I have few weeks data with units sold given

```py
xs[weeks] = [1,2,3,4]
ys['Units Sold'] = [1043,6582,5452,7571]

```

from the given series, we can see that although there is a drop from xs[2] to xs[3] but overall the trend is increasing. How to detect the trend in small time series dataset.

Is finding a slope for the line is the best way? And how to calculate slope angle of a line in python?