[Tutor] How to plot amount of lines but the amount is a input

[Joel Goldstick]

On Wed, Dec 30, 2015 at 6:35 AM, Alan Gauld <alan.gauld at btinternet.com>
wrote:

> On 30/12/15 05:55, Tom Xu wrote:
> > Dear Pythoneers,
> >
> > I want to draw several curves in one graph, but the amount of curves is
> not
> > a fixed number.
>
> OK, But what exactly are you asking us to do?
>
> > My homework is below:
> > ---
> > import matplotlib.pyplot as plt
> > import math
> >
> > if __name__=='__main__':
> >     try:
> >         n=int(input('how many curves? '))
> >         ulist=[]
> >         thetalist=[]
> >         for i in range(n):
> >             ulist.append(float(input('Enter velocity: ')))
> >             thetalist.append(float(input('Enter angle: ')))
> >     except ValueError:
> >         print('invalid input')
> >     else:
> >         generateFr(?????)
>
> You need to put the call to generateFr inside a loop that
> iterates n times putting successive values from ulist and
> thetalist into the function.
>
> Also, put the function definitions above the place where you call them.
Normally, the if __name__ stuff should be below your function definitions

>
> > def generateFr(u, theta):
> >     theta=math.radians(theta)
> >     g=9.8
> >
> >     tflight=2*u*math.sin(theta)/g
> >     intervals=frange(0, tflight, 0.001)
> >     x=[]
> >     y=[]
> >     for t in intervals:
> >         x.append(u*math.cos(theta)*t)
> >         y.append(u*math.sin(theta)*t - 0.5*g*t*t)
> >     drawgraph(x, y)
> >
> > def frange(start, final, increment):
> >     numbers=[]
> >     while start<final:
> >         numbers.append(start)
> >         start+=increment
> >     return numbers
> >
> > def drawgraph(x, y):
> >     plt.plot(x, y)
> >     plt.xlabel('x-coordinate')
> >     plt.ylabel('y-coordinate')
> >     plt.title('Projectile motion')
>
>
>
> --
> Alan G
> Author of the Learn to Program web site
> http://www.alan-g.me.uk/
> http://www.amazon.com/author/alan_gauld
> Follow my photo-blog on Flickr at:
> http://www.flickr.com/photos/alangauldphotos
>
>
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-- 
Joel Goldstick
http://joelgoldstick.com/stats/birthdays