Count and summation of positive and negative number sequences

Question

I want to write a code to count and sum any positive and negative series of numbers.
Numbers are either positive or negative(no zero).
I have written codes with for loops. Is there any creative alternative?

Data

R

set.seed(100) x <- round(rnorm(20, sd = 0.02), 3) 

python

x = [-0.01, 0.003, -0.002, 0.018, 0.002, 0.006, -0.012, 0.014, -0.017, -0.007,       0.002, 0.002, -0.004, 0.015, 0.002, -0.001, -0.008, 0.01, -0.018, 0.046] 

loops

R

sign_indicator <- ifelse(x > 0, 1,-1) number_of_sequence <- rep(NA, 20) n <- 1 for (i in 2:20) {   if (sign_indicator[i] == sign_indicator[i - 1]) {     n <- n + 1   } else{     n <- 1   }   number_of_sequence[i] <- n    } number_of_sequence[1] <- 1  #############################  summation <- rep(NA, 20)  for (i in 1:20) {   summation[i] <- sum(x[i:(i + 1 - number_of_sequence[i])]) } 

python

sign_indicator = [1 if i > 0 else -1 for i in X]  number_of_sequence = [1] N = 1 for i in range(1, len(sign_indicator)):     if sign_indicator[i] == sign_indicator[i - 1]:         N += 1     else:         N = 1     number_of_sequence.append(N)  ############################# summation = []  for i in range(len(X)):     if number_of_sequence[i] == 1:                     summation.append(X[i])      else:         summation.append(sum(X[(i + 1 - number_of_sequence[i]):(i + 1)])) 

result

        x n_of_sequence    sum 1  -0.010             1 -0.010 2   0.003             1  0.003 3  -0.002             1 -0.002 4   0.018             1  0.018 5   0.002             2  0.020 6   0.006             3  0.026 7  -0.012             1 -0.012 8   0.014             1  0.014 9  -0.017             1 -0.017 10 -0.007             2 -0.024 11  0.002             1  0.002 12  0.002             2  0.004 13 -0.004             1 -0.004 14  0.015             1  0.015 15  0.002             2  0.017 16 -0.001             1 -0.001 17 -0.008             2 -0.009 18  0.010             1  0.010 19 -0.018             1 -0.018 20  0.046             1  0.046 

Answer 1

The other solutions look okay but you don't really need to use sophisticated language features or library functions for this simple problem.

result, prev = [], None  for idx, cur in enumerate(x):     if not prev or (prev > 0) != (cur > 0):         n, summation = 1, cur     else:         n, summation = n + 1, summation + cur     result.append((idx, cur, n, summation))     prev = cur 

As you can see, you don't really need sign_indicator list, two for-loops or range function as in the snippet in the question section.

If you want index to start from 1, use enumerate(x, 1) instead of enumerate(x)

To see the result, you can run the following code

for idx, num, length, summation in result:      print(f"{idx:>2d} {num:.3f} {length:>2d} {summation:.3f}")