Hands-On Geospatial Analysis with R and QGIS

apply

apply works on arrays or matrices and gives us an easier way to compute something row-wise or column-wise. For the apply() function, this row- or column-wise consideration is denoted by a margin. The apply() function takes the following form: apply(data, margin, function). This data has to be an array or a matrix, and the margin can be either 1 or 2, where 1 stands for a row-wise operation and 2 stands for a column-wise operation. We will work with the matrix all_prices, which has the following structure:

Here, we have a record of prices of three different items in three different months (January, March, and June), where a row represents ...