I'm just learning Python and I'm wondering if someone could help me get the chart to render properly in the following code, i.e. plot the sequence of data points. I have put print statements so I can see if the calculations are correct which they are.

Thanks

from pylab import *

def some_function(ff, dd):
    if dd >=0 and dd <=200:
        tt = (22/-90)*ff+24
    elif dd >=200 and dd <=1000:
        st = (22/-90)*(ff)+24
        gg = (st-2)/-800
        tt = gg*dd+(gg*-1000+2)
    else:
        tt = 2.0
    return tt

ff = float(25)
for dd in range (0, 1200, 100):
    tt1 = some_function(ff, dd)
    plot(dd,tt1)
    print(dd)
    print(tt1)
title("Something")
xlabel("x label")
ylabel("y label")
show()

2 Answers

1
Bazingaa On Best Solutions

Since you are plotting one point at a time, you need either a scatter plot or a plot with markers

for dd in range (0, 1200, 100):
    tt1 = some_function(ff, dd)
    scatter(dd, tt1) # Way number 1
    # plot(dd,tt1, 'o') # Way number 2

enter image description here

EDIT (answering your second question in the comments below): Save the results in a list and plot outside the for loop

result = []
dd_range = range (0, 1200, 100)
for dd in dd_range:
    tt1 = some_function(ff, dd)
    result.append(tt1)
plt.plot(dd_range, result, '-o')   

enter image description here

1
foglerit On

You can vectorize your function and work with NumPy arrays to avoid the for-loop and better inform matplotlib of what you want to plot

import numpy as np
from pylab import *

def some_function(ff, dd):
    if dd >=0 and dd <=200:
        tt = (22/-90)*ff+24
    elif dd >=200 and dd <=1000:
        st = (22/-90)*(ff)+24
        gg = (st-2)/-800
        tt = gg*dd+(gg*-1000+2)
    else:
        tt = 2.0
    return tt

vectorized_some_function = np.vectorize(some_function)

ff = float(25)
dd = np.linspace(0, 1100, 12)
tt = vectorized_some_function(ff, dd)
plot(dd, tt)
title("Something")
xlabel("x label")
ylabel("y label")
show()

plot