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How to get random rows with special condition in R
The 2019 Stack Overflow Developer Survey Results Are InHow to sort a dataframe by multiple column(s)Filter data.frame rows by a logical conditionGrouping functions (tapply, by, aggregate) and the *apply familyHow to make a great R reproducible exampleHow to unload a package without restarting RFind the day of a weekAggregate / summarize multiple variables per group (e.g. sum, mean)Return data subset time frames within another timeframes?Extracting a random sample of rows in a data.frame with a nested conditionaldata.table vs dplyr: can one do something well the other can't or does poorly?
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Hello how can I get 2 random rows with special condition. The example below are dates and I want to get a random sample of 2 dates with any year but month and day is 12/31. So it's like "XXXX1231".
> dateDS
dateDS
1 20121231
2 20131020
3 20140819
4 20151231
5 20161231
6 20171106
7 20131231
And I want to get a random sample that would output 2 dates ("XXXX1231")
> dateSample
dateSample
1 20121231
2 20131231
r
asked Mar 8 at 8:43
Mr. BusterMr. Buster
484
add a comment |
Hello how can I get 2 random rows with special condition. The example below are dates and I want to get a random sample of 2 dates with any year but month and day is 12/31. So it's like "XXXX1231".
> dateDS
dateDS
1 20121231
2 20131020
3 20140819
4 20151231
5 20161231
6 20171106
7 20131231
And I want to get a random sample that would output 2 dates ("XXXX1231")
> dateSample
dateSample
1 20121231
2 20131231
r
asked Mar 8 at 8:43
Mr. BusterMr. Buster
484
add a comment |
Hello how can I get 2 random rows with special condition. The example below are dates and I want to get a random sample of 2 dates with any year but month and day is 12/31. So it's like "XXXX1231".
> dateDS
dateDS
1 20121231
2 20131020
3 20140819
4 20151231
5 20161231
6 20171106
7 20131231
And I want to get a random sample that would output 2 dates ("XXXX1231")
> dateSample
dateSample
1 20121231
2 20131231
r
asked Mar 8 at 8:43
Mr. BusterMr. Buster
484
Hello how can I get 2 random rows with special condition. The example below are dates and I want to get a random sample of 2 dates with any year but month and day is 12/31. So it's like "XXXX1231".
> dateDS
dateDS
1 20121231
2 20131020
3 20140819
4 20151231
5 20161231
6 20171106
7 20131231
And I want to get a random sample that would output 2 dates ("XXXX1231")
> dateSample
dateSample
1 20121231
2 20131231
r
r
asked Mar 8 at 8:43
Mr. BusterMr. Buster
484
asked Mar 8 at 8:43
Mr. BusterMr. Buster
484
asked Mar 8 at 8:43
Mr. BusterMr. Buster
484
asked Mar 8 at 8:43
Mr. BusterMr. Buster
484
asked Mar 8 at 8:43
Mr. BusterMr. Buster
484
484
add a comment |
add a comment |
2 Answers
2
active
oldest
votes
One way using grep find indices of dates which ends with "1231" and then subset them.
df[sample(grep("1231$", df$dateDS), 2), ,drop = FALSE]
# dateDS
#5 20161231
#4 20151231
Or if you want just values of those dates and don't want to subset
sample(grep("1231$", df$dateDS, value = TRUE), 2)
#[1] "20151231" "20161231"
Another option, convert the dateDS to actual date extract month and date and randomly select two values with "1231" in it.
df$dateDS[sample(which(format(as.Date(as.character(df$dateDS), "%Y%m%d"), "%m%d") == "1231"), 2)]
answered Mar 8 at 8:47
Ronak ShahRonak Shah
45.8k104268
add a comment |
Another option with substr() in order to select only dates with 1231, then sample two rows:
d <- read.table(text="dateDS
20121231
20131020
20140819
20151231
20161231
20171106
20131231", header=T)
d$md <- substr(d$dateDS, 5, 8) # use md to select only "1231"
d <- d[d$md==1231, ]
# d ateDS md
# 1 20121231 1231
# 4 20151231 1231
# 5 20161231 1231
# 7 20131231 1231
d[sample(2), -2]
#[1] 20151231 20121231
answered Mar 8 at 8:50
RLaveRLave
5,29911227
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
One way using grep find indices of dates which ends with "1231" and then subset them.
df[sample(grep("1231$", df$dateDS), 2), ,drop = FALSE]
# dateDS
#5 20161231
#4 20151231
Or if you want just values of those dates and don't want to subset
sample(grep("1231$", df$dateDS, value = TRUE), 2)
#[1] "20151231" "20161231"
Another option, convert the dateDS to actual date extract month and date and randomly select two values with "1231" in it.
df$dateDS[sample(which(format(as.Date(as.character(df$dateDS), "%Y%m%d"), "%m%d") == "1231"), 2)]
answered Mar 8 at 8:47
Ronak ShahRonak Shah
45.8k104268
add a comment |
One way using grep find indices of dates which ends with "1231" and then subset them.
df[sample(grep("1231$", df$dateDS), 2), ,drop = FALSE]
# dateDS
#5 20161231
#4 20151231
Or if you want just values of those dates and don't want to subset
sample(grep("1231$", df$dateDS, value = TRUE), 2)
#[1] "20151231" "20161231"
Another option, convert the dateDS to actual date extract month and date and randomly select two values with "1231" in it.
df$dateDS[sample(which(format(as.Date(as.character(df$dateDS), "%Y%m%d"), "%m%d") == "1231"), 2)]
answered Mar 8 at 8:47
Ronak ShahRonak Shah
45.8k104268
add a comment |
One way using grep find indices of dates which ends with "1231" and then subset them.
df[sample(grep("1231$", df$dateDS), 2), ,drop = FALSE]
# dateDS
#5 20161231
#4 20151231
Or if you want just values of those dates and don't want to subset
sample(grep("1231$", df$dateDS, value = TRUE), 2)
#[1] "20151231" "20161231"
Another option, convert the dateDS to actual date extract month and date and randomly select two values with "1231" in it.
df$dateDS[sample(which(format(as.Date(as.character(df$dateDS), "%Y%m%d"), "%m%d") == "1231"), 2)]
answered Mar 8 at 8:47
Ronak ShahRonak Shah
45.8k104268
One way using grep find indices of dates which ends with "1231" and then subset them.
df[sample(grep("1231$", df$dateDS), 2), ,drop = FALSE]
# dateDS
#5 20161231
#4 20151231
Or if you want just values of those dates and don't want to subset
sample(grep("1231$", df$dateDS, value = TRUE), 2)
#[1] "20151231" "20161231"
Another option, convert the dateDS to actual date extract month and date and randomly select two values with "1231" in it.
df$dateDS[sample(which(format(as.Date(as.character(df$dateDS), "%Y%m%d"), "%m%d") == "1231"), 2)]
answered Mar 8 at 8:47
Ronak ShahRonak Shah
45.8k104268
answered Mar 8 at 8:47
Ronak ShahRonak Shah
45.8k104268
answered Mar 8 at 8:47
Ronak ShahRonak Shah
45.8k104268
answered Mar 8 at 8:47
Ronak ShahRonak Shah
45.8k104268
45.8k104268
add a comment |
add a comment |
Another option with substr() in order to select only dates with 1231, then sample two rows:
d <- read.table(text="dateDS
20121231
20131020
20140819
20151231
20161231
20171106
20131231", header=T)
d$md <- substr(d$dateDS, 5, 8) # use md to select only "1231"
d <- d[d$md==1231, ]
# d ateDS md
# 1 20121231 1231
# 4 20151231 1231
# 5 20161231 1231
# 7 20131231 1231
d[sample(2), -2]
#[1] 20151231 20121231
answered Mar 8 at 8:50
RLaveRLave
5,29911227
add a comment |
Another option with substr() in order to select only dates with 1231, then sample two rows:
d <- read.table(text="dateDS
20121231
20131020
20140819
20151231
20161231
20171106
20131231", header=T)
d$md <- substr(d$dateDS, 5, 8) # use md to select only "1231"
d <- d[d$md==1231, ]
# d ateDS md
# 1 20121231 1231
# 4 20151231 1231
# 5 20161231 1231
# 7 20131231 1231
d[sample(2), -2]
#[1] 20151231 20121231
answered Mar 8 at 8:50
RLaveRLave
5,29911227
add a comment |
Another option with substr() in order to select only dates with 1231, then sample two rows:
d <- read.table(text="dateDS
20121231
20131020
20140819
20151231
20161231
20171106
20131231", header=T)
d$md <- substr(d$dateDS, 5, 8) # use md to select only "1231"
d <- d[d$md==1231, ]
# d ateDS md
# 1 20121231 1231
# 4 20151231 1231
# 5 20161231 1231
# 7 20131231 1231
d[sample(2), -2]
#[1] 20151231 20121231
answered Mar 8 at 8:50
RLaveRLave
5,29911227
Another option with substr() in order to select only dates with 1231, then sample two rows:
d <- read.table(text="dateDS
20121231
20131020
20140819
20151231
20161231
20171106
20131231", header=T)
d$md <- substr(d$dateDS, 5, 8) # use md to select only "1231"
d <- d[d$md==1231, ]
# d ateDS md
# 1 20121231 1231
# 4 20151231 1231
# 5 20161231 1231
# 7 20131231 1231
d[sample(2), -2]
#[1] 20151231 20121231
answered Mar 8 at 8:50
RLaveRLave
5,29911227
answered Mar 8 at 8:50
RLaveRLave
5,29911227
answered Mar 8 at 8:50
RLaveRLave
5,29911227
answered Mar 8 at 8:50
RLaveRLave
5,29911227
5,29911227
add a comment |
add a comment |
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