Python/C2/Other-types-of-plots/English-timed
From Script | Spoken-Tutorial
Time | Narration |
00:01 | Hello Friends and welcome to the tutorial on Other types of plots |
00:06 | Till now we have seen only one kind of plotting. |
00:10 | Hence in this tutorial we will be looking at some more kinds of plots. |
00:16 | At the end of this tutorial, you will be able to
Create scatter plot Create pie charts Create bar charts Create log-log plots Use the matplotlib help |
00:29 | So let us begin with scatter plot |
00:33 | Before beginning this tutorial,we would suggest you to complete the tutorial on "Loading data from files" and "Plotting data". |
00:42 | In a scatter plot, the data is displayed as a collection of points, where each point determines it's position on the horizontal axis and the vertical axis respectively. |
00:54 | This kind of plot is also called a scatter chart, a scatter diagram or a scatter graph. |
01:01 | Before we proceed further , start your IPython interpreter |
01:06 | So type ipython hypen pylab |
01:13 | Plot a scatter plot showing the percentage profit of a company A from the year 2000-2010. |
01:22 | The data for the same is available in the file company-a-data.txt. |
01:33 | Type cat space slash home slash fossee slash other-plot slash company-a-data.txt (enter) |
01:50 | The data file has two lines with a set of values in each line, the first line representing years and the second line representing the profit percentages. |
02:02 | To produce the scatter plot, we first need to load the data from the file using loadtxt command. |
02:10 | Type year,profit = loadtxt within bracket in single quote slash home slash fossee slash other-plot slash company-a-data.txt comma dtype=type in bracket int()closing brackets hit enter |
02:52 | By default loadtxt converts the value to float. |
02:57 | The dtype=type within bracket int() closing bracket argument in loadtxt converts the value to integer, as we require the data as integer further in the tutorial. |
03:11 | Now in-order to generate the scatter graph we will use the function scatter()closing brackets |
03:18 | Type scatter within closing bracket year comma profit and hit enter |
03:32 | Notice that we passed two arguments to scatter() function, first one the values in x-coordinate, year, and the other the values in y-coordinate, the profit percentage. |
03:57 | Plot a scatter plot of the same data in company-a-data.txt with red diamond markers. |
04:09 | Pause the video here, try out the following exercise and resume the video. |
04:17 | Now let us see another kind of plot, the pie chart, for the same data. |
04:40 | A pie chart or a circle graph is a circular chart divided into sectors, illustrating proportion. |
04:49 | Plot a pie chart representing the profit percentage of company A, with the same data from file company-a-data.txt. |
05:00 | So let us reuse the data we have loaded from the file previously. |
05:11 | We can plot the pie chart using the function pie()closing brackets |
05:15 | So Type pie within bracket profit comma labels=year |
05:29 | Notice that we passed two arguments to the function pie(). |
05:33 | First one the values and the next one the set of labels to be used in the pie chart. |
05:38 | Plot a pie chart with the same data with colors for each wedges as white, red, black, magenta,yellow, blue, green, cyan, yellow, magenta and blue respectively. |
05:58 | Pause the video here, try out the following exercise and resume the video. |
06:05 | Now let us move on to the bar charts. |
06:08 | A bar chart or bar graph is a chart with rectangular bars with lengths proportional to the values that they represent. |
06:19 | Plot a bar chart representing the profit percentage of company A, with the same data from file company-a-data.txt. |
06:30 | So let us reuse the data we have loaded from the file previously. |
06:34 | We can plot the bar chart using the function bar() and hit enter. |
06:44 | So inside that bracket you can put bar ( year , profit ) |
06:52 | Note that the function bar()needs at least two arguments one the values in x-coordinate and the other values in y-coordinate which is used to determine the height of the bars. |
07:05 | Plot a bar chart which is not filled and which is hatched with 45 degree slanting lines as shown in the image. |
07:17 | The data for the chart may be obtained from the file company-a-data.txt |
07:26 | Type bar within bracket year comma profit comma fill=False comma hatch= within single quote slashhit enter |
08:05 | Now let us move on to the log-log plot. |
08:10 | A log-log graph or a log-log plot is a two-dimensional graph of numerical data that uses logarithmic scales on both the horizontal and vertical axes. |
08:24 | Because of the nonlinear scaling of the axes, a function of the form y = ax^b will appear as a straight line on a log-log graph |
08:38 | Plot a log-log chart of y=5 into x3for x from 1-20. |
08:49 | Before we actually plot let us calculate the points needed for that. |
08:54 | x = linspace within brackets 1 comma 20 comma 100
y = 5 into x into 3 |
09:23 | Here is the syntax of the log-log function. |
09:28 | Now we can plot the log-log chart using loglog()function, |
09:34 | Type loglog within brackets x comma y hit enter |
09:48 | To understand the difference between a normal plot and a log-log plot let us create another plot using the function plot. |
09:57 | figure within brackets 2 THen type plot within brackets x comma y |
10:24 | The difference is clear.So that was log-log() plot. |
10:33 | Now we will see few more plots and also see how to access help of matplotlib over the Internet. |
10:43 | Help about matplotlib can be obtained from matplotlib.sourceforge.net/contents.html |
10:55 | More plots can be seen at matplotlib.sourceforge.net slash users slash screenshots.html and also at matplotlib.sourceforge.net slash gallery.html |
11:13 | This brings us to the end of this tutorial. In this tutorial we learnt to, |
11:20 | Plot a scatter plot using scatter() function |
11:22 | Plot a pie chart using pie() function |
11:25 | Plot a bar chart using bar() function |
11:28 | Plot a log-log graph using loglog() function |
11:33 | Access the matplotlib online help.Thank you. |
11:42 | So there are few some self assessment questions for you to solve. |
11:46 | scatter x comma y comma color=blue marker= d and plot x comma y comma color=b comma marker= d) does exactly the same. |
12:04 | Is True or False? |
12:07 | What statement can be issued to generate a bar chart with vertical line hatching. |
12:15 | bar within function x comma y comma color=in single quote w comma hatch= slash |
12:27 | bar within bracket x comma y comma fill=False comma hatch=slash slash |
12:38 | bar within bracket x comma y comma fill=False comma hatch=in single quote |
12:52 | bar within bracket x comma y comma color= within quote w comma hatch=single quote |
13:02 | And now the answers, |
13:06 | False. |
13:09 | Both functions do not produce the same kind of plot. |
13:13 | bar x comma y comma fill=False comma hatch=bar is the correct option to generate a bar chart with vertical line hatching. |
13:31 | Hope you have enjoyed this tutorial and found it useful. |
13:34 | Thank you! |