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1 Hello and welcome to the tutorial on creating simple plots using |
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2 Python.This tutorial is presented by the Fossee group. |
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3 {{{ Show the Title Slide }}} |
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4 |
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5 I hope you have IPython running on your computer. |
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6 |
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7 In this tutorial we will look at plot command and also how to study |
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8 the plot using the UI. |
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9 |
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10 {{{ Show Outline Slide }}} |
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11 |
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12 Lets start ipython on your shell, type :: |
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13 |
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14 $ipython -pylab |
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15 |
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16 |
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17 Pylab is a python library which provides plotting functionality.It |
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18 also provides many other important mathematical and scientific |
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19 functions. After running IPython -pylab in your shell if at the top of |
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20 the result of this command, you see something like :: |
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21 |
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22 |
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23 `ERROR: matplotlib could NOT be imported! Starting normal |
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24 IPython.` |
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25 |
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26 |
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27 {{{ Slide with Error written on it }}} |
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28 |
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29 Then you have to install matplotlib and run this command again. |
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30 |
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31 Now type in your ipython shell :: |
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32 |
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33 In[]: linpace? |
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34 |
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35 |
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36 |
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37 as the documentation says, it returns `num` evenly spaced samples, |
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38 calculated over the interval start and stop. To illustrate this, lets |
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39 do it form 1 to 100 and try 100 points. :: |
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40 |
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41 In[]: linspace(1,100,100) |
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42 |
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43 As you can see a sequence of numbers from 1 to 100 appears. |
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44 |
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45 Now lets try 200 points between 0 and 1 you do this by typing :: |
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46 |
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47 |
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48 In[]: linspace(0,1,200) |
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49 |
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50 0 for start , 1 for stop and 200 for no of points. In linspace |
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51 the start and stop points can be integers, decimals , or |
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52 constants. Let's try and get 100 points between -pi to pi. Type :: |
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53 |
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54 In[]: p = linspace(-pi,pi,100) |
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55 |
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56 |
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57 'pi' here is constant defined by pylab. Save this to the variable, p |
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58 . |
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59 |
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60 If you now :: |
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61 |
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62 In[]: len(p) |
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63 |
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64 You will get the no. of points. len function gives the no of elements |
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65 of a sequence. |
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66 |
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67 |
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68 Let's try and plot a cosine curve between -pi and pi using these |
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69 points. Simply type :: |
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70 |
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71 |
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72 In[]: plot(p,cos(points)) |
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73 |
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74 Here cos(points) gets the cosine value at every corresponding point to |
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75 p. |
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76 |
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77 |
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78 We can also save cos(points) to variable cosine and plot it using |
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79 plot.:: |
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80 |
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81 In[]: cosine=cos(points) |
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82 |
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83 In[]: plot(p,cosine) |
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84 |
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85 |
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86 |
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87 Now do :: |
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88 |
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89 In[]: clf() |
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90 |
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91 this will clear the plot. |
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92 |
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93 This is done because any other plot we try to make shall come on the |
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94 same drawing area. As we do not wish to clutter the area with |
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95 overlaid plots , we just clear it with clf(). Now lets try a sine |
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96 plot. :: |
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97 |
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98 |
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99 In []: plot(p,sin(p)) |
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100 |
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101 |
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102 |
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103 |
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104 The Window on which the plot appears can be used to study it better. |
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105 |
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106 First of all moving the mouse around gives us the point where mouse |
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107 points at. |
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108 |
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109 Also we have some buttons the right most among them is |
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110 for saving the file. |
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111 |
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112 Just click on it specifying the name of the file. We will save the plot |
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113 by the name sin_curve in pdf format. |
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114 |
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115 {{{ Action corelating with the words }}} |
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116 |
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117 As you can see I can specify format of file. |
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118 Left to the save button is the slider button to specify the margins. |
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119 |
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120 {{{ Action corelating with the words }}} |
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121 |
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122 Left to this is zoom button to zoom into the plot. Just specify the |
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123 region to zoom into. |
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124 The button left to it can be used to move the axes of the plot. |
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125 |
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126 {{{ Action corelating with the words }}} |
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127 |
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128 The next two buttons with a left and right arrow icons change the state of the |
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129 plot and take it to the previous state it was in. It more or less acts like a |
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130 back and forward button in the browser. |
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131 |
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132 {{{ Action corelating with the words }}} |
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133 |
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134 The last one is 'home' referring to the initial plot. |
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135 |
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136 {{{ Action corelating with the words}}} |
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137 |
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138 |
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139 |
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140 {{{ Summary Slide }}} |
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141 |
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142 |
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143 In this tutorial we have looked at |
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144 |
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145 1. Starting Ipython with pylab |
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146 |
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147 2. Using linspace function to create `num` equaly spaced points in a region. |
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148 |
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149 3. Finding length of sequnces using len. |
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150 |
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151 4. Plotting mathematical functions using plot. |
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152 |
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153 4. Clearing drawing area using clf |
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154 |
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155 5. Using the UI of plot for studying it better . Using functionalities like save , zoom , moving the plots on x and y axis |
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156 |
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157 etc .. |
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158 |
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159 |
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160 |
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161 {{{ Show the "sponsored by FOSSEE" slide }}} |
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162 |
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163 |
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164 |
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165 This tutorial was created as a part of FOSSEE project, NME ICT, MHRD India |
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167 |
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168 |
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169 Hope you have enjoyed and found it useful. |
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170 |
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171 Thankyou |
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172 |
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173 |
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174 |
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175 Author : Amit Sethi |
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176 Internal Reviewer : |
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177 Internal Reviewer 2 : |