Re: [igraph] Question on the formula of out/in degree distribution

[address@hidden]



Hi

 

Thanks for your kind reply

 

I have read the docs about the degree distribution of the networks generated by static.power.law.game().

It seems that the degree distribution of these networks should be

 ,  where lamda is the power,   is a normalization constant and

(but this formula can not show the probability of the degree being zero)

 

Moreover, I have generated two networks and computed their degree-distribution to test if this formula were right.

 

The code is:

g1 <- static.power.law.game (1000000, 1000000, exponent.out = 2.2, exponent.in = 2.2)

g2 <- static.power.law.game (1000000, 1000000, exponent.out = 3.25, exponent.in = 3.25)

 

deg1<-degree(g1, mode="all")

indeg1<-degree(g1, mode="in")

outdeg1<-degree(g1, mode="out")

 

deg2<-degree(g2, mode="all")

indeg2<-degree(g2, mode="in")

outdeg2<-degree(g2, mode="out")

 

Then, I used matlab to plot the distribution of the degrees. (I am sorry that I do not know how to use R to plot different vectors in a same figure)

In the following figures, the symbols of stars, circles and plus are respectively represent 'deg1' (or 'deg2'), 'outdeg1' (or 'outdeg2'),  and 'indeg1' (or 'indeg2'),

and the solid line is the analytic result of the in-degree (or out-degree) distribution .

But the analytic line and the real data of in-degree (or out-degree) distribution are not fitted with each other.

 

 

Could anyone tell me where I am making the mistake?

 

best

Xueming

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address@hidden

 

From: Gábor Csárdi

Date: 2014-03-15 23:53

To: Help for igraph users

Subject: Re: [igraph] Question on the formula of out/in degree distribution

Hi, see the docs: http://igraph.org/r/doc/static.power.law.game.html

G.

On Sat, Mar 15, 2014 at 10:53 AM, address@hidden <address@hidden> wrote:

Hi

 

I want to use static.power.law.game() to generate directed scale-free network,

for example

g <- static.power.law.game(10000, 10000, 2.2, 2.2)

 

What is the formula of the out/in degree distribution?

 

best

Xueming

 

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address@hidden

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