Imposing more than one condition to if

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No idea of how to do what you want but your data set is not working.
I think that you want

 x= c(1:24)
day= rep(1:30, each=10)
time= sample(x, 300, replace= T)
light= rep(c(20,10,6,0,0,0,0,0,8,20), 30)
d=data.frame(day,time,light)
n= length(day)

John Kane
Kingston ON Canada
-----Original Message-----
From: sguallar at yahoo.com
Sent: Sun, 15 Jul 2012 09:32:33 -0700 (PDT)
To: r-help at r-project.org
Subject: [R] Imposing more than one condition to if

Hi,

I have a dataset which contains several time records for a number of
days, plus a variable (light) that allows to determine night time (lihgt=
0) and daytime (light> 0). I need to obtain get dusk time and dawn time
for each day and place them in two columns.

This is the starting point (d):
day time light
1     1       20
1     12     10
1     11     6
1     9       0
1     6       0
1     12     0
...
30     8     0
30     3     0
30     8     0
30     3     0
30     8     8
30     9     20

And this what I want to get:
day time light dusk dawn
1     1      20     11     10
1     12    10     11     10
1     11     6      11     10
1     9       0      11     10
1     6       0      11     10
1     12     0      11     10
...
30     8     0       9     5
30     3     0       9     5
30     8     0       9     5
30     3     0       9     5
30     8     8       9     5
30     9     20     9     5

This is the code for data frame d:
day= rep(1:30, each=10)
n= length(dia); x= c(1:24)
time= sample(x, 300, replace= T)
light= rep(c(20,10,6,0,0,0,0,0,8,20), 30)
d=data.frame(day,time,light)

I'd need to impose a double condition like the next but if does not take
more than one:
attach(d)
for (i in 1: n){
if (light[i-1]>2 & light[i]<2){
d$dusk<- time[i-1]
}
if (light[i-1]<2 & light[i]>2){
d$dawn<- time[i]
}
}
detach(d)
d

Thank you for your help
	[[alternative HTML version deleted]]

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Hello,

There are obvious bugs in your code, you are testing for light > 2 or 
ligth < 2 but this would mean that dusk and dawn are undetermined for 
light == 2 and that they happen at light == 1.

Without loops or compound logical conditions:

f <- function(x){
	x$dawn <- x$time[ which.min(x$light) ]
	x$dusk <- x$time[ max(which(x$light == 0)) + 1 ]
	x
}

do.call(rbind, by(d, d$day, f))

Hope this helps,

Rui Barradas

Em 15-07-2012 17:32, Santiago Guallar escreveu:
Hi,

I have a dataset which contains several time records for a number of days, plus a variable (light) that allows to determine night time (lihgt= 0) and daytime (light> 0). I need to obtain get dusk time and dawn time for each day and place them in two columns.

This is the starting point (d):
day time light
1     1       20
1     12     10
1     11     6
1     9       0
1     6       0
1     12     0
...
30     8     0
30     3     0
30     8     0
30     3     0
30     8     8
30     9     20

And this what I want to get:
day time light dusk dawn
1     1      20     11     10
1     12    10     11     10
1     11     6      11     10
1     9       0      11     10
1     6       0      11     10
1     12     0      11     10
...
30     8     0       9     5
30     3     0       9     5
30     8     0       9     5
30     3     0       9     5
30     8     8       9     5
30     9     20     9     5

This is the code for data frame d:
day= rep(1:30, each=10)
n= length(dia); x= c(1:24)
time= sample(x, 300, replace= T)
light= rep(c(20,10,6,0,0,0,0,0,8,20), 30)
d=data.frame(day,time,light)

I'd need to impose a double condition like the next but if does not take more than one:
attach(d)
for (i in 1: n){
if (light[i-1]>2 & light[i]<2){
d$dusk<- time[i-1]
}
if (light[i-1]<2 & light[i]>2){
d$dawn<- time[i]
}
}
detach(d)
d

Thank you for your help
	[[alternative HTML version deleted]]

______________________________________________
R-help at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

try this:
set.seed(1)
day= rep(1:30, each=10)
n= length(day); x= c(1:24)
time= sample(x, 300, replace= T)
light= rep(c(20,10,6,0,0,0,0,0,8,20), 30)
d=data.frame(day,time,light)

# create a dawn/dusk column to mark where it happens
d$dawn <- c(FALSE, (head(d$light, -1) < 2) & (tail(d$light, -1) > 2))
d$dusk <- c((head(d$light, -1) > 2) & (tail(d$light, -1) < 2), FALSE)

# now split and recombine to get the values for the day
result <- do.call(rbind, lapply(split(d, d$day), function(.day){
+     # create new dataframe with the values
+     cbind(.day[, c('day', 'time', 'light')]
+         , dawn = .day$time[.day$dawn]
+         , dusk = .day$time[.day$dusk]
+         )
+ }))

result
day time light dawn dusk
1.1      1    7    20   16   14
1.2      1    9    10   16   14
1.3      1   14     6   16   14
1.4      1   22     0   16   14
1.5      1    5     0   16   14
1.6      1   22     0   16   14
1.7      1   23     0   16   14
1.8      1   16     0   16   14
1.9      1   16     8   16   14
1.10     1    2    20   16   14
2.11     2    5    20   10   17
2.12     2    5    10   10   17
2.13     2   17     6   10   17
2.14     2   10     0   10   17
2.15     2   19     0   10   17
2.16     2   12     0   10   17
2.17     2   18     0   10   17
2.18     2   24     0   10   17
2.19     2   10     8   10   17
2.20     2   19    20   10   17
3.21     3   23    20   21   16
3.22     3    6    10   21   16
3.23     3   16     6   21   16
3.24     3    4     0   21   16
3.25     3    7     0   21   16
3.26     3   10     0   21   16
3.27     3    1     0   21   16
3.28     3   10     0   21   16
3.29     3   21     8   21   16
3.30     3    9    20   21   16
4.31     4   12    20   18   12
4.32     4   15    10   18   12
4.33     4   12     6   18   12
4.34     4    5     0   18   12
4.35     4   20     0   18   12
4.36     4   17     0   18   12
4.37     4   20     0   18   12
4.38     4    3     0   18   12
4.39     4   18     8   18   12
4.40     4   10    20   18   12
Hi,

I have a dataset which contains several time records for a number of days, plus a variable (light) that allows to determine night time (lihgt= 0) and daytime (light> 0). I need to obtain get dusk time and dawn time for each day and place them in two columns.

This is the starting point (d):
day time light
1     1       20
1     12     10
1     11     6
1     9       0
1     6       0
1     12     0
...
30     8     0
30     3     0
30     8     0
30     3     0
30     8     8
30     9     20

And this what I want to get:
day time light dusk dawn
1     1      20     11     10
1     12    10     11     10
1     11     6      11     10
1     9       0      11     10
1     6       0      11     10
1     12     0      11     10
...
30     8     0       9     5
30     3     0       9     5
30     8     0       9     5
30     3     0       9     5
30     8     8       9     5
30     9     20     9     5

This is the code for data frame d:
day= rep(1:30, each=10)
n= length(dia); x= c(1:24)
time= sample(x, 300, replace= T)
light= rep(c(20,10,6,0,0,0,0,0,8,20), 30)
d=data.frame(day,time,light)

I'd need to impose a double condition like the next but if does not take more than one:
attach(d)
for (i in 1: n){
if (light[i-1]>2 & light[i]<2){
d$dusk<- time[i-1]
}
if (light[i-1]<2 & light[i]>2){
d$dawn<- time[i]
}
}
detach(d)
d

Thank you for your help
        [[alternative HTML version deleted]]

______________________________________________
R-help at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.