Python Tutorial: Legends, annotations, & styles

Key Takeaways

let's look at a few more tricks to make BOTS fancier legends are useful when several kinds of plots or curves are displayed on the same axis a legend is a box with labels to help readers distinguish distinct features here the famous irish data set is plotted showing the sepal width versus the sepal length for three species of flour setosa versicolor and virginica here are some code that generates the previous plot notice that each scatter plot is given a label to use in the legend and the legend is created with the legend command the keyword argument loke loc specifies where to put the legend the location of the legend can be given as a specific string like lower left or using an equivalent integer code it's usually easier to remember the string than the numeric location code even if it's more of our boasts the annotate function adds text to a figure it can also draw arrows from the text to some other features to highlight there are flexible ways to specify coordinates in the API there's also a keyword argument arrow props that uses a Python dictionary to customize the arrow that's drawn let's avoid the legends this time and place text labels on the plot directly with the annotate function we'll place directly at locations given by the tuple X Y in each invocation this is the resulting figure the annotate function requires at least the string argument s for the text to draw the keyword argument XY tells the point being annotated if we also want to draw an arrow we need to specify the coordinates XY text of the text and the point being annotated to draw the arrow the keyword arrow props needs to be specified by a dictionary with the arrows properties and here's the same figure this time drawing arrows from the text labels to the points being annotated this is the required code notice the specification of coordinates X Y and x/y text in the calls to annotate it usually takes some experimentation to get the coordinates to make a visually pleasing plot the dictionary arrow props is required to make the arrow appear finally we should know that the default plot styles are controlled by style sheets in matplotlib the style sheets controlled default fonts line widths color palettes backgrounds and more we can switch between global style sheets using style use and we can find out what styles we can use with style available for instance here's a sample of our plot created with the GG plot style sheet and here's the same plot drawn using the 538 style sheet now it's your turn to practice working with legends annotations and plot styles