jcid<-subset(jcweall,V2==0)
jcid11<-subset(jcid,V10==11)
jcid13<-subset(jcid,V10==13)
jcfz11<-group_by(jcid11,V1)
jcfz13<-group_by(jcid13,V1)
new11<-summarise(jcfz11, last(V3*60+V4))
new13<-summarise(jcfz13, first(V3*60+V4))
newwe<-merge(new11,new13,by='V1')
i<-newwe$`first(V3 * 60 + V4)`
j<-newwe$`last(V3 * 60 + V4)`
k<-i-j
k<-k[k>=0&k<=100]
mean(k)

jcid<-subset(jcweall,V2==1)
jcid11<-subset(jcid,V10==11)
jcid13<-subset(jcid,V10==13)
jcfz11<-group_by(jcid11,V1)
jcfz13<-group_by(jcid13,V1)
new11<-summarise(jcfz11, last(V3*60+V4))
new13<-summarise(jcfz13, first(V3*60+V4))
newwe<-merge(new11,new13,by='V1')
i<-newwe$`first(V3 * 60 + V4)`
j<-newwe$`last(V3 * 60 + V4)`
k<-i-j
k<-k[k>=0&k<=100]
mean(k)

jcid<-subset(jcweall,V2==2)
jcid11<-subset(jcid,V10==11)
jcid13<-subset(jcid,V10==13)
jcfz11<-group_by(jcid11,V1)
jcfz13<-group_by(jcid13,V1)
new11<-summarise(jcfz11, last(V3*60+V4))
new13<-summarise(jcfz13, first(V3*60+V4))
newwe<-merge(new11,new13,by='V1')
i<-newwe$`first(V3 * 60 + V4)`
j<-newwe$`last(V3 * 60 + V4)`
k<-i-j
k<-k[k>=0&k<=100]
mean(k)

jcid<-subset(jcweall,V2==3)
jcid11<-subset(jcid,V10==11)
jcid13<-subset(jcid,V10==13)
jcfz11<-group_by(jcid11,V1)
jcfz13<-group_by(jcid13,V1)
new11<-summarise(jcfz11, last(V3*60+V4))
new13<-summarise(jcfz13, first(V3*60+V4))
newwe<-merge(new11,new13,by='V1')
i<-newwe$`first(V3 * 60 + V4)`
j<-newwe$`last(V3 * 60 + V4)`
k<-i-j
k<-k[k>=0&k<=100]
mean(k)

V2做循环求出mean的值，V2的范围是0到23