Basic plotting

In order to plot the data we use the matplotlib package. This can be loaded by using the following command:

import matplotlib.pyplot as plt

however, this should have already been done when loading the pycrtools. Besides the plotting commands provided by matplotlib, this plotting functionality is also available from the hArrays.

Matplotlib

Depending on the system you are working on, you may have to create a window in which the plots are shown. This is done by:

plt.show()

Now we can use the following plotting commands to show the average spectra for two antennas:

frequencies = datafile["FREQUENCY_DATA"].setUnit("M", "")
plt.subplot(1, 2, 1)
plt.title("Average spectrum for two antennas")
plt.xlabel(frequencies.getKey("name") + " [" + frequencies.getUnit() + "]")
plt.ylabel(avspectrum.getKey("name") + " [" + avspectrum.getUnit() + "]")
for i in range(2):
    plt.semilogy(frequencies.vec(), avspectrum[i].vec())

Note that the array entries need to be converted to vectors, using the vec() method, when they are given as arguments to the plotting command.

To plot the time series of a section of the dataset, we first read in the samples from all antennas:

datafile["BLOCK"] = 2
datafile["BLOCKSIZE"] = 2 ** 16
timeall = datafile["TIME_DATA"]
timeall.setUnit("m", "s")
fxall = datafile["TIMESERIES_DATA"]

and then we plot it:

plt.subplot(1, 2, 2)
plt.title("Time series of antenna 0")
plt.plot(timeall.vec(), fxall[0].vec())
plt.xlabel(timeall.getKey("name") + " [" + timeall.getUnit() + "]")
plt.ylabel("Electric Field [ADC counts]")

The results of the above is shown below.

(Source code)

If you want to plot a linear plot use plt.plot(), for a loglog plot you use plt.loglog() and for a log-linear plot you can use plt.semilogx() or plt.semilogy(), depending on which axis needs to be logarithmic.

Plotting using the hArray plotting methods

Another way of producing plots is to use the plot method of the hArray class:

avspectrum.par.xvalues = frequencies
avspectrum.par.title = "Average spectrum"
avspectrum[0].plot(logplot="y", clf=True)

(Source code)

This creates a semilog-plot with appropriate labels and units (if provided beforehand).

You can either provide the parameters directly (has precedence), or set the plotting parameters and attributes to the par class of the array, e.g.:

>>> array.par.xvalues = x_vector
>>> array.plot()

If the array is in looping mode, multiple curves are plotted in a single window. Hence,:

>>> avspectrum.par.logplot = "y"
>>> avspectrum[...].plot(legend=datafile.antennas)

will simply plot all spectra of all antennas (= highest array index) in the array.

The available parameters, used in the hArray.par class, are:

xvalues	An array with corresponding x values. If None, integer numbers from 0 to the length of the array are used.
xlabel	The x-axis label. If not specified, use the name keyword of the array. Units are added automatically.
ylabel	The y-axis label. If not specified, use the name keyword of the array. Units are added automatically.
xlim	Tuple with minimum and maximum values for the x-axis.
ylim	Tuple with minimum and maximum values for the y-axis.
title	A title for the plot
clf	If True (default) clear the screen before plotting. If False plots are composed with multiple lines from different arrays.
logplot	Can be used to make log-log or semi-log plots: “x” -> semilog plot in x “y” -> semilog plot in y “xy” -> loglog plot