By creating and specifying names for the different figure windows and subplots within them, you access the different plot windows more efficiently. Alternatively, setting one or both of them equal to an array that has the same length as the x and y arrays allows you to give each data point an error bar with a different value. Additionally if you want pretty looking ticks you can use matplotlib. The two important ones here are plot and errorbar , which make regular plots and plots with error bars, respectively. It is important to understand that MatPlotLib draws straight lines between data points. The two curves cross each other at the points where. When error bars are desired, you typically replace the plot function with the errorbar function. Both vertical and horizontal error bars can be displayed.

Notice that regardless of the specified line style, Matplotlib insists on making negative contours dashed as long as a single color is specified! The figure below illustrating Mulitple plots in the same window is produced by the following code: We have more to say about the errorbar function in the sections on logarithmic plots. If we plot counts per second as a function of time on a normal plot, as we have done in the plot on the left below, then the count rate is indistinguishable from zero after about days. You can think of it as the plot function lifting the pen that is drawing the line in the plot when it comes to the masked points in the array ytanM. In fact we can use the figure function to open up multiple figure objects with different figure windows. The plot now looks much more like the familiar function we know. Matplotlib honors the NumPy conventions for masked arrays, in that masked regions of two-dimensional plots are omitted.

By default, the plot function draws a line between the data points that were entered. We have also include a call to the axline function to create an axis.

As we shall see, we can instruct the function plot either to just draw point—or dots—at each data point, or we can instruct it to draw straight lines between the data points. Other matplltlib for plt.


Line 13 specifies that the plotting commands that follow will be act on the first box. This is a convenience function that adjusts the sizes of the plots to make room for the axes labels. The two curves cross each other matplotilb the points where. Our code consists of four parts import the NumPy and MatPlotLib modules lines below create the data arrays lines matpkotlib have plot draw straight lines between the data points line 5 below display the plot in a figure window using the show function line 6 below Here is our lohlog, which consists of only 6 lines: The first two lines import respectively the numpy and matplotlib pyplot modules.

The next two lines define the arrays x and y which we want to plot against each other. To see how this works, type the following code into a Python module and run it:. Figures with multiple plots lotlog be created using the subplot command. Alternatively, the loc argument may be omitted and Matplotlib puts the legend where it sees fit.

Strings, Lists, Arrays, and Dictionaries 4. This command has three arguments, the number of rows of plots in the figure, the number of columns, and the particular plot being created next:. Vector plots can also be made in Matplotlib. An interactive session with pyplot 5.

All of your fitted lines should plkt behind the data.

5. Plotting — PyMan documentation

The plot below shows an example of such a plot. If the space between data points is too large, the matplotlb lines the plot function draws between data points will be visible.

In fact we can use the figure function to open up multiple logglog objects with different figure windows. The latest source code can also be downloaded here. For data sets that vary exponentially in the independent variable, it is often useful to use one or more logarithmic axes.

A simple plot of a sine function.

Chapter 4 Graphics with Matplotlib

In this plot, we label the and axes, create a legend, and draw lines to indicate where and are zero. The annotate command connects text with plot points by an arrow. However, this procedure can on occasion backfire, resulting in strange plotting behavior. But the brief introduction given here should suffice for making most plots not involving logarithmic axes.


The plot below was created using the same program shown above but with data points instead of The quiver command produces vector plots from two-dimensional arrays u and v in this case containing lolog vector component values. Matp,otlib care to follow the exact syntax.

Technically, before issuing any plotting commands, the figure command must be issued. You just use one or the other depending on which axis you want to be logarithmic. You can save this plot to an image file by clicking on the floppy disk icon at the top of the plot window. It would be nice to exclude that line. If a line type is chosen, the lines lloglog drawn between the data points.

Often you want to create two matplotljb more graphs and place them next to one another, generally because they are related to each other in some way. Torres Sep time s position m uncertainty m 0.

Use the data in the dy column as the error estimates for the data. Calls to most pyplot functions return stuff that can sometimes be used in subsequent functions. Here we demonstrate methods for doing this. The resulting plot is shown in figure 4. No screen output is produced before this function is called. The rwidth option specifies the width of the histogram bars relative to the bin size, with a default of 1. Examples are given following the two tables.

Colormaps provided by Matplotlib include autumnbonecoolcopperflaggrayhothsvjetpinkprismspringsummerwinterand spectral and each has its associated function call.

The right-most icon pops up a window which allows you to specify an output matllotlib for the plot.