R: expand data frame columnwise with shifted rows of data - r

Question

- Example Data to work with:
To create a reduced example, this is the output of dput(df):
df <- structure(list(SubjectID = structure(c(1L, 1L, 1L, 1L, 1L, 1L,
1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 3L, 3L,
3L, 3L), .Label = c("1", "2", "3"), class = "factor"), EventNumber = structure(c(1L,
1L, 1L, 1L, 2L, 2L, 2L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 1L,
1L, 1L, 1L, 2L, 2L, 2L, 2L), .Label = c("1", "2"), class = "factor"),
EventType = structure(c(1L, 1L, 1L, 1L, 2L, 2L, 2L, 1L, 1L,
1L, 1L, 2L, 2L, 2L, 2L, 2L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L
), .Label = c("A", "B"), class = "factor"), Param1 = c(0.3,
0.21, 0.87, 0.78, 0.9, 1.2, 1.4, 1.3, 0.6, 0.45, 0.45, 0.04,
0, 0.1, 0.03, 0.01, 0.09, 0.06, 0.08, 0.09, 0.03, 0.04, 0.04,
0.02), Param2 = c(45, 38, 76, 32, 67, 23, 27, 784, 623, 54,
54, 1056, 487, 341, 671, 859, 7769, 2219, 4277, 4060, 411,
440, 224, 57), Param3 = c(1.5, 1.7, 1.65, 1.32, 0.6, 0.3,
2.5, 0.4, 1.4, 0.67, 0.67, 0.32, 0.1, 0.15, 0.22, 0.29, 0.3,
0.2, 0.8, 1, 0.9, 0.8, 0.3, 0.1), Param4 = c(0.14, 0, 1,
0.86, 0, 0.6, 1, 1, 0.18, 0, 0, 0.39, 0, 1, 0.29, 0.07, 0.33,
0.53, 0.29, 0.23, 0.84, 0.61, 0.57, 0.59), Param5 = c(0.18,
0, 1, 0, 1, 0, 0.09, 1, 0.78, 0, 0, 1, 0.2, 0, 0.46, 0.72,
0.16, 0.22, 0.77, 0.52, 0.2, 0.68, 0.58, 0.17), Param6 = c(0,
1, 0.75, 0, 0.14, 0, 1, 0, 1, 0.27, 0, 1, 0, 0.23, 0.55,
0.86, 1, 0.33, 1, 1, 0.88, 0.75, 0, 0), AbsoluteTime = structure(c(1522533600,
1522533602, 1522533604, 1522533604, 1525125600, 1525125602,
1525125604, 1519254000, 1519254002, 1519254004, 1519254006,
1521759600, 1521759602, 1521759604, 1521759606, 1521759608,
1517353224, 1517353226, 1517353228, 1517353230, 1517439600,
1517439602, 1517439604, 1517439606), class = c("POSIXct",
"POSIXt"), tzone = "")), row.names = c(NA, -24L), class = "data.frame")
df
The real data has 20 subject, EventNumbers ranging from 1 to 100, and parameters are from Param1 to Param40 (depending on the experiment).
Row number are around 60 000 observation.
- What I want to achieve:
For df, create n * 40 new columns. # (40 or any number of parameters that will be chosen later.)
Think of n as "steps into the future".
Name the 40 * n newly created columns:
Param1_2, Param2_2, Param3_2, ..., Param39_2, Param40_2, ...,
Param1_3, Param2_3, Param3_3, ..., Param39_3, Param40_3, ...,
...,
Param1_n, Param2_n, Param3_n, ..., Param39_n, Param40_n
Resulting in columns
Param1_1, Param2_1, Param1_2, Param2_2, Param1_3, Param2_3, Param1_4, Param2_4, ... Param1_n, Param2_n
So every observation of subset df[X, c(4:9)] will get an additional set of variables with values from df[X+1, c(4:9)] to df[X+n, c(4:9)].
This is what the new df.extended should look like for n = 1:
df.extended <- structure(list(SubjectID = c(1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2,
2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3), EventNumber = c(1, 1,
1, 1, 2, 2, 2, 1, 1, 1, 1, 2, 2, 2, 2, 2, 1, 1, 1, 1, 2, 2, 2,
2), EventType = c("A", "A", "A", "A", "B", "B", "B", "A", "A",
"A", "A", "B", "B", "B", "B", "B", "A", "A", "A", "A", "B", "B",
"B", "B"), Param1 = c(0.3, 0.21, 0.87, 0.78, 0.9, 1.2, 1.4, 1.3,
0.6, 0.45, 0.45, 0.04, 0, 0.1, 0.03, 0.01, 0.05, 0.07, 0.06,
0.01, 0.01, 0.01, 0.07, 0.04), Param2 = c(45, 38, 76, 32, 67,
23, 27, 784, 623, 54, 54, 1056, 487, 341, 671, 859, 1858, 640,
8181, 220, 99, 86, 170, 495), Param3 = c(1.5, 1.7, 1.65, 1.32,
0.6, 0.3, 2.5, 0.4, 1.4, 0.67, 0.67, 0.32, 0.1, 0.15, 0.22, 0.29,
1.5, 0.9, 0.8, 0.9, 0.1, 0, 0.8, 0.1), Param4 = c(0.14, 0, 1,
0.86, 0, 0.6, 1, 1, 0.18, 0, 0, 0.39, 0, 1, 0.29, 0.07, 0.64,
0.11, 0.12, 0.32, 0.55, 0.67, 0.83, 0.82), Param5 = c(0.18, 0,
1, 0, 1, 0, 0.09, 1, 0.78, 0, 0, 1, 0.2, 0, 0.46, 0.72, 0.27,
0.14, 0.7, 0.67, 0.23, 0.44, 0.61, 0.76), Param6 = c(0, 1, 0.75,
0, 0.14, 0, 1, 0, 1, 0.27, 0, 1, 0, 0.23, 0.55, 0.86, 1, 0.56,
0.45, 0.5, 0, 0, 0.89, 0.11), AbsoluteTime = c("2018-04-01 00:00:00",
"2018-04-01 00:00:02", "2018-04-01 00:00:04", "2018-04-01 00:00:04",
"2018-05-01 00:00:00", "2018-05-01 00:00:02", "2018-05-01 00:00:04",
"2018-02-22 00:00:00", "2018-02-22 00:00:02", "2018-02-22 00:00:04",
"2018-02-22 00:00:06", "2018-03-23 00:00:00", "2018-03-23 00:00:02",
"2018-03-23 00:00:04", "2018-03-23 00:00:06", "2018-03-23 00:00:08",
"2018-01-31 00:00:24", "2018-01-31 00:00:26", "2018-01-31 00:00:28",
"2018-01-31 00:00:30", "2018-02-01 00:00:00", "2018-02-01 00:00:02",
"2018-02-01 00:00:04", "2018-02-01 00:00:06"), Param1_2 = c(0.21,
0.87, 0.78, NA, 1.2, 1.4, NA, 0.6, 0.45, 0.45, NA, 0, 0.1, 0.03,
0.01, NA, 0.07, 0.07, 0.08, NA, 0.09, 0.06, 0.01, NA), Param2_2 = c(38,
76, 32, NA, 23, 27, NA, 623, 54, 54, NA, 487, 341, 671, 859,
NA, 6941, 4467, 808, NA, 143, 301, 219, NA), Param3_2 = c(1.7,
1.65, 1.32, NA, 0.3, 2.5, NA, 1.4, 0.67, 0.67, NA, 0.1, 0.15,
0.22, 0.29, NA, 1, 1, 0.1, NA, 0.5, 1, 0.3, NA), Param4_2 = c(0,
1, 0.86, NA, 0.6, 1, NA, 0.18, 0, 0, NA, 0, 1, 0.29, 0.07, NA,
0.31, 0.16, 0.68, NA, 0.86, 0.47, 0.47, NA), Param5_2 = c(0,
1, 0, NA, 0, 0.09, NA, 0.78, 0, 0, NA, 0.2, 0, 0.46, 0.72, NA,
0.29, 0.26, 0.1, NA, 0.88, 0.86, 0.95, NA), Param6_2 = c(1, 0,
0, NA, 0, 1, NA, 1, 0.27, 0, NA, 0, 0.23, 0.55, 0.86, NA, 0.68,
0.66, 0, NA, 0.44, 1, 0.22, NA)), row.names = c(NA, 24L), class = "data.frame")
df.extended
How can this be solved without using loops, writing column indexes by hand etc.? Write a function for trial 2 and use doBy?
My thoughts and what I have done so far to solve this:
Trial 1:
Cycle through the SubjectIDs in a for-loop
In an inner for-loop, cycle through the EventNumber
In another inner for-loop, cycle through the rows
Get the first row by grabbing df[1, ] and save into df.temp
Merge df.temp with df[2, parameters] #
Merge merge df.temp with df[3, parameters] and so on
Save all resulting df.temps into df.final
Problems I ran into: Step 5:
df.temp <- df[1,]
df.temp <- merge(df.temp, df[2, !(colnames(df) == "AbsoluteTime")], by = c("SubjectID", "EventNumber", "EventType"))
df.temp <- merge(df.temp, df[3, !(colnames(df) == "AbsoluteTime")], by = c("SubjectID", "EventNumber", "EventType"))
df.temp <- merge(df.temp, df[4, !(colnames(df) == "AbsoluteTime")], by = c("SubjectID", "EventNumber", "EventType"))
Warning:
In merge.data.frame(df.temp, df[4, ], by = c("SubjectID", "EventNumber", :
column names ‘Param1.x’, ‘Param2.x’, ‘Param3.x’, ‘Param4.x’, ‘Param5.x’, ‘Param6.x’, ‘AbsoluteTime.x’, ‘Param1.y’, ‘Param2.y’,
‘Param3.y’, ‘Param4.y’, ‘Param5.y’, ‘Param6.y’, ‘AbsoluteTime.y’ are
duplicated in the result.
The column names are repeated, see the warning.
I can not figure out how to easily create the column names / rename the new columns based on a given column name and variable.
There must a better way than this:
n <- 3
names_vector <- c()
for (n in seq(from = c(1), to = n)) {
for (i in names(df[4:9])) {
names_vector <- c(names_vector, paste0(i, "_", c(n+1)))
}
}
names(df.temp)[c(4:9)] <- parameters
names(df.temp)[c(11:ncol(df.temp))] <- names_vector
names(df.temp)
Also, how do I prevent the last n-1 rows from breaking the script? This is a lot of work to do by hand and I think quite error prone!?
Trial 2:
Cycle through the SubjectIDs in a for-loop
In an inner for-loop, cycle through the EventNumber
Get all rows of parameters into a new data frame except the first row
Append a row with NAs
use cbind() to merge the rows
Repeat n times.
This is the code for one SubjectID and one EventNumber:
df.temp <- df[which(df$SubjectID == "1" & df$EventNumber == "1"), ]
df.temp2 <- df.temp[2:nrow(df.temp)-1, parameters]
df.temp2 <- rbind(df.temp2, NA)
df.temp <- cbind(df.temp, df.temp2)
df.temp2 <- df.temp[3:nrow(df.temp)-1, parameters]
df.temp2 <- rbind(df.temp2, NA, NA)
df.temp <- cbind(df.temp, df.temp2)
df.temp2 <- df.temp[4:nrow(df.temp)-1, parameters]
df.temp2 <- rbind(df.temp2, NA, NA, NA)
df.temp <- cbind(df.temp, df.temp2)
n <- 3
names_vector <- c()
for (n in seq(from = c(1), to = n)) {
for (i in names(df[4:9])) {
print(i)
print(n)
names_vector <- c(names_vector, paste0(i, "_", c(n+1)))
}
}
names(df.temp)[c(4:9)] <- parameters
names(df.temp)[c(11:ncol(df.temp))] <- names_vector
df.temp
That solves the problem with missing rows (NAs are acceptable in my case).
Still lots of work by hand / for loops and error prone!?

Answer 1

What about something like this:
You can use the developer version of the package dplyr to add and rename variables according to various subsets of interest in your data. dplyr also provides the functions lead()and lag(), which can be used to find the "next" or "previous" values in a vector (or here row). You can use lead() in combination with the function mutate_at() to extract the values from the succeeding "nth"-row and use them to create new set of variables.
Here I use the data you provided in your example:
# load dplyr package
require(dplyr)
# creacte new data frame "df.extended"
df.extended <- df
# number of observations per group (e.g., SubjectID)
# or desired number of successions
obs = 3
# loop until number of successions achieved
for (i in 1:obs) {
# overwrite df.extended with new information
df.extended <- df.extended %>%
# group by subjects and events
group_by(SubjectID, EventNumber) %>%
# create new variable for each parameter
mutate_at( vars(Param1:Param6),
# using the lead function
.funs = funs(step = lead),
# for the nth followning row
n = i) %>%
# rename the new variables to show the succession number
rename_at(vars(contains("_step")), funs(sub("step", as.character(i), .)))
}
This should roughly recreate the data you posted as desired result.
# Look at first part of "df.extended"
> head(df.extended)
# A tibble: 6 x 28
# Groups: SubjectID, EventNumber [2]
SubjectID EventNumber EventType Param1 Param2 Param3 Param4 Param5 Param6 AbsoluteTime Param1_1 Param2_1 Param3_1 Param4_1 Param5_1 Param6_1
<fct> <fct> <fct> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dttm> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
1 1 1 A 0.300 45. 1.50 0.140 0.180 0. 2018-04-01 00:00:00 0.210 38. 1.70 0. 0. 1.00
2 1 1 A 0.210 38. 1.70 0. 0. 1.00 2018-04-01 00:00:02 0.870 76. 1.65 1.00 1.00 0.750
3 1 1 A 0.870 76. 1.65 1.00 1.00 0.750 2018-04-01 00:00:04 0.780 32. 1.32 0.860 0. 0.
4 1 1 A 0.780 32. 1.32 0.860 0. 0. 2018-04-01 00:00:04 NA NA NA NA NA NA
5 1 2 B 0.900 67. 0.600 0. 1.00 0.140 2018-05-01 00:00:00 1.20 23. 0.300 0.600 0. 0.
6 1 2 B 1.20 23. 0.300 0.600 0. 0. 2018-05-01 00:00:02 1.40 27. 2.50 1.00 0.0900 1.00
# ... with 12 more variables: Param1_2 <dbl>, Param2_2 <dbl>, Param3_2 <dbl>, Param4_2 <dbl>, Param5_2 <dbl>, Param6_2 <dbl>, Param1_3 <dbl>,
# Param2_3 <dbl>, Param3_3 <dbl>, Param4_3 <dbl>, Param5_3 <dbl>, Param6_3 <dbl>

Answer 2

For base R, consider by to slice by SubjectID, EventNumber, and EventType, and run a merge using a helper group_num. And to run across a series of params, wrap by process in an lapply for list of dataframes that you chain merge on the outside for final merge with original dataframe:
df_list <- lapply(2:3, function(i) {
# BUILD LIST OF DATAFRAMES
by_list <- by(df, df[c("SubjectID", "EventNumber", "EventType")], FUN=function(sub){
sub$grp_num <- 1:nrow(sub)
row_less_sub <- transform(sub, AbsoluteTime=NULL, grp_num=grp_num-(i-1))
merge(sub, row_less_sub, by=c("SubjectID", "EventNumber", "EventType", "grp_num"),
all.x=TRUE, suffixes = c("", paste0("_", i)))
})
# APPEND ALL DATAFRAMES IN LIST
grp_df <- do.call(rbind, by_list)
grp_df <- with(grp_df, grp_df[order(SubjectID, EventNumber),])
# KEEP NEEDED COLUMNS
grp_df <- grp_df[c("SubjectID", "EventNumber", "EventType", "grp_num",
names(grp_df)[grep("Param[0-9]_", names(grp_df))])]
row.names(grp_df) <- NULL
return(grp_df)
})
# ALL PARAMS_* CHAIN MERGE
params_df <- Reduce(function(x,y) merge(x, y, by=c("SubjectID", "EventNumber", "EventType", "grp_num")), df_list)
# ORIGINAL DF AND PARAMS MERGE
df$grp_num <- ave(df$Param1, df$SubjectID, df$EventNumber, df$EventType,
FUN=function(x) cumsum(rep(1, length(x))))
final_df <- transform(merge(df, params_df, by=c("SubjectID", "EventNumber", "EventType", "grp_num")), grp_num=NULL)
Output
head(final_df, 10)
# SubjectID EventNumber EventType Param1 Param2 Param3 Param4 Param5 Param6 AbsoluteTime Param1_2 Param2_2 Param3_2 Param4_2 Param5_2 Param6_2 Param1_3 Param2_3 Param3_3 Param4_3 Param5_3 Param6_3
# 1 1 1 A 0.30 45 1.50 0.14 0.18 0.00 2018-03-31 17:00:00 0.21 38 1.70 0.00 0.00 1.00 0.87 76 1.65 1.00 1.00 0.75
# 2 1 1 A 0.21 38 1.70 0.00 0.00 1.00 2018-03-31 17:00:02 0.87 76 1.65 1.00 1.00 0.75 0.78 32 1.32 0.86 0.00 0.00
# 3 1 1 A 0.87 76 1.65 1.00 1.00 0.75 2018-03-31 17:00:04 0.78 32 1.32 0.86 0.00 0.00 NA NA NA NA NA NA
# 4 1 1 A 0.78 32 1.32 0.86 0.00 0.00 2018-03-31 17:00:04 NA NA NA NA NA NA NA NA NA NA NA NA
# 5 1 2 B 0.90 67 0.60 0.00 1.00 0.14 2018-04-30 17:00:00 1.20 23 0.30 0.60 0.00 0.00 1.40 27 2.50 1.00 0.09 1.00
# 6 1 2 B 1.20 23 0.30 0.60 0.00 0.00 2018-04-30 17:00:02 1.40 27 2.50 1.00 0.09 1.00 NA NA NA NA NA NA
# 7 1 2 B 1.40 27 2.50 1.00 0.09 1.00 2018-04-30 17:00:04 NA NA NA NA NA NA NA NA NA NA NA NA
# 8 2 1 A 1.30 784 0.40 1.00 1.00 0.00 2018-02-21 17:00:00 0.60 623 1.40 0.18 0.78 1.00 0.45 54 0.67 0.00 0.00 0.27
# 9 2 1 A 0.60 623 1.40 0.18 0.78 1.00 2018-02-21 17:00:02 0.45 54 0.67 0.00 0.00 0.27 0.45 54 0.67 0.00 0.00 0.00
# 10 2 1 A 0.45 54 0.67 0.00 0.00 0.27 2018-02-21 17:00:04 0.45 54 0.67 0.00 0.00 0.00 NA NA NA NA NA NA