Summary
This chapter informed us about a great number of common NumPy functions. We read a file with loadtxt and wrote to a file with savetxt. We made an identity matrix with the eye function. We read a CSV file containing stock quotes with the loadtxt function. The NumPy average and mean functions allow one to calculate the weighted average and arithmetic mean of a data set.
A few common statistics functions were also mentioned – first, the min and max functions that we used to determine the range of the stock prices; second, the median function that gives the median of a data set; and finally, the std and var functions that return the standard deviation and variance of a set of numbers.
We calculated the simple stock returns with the diff function that returns back the differences between sequential elements. The log function computes the natural logarithms of array elements.
By default, loadtxt tries to convert all data into floats. The loadtxt function has a special parameter for this purpose...
