||
|
|
return maxima
|
||
|
|
|
||
|
|
maxima = check_first_element(x, maxima)
|
||
|
|
maxima = check_last_element(x, maxima)
|
||
|
|
|
||
|
|
# Check numbers in between
|
||
|
|
i = 1
|
||
|
|
while i < len_x - 1:
|
||
|
|
if x[i] > x[i - 1]:
|
||
|
|
# We have found a potential maximum or start of a plateau
|
||
|
|
plateau_start = i
|
||
|
|
while i < len_x - 1 and x[i] == x[i + 1]:
|
||
|
|
i += 1
|
||
|
|
plateau_end = i
|
||
|
|
if x[plateau_end] > x[plateau_end + 1]:
|
||
|
|
maxima.append(plateau_start)
|
||
|
|
i += 1
|
||
|
|
return maxima
|
||
|
|
|
||
|
|
|
||
|
|
def check_first_element(x, maxima):
|
||
|
|
if x[0] > x[1]:
|
||
|
|
maxima.append(0)
|
||
|
|
return maxima
|
||
|
|
|
||
|
|
|
||
|
|
def check_last_element(x, maxima):
|
||
|
|
if x[-1] > x[-2]:
|
||
|
|
maxima.append(len(x) - 1)
|
||
|
|
return maxima
|
||
|
|
|
||
|
|
|
||
|
|
if __name__ == "__main__":
|
||
|
|
result = find_maxima([1, 2, 2, 1])
|
||
|
|
print(result)
|