PRIP 8.1 Sumita Arora Solutions | Class 12 Computer Science

(i)First, import pyplot ( write command for it below)
Answer:   import matplotlib.pyplot as plt

(ii) Now generate a list ML having 10 elements, but in which each element is the square of its position in the list: Complete the code below:
import _______
ML = [ ] 
for _ in ____:
    ML.append(i*i)
Answer:

Code: 
import matplotlib.pyplot as plt
        ML = [] 
        for i in range(10):
ML.append(i*i)

(iii) Now simply plot the sequence ML with a plot(). That is, run the following code now.
plt.plot(ML) 
plt.show() 
See what happens? Paste the result below:
Answer: 


(iv) Save it as the file first.png. Write command below.
Answer:  plt.savefig('first.png')

(i) Sequence L2 contains cos values for each of the value of L1. Write code below to create L2:
Answer:   l2 = np.cos(l1) 

(ii) Now write command to plot a graph x- versus y- :
Answer:plt.plot(l1, l2) 
        plt.show()

(iii) What is the result produced by above code? Paste the result below:
Answer: 


(iv) Save the result in file second.pdf in folder c:\data. Carefully give the path by doubling the slashes. Write command below.
Answer:  plt.savefig('C:\data\second.pdf')
 
(v) Now modify the above code and add a proper title using title() for the chart and for the X-axis and Y-axis using functions xlabel() and ylabel(). (Write code for this below)
Answer: 

plt.title('Title for graph') # function to give title to graph
plt.xlabel('values')       # function to add x label
plt.ylabel('cos values')   # function to add y label

(i) Run the above code and paste its result below:
Answer:

(ii) Add a third line chart to above plot with log values for each value of sequence x i.e., x vs log(x).
Add code for the same in above code:
Answer:

Code:
import matplotlib.pyplot as plt 
import numpy as np
x = np.linspace(0, 10, 100) 
plt.plot(x, np.sin(x)) 
plt.plot(x, np.cos(x)) 
plt.plot(x[1:], np.log(x[1:]))
# plt.plot(x, np.log(x))# this gives error RuntimeWarning: divide by zero encountered in log

(iii) Run the code and paste its result below:
Answer: plt.show()

(iv)Change line style for sin curve as ‘–’ of olive color, for cos curve as ’-’ blue color and continuous line for log curve of silver color. (write code below)
Answer:

Code:
import matplotlib.pyplot as plt 
import numpy as np
x = np.linspace(0, 10, 100) 
plt.plot(x, np.sin(x), '-', color="olive") 
plt.plot(x, np.cos(x), '--', color="blue") 
plt.plot(x[1:], np.log(x[1:]), color="silver")
# plt.plot(x, np.log(x))# this gives error RuntimeWarning: divide by zero encountered in log

(v) Add legends to above plot, labeling as “Sin curve”, “Cos curve” and “Log curve”. The position of legends should be lower right.
Answer:

Code:
import matplotlib.pyplot as plt 
import numpy as np
x = np.linspace(0, 10, 100) 
sin, = plt.plot(x, np.sin(x), '-', color="olive",label = "sin curve" ) 
cos, = plt.plot(x, np.cos(x), '--', color="blue", label = "soc curve") 
log, = plt.plot(x[1:], np.log(x[1:]), color="silver",label = "log curve")

# plt.plot(x, np.log(x)) # this gives error RuntimeWarning: divide by zero encountered in log

plt.legend(handles=[sin, cos, log], loc= "lower right")

(vi) Paste the result of above command below:
Answer:


(vii) Save the above figure
Answer: plt.savefig('sin_cos_log.png')

(i) Write code to create sequence preci given above.
Answer:
perci =np.array([17.78, 19.05, 46.99, 74.422, 77.47, 51.308, 49.022, 41.148, 46.736, 33.274, 35.306, 21.336 ])

(ii) Write code to create a sequence Months storing names of twelve months.
Answer:
months = np.array(["January", "February", "March", "April", "May", "June", "July", "August", "September","October", "November", "December"])

(iii) Write code to create a bar chart plotting the precipitation values for tweleve months i.e., sequence preci. Months (write code below)
Answer:  plt.bar(months,perci)

(iv) Paste the result of above code below:
Answer: plt.show()


(v) Change the above code so that the color of the bar is black and width of bar becomes 0.3.
Answer: plt.bar(months,perci, color = 'b', width = 0.3)

(vi) Also, add titles for the chart, for x-axis and y-axis.
Answer:

plt.bar(months,perci, color = 'b', width = 0.3)
plt.xlabel('Months')
plt.ylabel('precipitation')
plt.title('precipitation in a year')

(vii) Change the ticks on the X-axis so that it now displays month number in place of the month name. (Use xticks())
Answer:

index = np.arange(1,len(months)+1)
plt.bar(index,perci, color = 'b', width = 0.3)
plt.xlabel('Months')
plt.ylabel('precipitation')
plt.xticks(index)
plt.title('precipitation in a year')
plt.show()

(viii) Paste the result below:
Answer:


(ix) Create horizontal bar chart using the same data as above (write the code below)
Answer:

index = np.arange(1,len(months)+1)
plt.barh(index,perci,0.3,color='b')
plt.xlabel('Months')
plt.ylabel('precipitation')
plt.yticks(index)
plt.title('precipitation in a year')
plt.show()

(x) Paste the result below:
Answer:

(i) Use the sequences precipitation and months data from the previous question and plot a pie chart. The Month names should appear on the pie chart ( write code below).
Answer: plt.pie(perci, labels=months)
        plt.show()

(ii) Show the June and November months exploded on the pie chart.
Answer:

exploded = (0, 0, 0, 0, 0, 0.1, 0, 0, 0, 0, 0.1, 0)
plt.pie(perci, explode=exploded, labels=months)
plt.show()

(iii) Show the percentages values on the pie chart with 3 decimal points and a percentage sign.
Answer:

exploded = (0, 0, 0, 0, 0, 0.1, 0, 0, 0, 0, 0.1, 0)
plt.pie(perci, explode=exploded, autopct='%1.3f%%', labels=months)
plt.show()

(iv) Paste the result below:
Answer:

(i) Create sequences HighTmp, LowTmp, RainFall, RelHumid from the above data Write code below:
Answer:

HighTmp = np.array([31.1, 31.3, 32.8, 33.2, 33.6, 32.4, 30.4, 30.0, 30.7, 33.4, 33.7, 32.4]) 
LowTmp = np.array([17.3, 18.2, 21.4, 24.2, 27.0, 26.6, 25.5, 25.1, 24.8, 23.8, 21.3, 18.5]) 
RainFall = np.array([0.3, 0.4, 0.0, 0.1, 11.3, 493.1, 840.7, 585.2, 341.4, 89.3, 9.9, 1.6])
RelHumid = np.array([69, 67, 69, 71, 70, 80, 86, 86, 83, 78, 71, 69])
months = np.array(["January", "February", "March", "April", "May", "June", "July", "August", "September","October", "November", "December"])

(ii) Plot these four sequences on a bar chart where red color shows the HighTmp sequence, blue color shows the LowTmp sequence, olive color depicts the RainFall sequence and silver color depicts the RelHumid sequence.
Answer:

width = 0.2
plt.figure(figsize=(10,10))   # to increase size of bar chart
plt.bar(index-0.4,HighTmp, width, color = 'red')
plt.bar(index-0.2,LowTmp, width, color = 'blue')
plt.bar(index,RainFall, width, color = 'olive')
plt.bar(index+0.2,RelHumid, width, color = 'silver')
plt.xticks(index, months) # set labels manually
plt.show()

(iii) Paste the result below:
Answer:


(iv) Make widths of these bars as 0.28.
Answer:

width = 0.28
plt.figure(figsize=(10,10))   # to increase size of bar chart
plt.bar(index-0.56,HighTmp, width, color = 'red')
plt.bar(index-0.28,LowTmp, width, color = 'blue')
plt.bar(index,RainFall, width, color = 'olive')
plt.bar(index+0.28,RelHumid, width, color = 'silver')
plt.xticks(index, months) # set labels manually
plt.show()

(v) Change the Xticks such that they display the month names ( numbers ) in place of month names
Answer:

width = 0.28
plt.figure(figsize=(10,10))   # to increase size of bar chart
plt.bar(index-0.56,HighTmp, width, color = 'red')
plt.bar(index-0.28,LowTmp, width, color = 'blue')
plt.bar(index,RainFall, width, color = 'olive')
plt.bar(index+0.28,RelHumid, width, color = 'silver')
plt.xticks(index) 
plt.show()

(vi) Paste the result below:
Answer:


(vii) Add legends for these providing meaningful labels for these sequences.
Answer:


width = 0.28
plt.figure(figsize=(10,10))   # to increase size of bar chart
plt.bar(index-0.56,HighTmp, width, color = 'red')
plt.bar(index-0.28,LowTmp, width, color = 'blue')
plt.bar(index,RainFall, width, color = 'olive')
plt.bar(index+0.28,RelHumid, width, color = 'silver')
plt.xticks(index) 
handles = ["High Tmp","Low Tmp","Rainfall","Rel Humid"]   # legends added
plt.legend(handles)

plt.show() 

(viii) Give appropriate title for the chart and the axes.
Answer:

width = 0.28
plt.figure(figsize=(10,10))   # increase size of graph
plt.bar(index-0.56,HighTmp, width, color = 'red')
plt.bar(index-0.28,LowTmp, width, color = 'blue')
plt.bar(index,RainFall, width, color = 'olive')
plt.bar(index+0.28,RelHumid, width, color = 'silver')
plt.xticks(index) 

plt.xlabel('Months')                          # xlabel ylabel title
plt.ylabel('temp/humidity/rainfall')
plt.title('Rainfall in a year')

handles = ["High Tmp","Low Tmp","Rainfall","Rel Humid"]   # legends added
plt.legend(handles)
plt.show() 

(ix) Paste the result below:
Answer:


(x) Save the chart as “multibar.pdf”.
Answer:
# image should be saved before plt.show()
plt.savefig('multibar.pdf')   # saving figure