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1 .. 2.5 LO: saving plots (2) |
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2 .. ------------------------- |
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3 .. * Outline |
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4 .. + basic savefig |
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5 .. + png, pdf, ps, eps, svg |
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6 .. + going to OS and looking at the file |
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7 |
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8 ======= |
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9 Savefig |
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10 ======= |
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11 |
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12 Hello and welcome to the tutorial. In this tutorial you will learn how |
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13 to save plots using Python. |
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14 |
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15 Start your IPython interpreter with the command :: |
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16 |
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17 ipython -pylab |
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18 |
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19 It will start your IPython interpreter with the required python |
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20 modules for plotting and saving your plots. |
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21 |
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22 {{{ Open ipython }}} |
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23 |
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24 Now let us plot something, let us plot a sine wave from minus 3 pi to |
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25 3 pi. Let us start by calculating the required points for the plot. It |
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26 can be done using linspace as, :: |
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27 |
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28 x = linspace(-3*pi,3*pi,100) |
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29 |
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30 We have stored required points in x. Now let us plot the points using |
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31 the statement :: |
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32 |
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33 plot(x,sin(x)) |
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34 |
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35 {{{ Keep the plot open }}} |
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36 |
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37 Done! we have made a very basic sine plot, now let us see how to save |
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38 the plot for future use so that you can embed the plot in your |
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39 reports. |
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40 |
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41 {{{ Switch the focus to IPython interpreter window }}} |
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42 |
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43 For saving the plot, we will use savefig function, and it has to be |
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44 done with the plot window open. The statement is, :: |
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45 |
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46 savefig('/home/fossee/sine.png') |
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47 |
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48 Notice that ``savefig`` function takes one argument which is a string |
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49 which is the filename. The last 3 characters after the ``.`` in the |
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50 filename is the extension or type of the file which determines the |
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51 format in which you want to save. |
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52 |
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53 {{{ Highlight the /home/fossee part using mouse movements }}} |
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54 |
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55 Also, note that we gave the full path or the absolute path to which we |
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56 want to save the file. |
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57 |
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58 {{{ Highlight the .png part using mouse movements }}} |
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59 |
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60 Here I have used an extension ``.png`` which means i want to save the |
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61 image as a PNG file. |
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62 |
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63 Now let us locate ``sine.png`` file saved. We saved the file to |
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64 ``/home/fossee`` so let us navigate to ``/home/fossee`` using the |
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65 file browser. |
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66 |
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67 {{{ Open the browser, navigate to /home/fossee and highlight the file |
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68 sine.png }}} |
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69 |
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70 Yes, the file ``sine.png`` is here and let us check it. |
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71 |
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72 {{{ Open the file sine.png and show it for two-three seconds and then |
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73 close it and return to IPython interpreter, make sure the plot window |
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74 is still open, also don't close the file browser window }}} |
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75 |
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76 So in-order to save a plot, we use ``savefig`` function. ``savefig`` |
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77 can save the plot in many formats, such as pdf - portable document |
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78 format, ps - post script, eps - encapsulated post script, svg - |
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79 scalable vector graphics, png - portable network graphics which |
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80 support transparency etc. |
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81 |
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82 .. #[[slide must give the extensions for the files - Anoop]] |
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83 |
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84 Let us now try to save the plot in eps format. ``eps`` stands for |
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85 encapsulated post script, and it can be embedded in your latex |
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86 documents. |
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87 |
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88 {{{ Switch focus to the already open plot window }}} |
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89 |
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90 We still have the sine plot with us, and now let us save the plot as |
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91 ``sine.eps``. |
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92 |
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93 {{{ Switch focus to IPython interpreter }}} |
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94 |
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95 Now, We will save the plot using the function ``savefig`` :: |
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96 |
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97 savefig('/home/fossee/sine.eps') |
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98 |
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99 {{{ Switch focus to file browser window }}} |
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100 |
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101 Now let us go to ``/home/fossee`` and see the new file created. |
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102 |
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103 {{{ Highlight the file sine.eps with a single mouse click for 2 |
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104 seconds and then double click and open the file }}} |
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105 |
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106 Yes! the new file ``sine.eps`` is here. |
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107 |
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108 Now you may try saving the same in pdf, ps, svg formats. |
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109 |
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110 Let us review what we have learned in this session! We have learned to |
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111 save plots in different formats using the function ``savefig()``. |
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112 |
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113 Thank you! |
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114 |
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115 .. Author: Anoop Jacob Thomas <anoop@fossee.in> |
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116 Reviewer 1: |
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117 Reviewer 2: |
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118 External reviewer: |