Time for action – enveloping with Bollinger Bands

We already know how to calculate the SMA. So, if you need to refresh your memory, please review the Time for action – computing the simple average section in this chapter. This example will introduce the NumPy fill() function. The fill() function sets the value of an array to a scalar value. The function should be faster than array.flat = scalar or setting the values of the array one-by-one in a loop. Perform the following steps to envelope with the Bollinger Bands:

1. Starting with an array called sma that contains the moving average values, we will loop through all the datasets corresponding to those values. After forming the dataset, calculate the standard deviation. Note that at a certain point, it will be necessary to calculate the difference between each data point and the corresponding average value. If we do not have NumPy, we will loop through these points and subtract each of the values one-by-one from the corresponding average. However...