Why R resets dataframe column after function call? - r

I made simple R script and run:
f <- data.frame(x = c(1,1))
f$y <- NA
test <- function(n) {
f$y[1] <- 1
print(f)
}
test(0)
print(f)
the result is
> test(0)
x y
1 1 1
2 1 NA
> print(f)
x y
1 1 NA
2 1 NA
>
I would expect in the final output (1, 1) (1, NA) but for some reason f$y[1] had been reset to NA.
When I inline the function, the result are ok.
Why function call has this side effect on dataframe column?
Is it avoidable?

How about this:
f <- data.frame(x = c(1,1))
f$y <- NA
test <- function(f) {
f$y[1] <- 1
return(f)
}
f <- test(f)
print(f)
x y
1 1 1
2 1 NA

Related

Finding all sum of 2 power value combination values of a given number in R

R data frame 1 :
Index
Powervalue
0
1
1
2
2
4
3
8
4
16
5
32
R dataframe 2 :
CombinedValue
20
50
Expected Final Result :
Can we get the output as in the image. If yes please help.
One of stackoverflow mate provided below code. Am looking how to seperate , values as columns with 1 and 0.
df <- data.frame(sum = c(50, 20, 6))
values_list <- list()
for (i in 1:nrow(df)) {
sum <- df$sum[i]
values <- c()
while (sum > 0) {
value <- 2^floor(log2(sum))
values <- c(values, value)
sum <- sum - value
}
values_list[[i]] <- values
}
df$values <- values_list
Can we fix columns till power 31 as shown in attached image. The columns match with possiblecodes then place 1 and 0 else 0 for the remaining columns. Please help.
Here is a function whose output matches the expected output.
toCodes <- function(x) {
n <- floor(log2(x))
pow <- rev(seq.int(max(n)))
# 'y' is the matrix of codes
y <- t(sapply(x, \(.x) (.x %/% 2^pow) %% 2L))
i_cols <- apply(y, 2, \(.y) any(.y != 0L))
colnames(y) <- sprintf("code_%d", 2^pow)
#
possiblecodes <- apply(y, 1, \(p) {
codes <- 2^pow[as.logical(p)]
paste(rev(codes), collapse = ",")
})
data.frame(combinedvalue = x, possiblecodes, y[, i_cols])
}
x <- c(20L, 50L)
toCodes(x)
#> combinedvalue possiblecodes code_32 code_16 code_4 code_2
#> 1 20 4,16 0 1 1 0
#> 2 50 2,16,32 1 1 0 1
Created on 2022-12-19 with reprex v2.0.2

Summing Multiple Times in a Column

I have a dataframe, df, of two columns, x and y. I am trying to sum values within column y and put the sums into another dataframe. The summing only occurs for a section of column y between NA values. There are multiple sections of column y that must be summed but I want each sum to be a separate value in the new data frame.
df <- data.frame(x = c(1966,0.1,0.2,0.3,0.4,5622,0.9,0.8,0.7,0.6,7889),
y = c(NA,1,2,3,4,NA,9,8,7,6,NA))
The answer should be in the format of a data frame with one column of two rows:
df <- data.frame(x = c(10,30))
I thought of solving this using some for loop and if statements for values between values of NA in column y. Any ideas?
So far, I have the following code, but I ultimately want it to work for a column with a series of more than two summations:
NAs <- which(is.na(df$y))
L1 <- length(NAs)
L0 <- dim(df)[1]
soln1 <- data.frame(matrix(nrow = L1-1, ncol = 1))
for(i in 1:L0){
for(j in 1:L1){
if (j == L1){
break
} else
soln1[j,1] <- sum(df[NAs[j] +1,2]:df[NAs[j+1] -1,2])
}
}
I took a stab at it with some fake data:
df <- data.frame(x = c(1,1,3,1,3,1,1,1,1,1,3,1,1,1,1,1),
y = c(1,2,NA,4,5,NA,7,8,NA,10,11,NA,13,14,NA,16))
# df
# x y
#1 1 1
#2 1 2
#3 3 NA
#4 1 4
#5 3 5
#6 1 NA
#7 1 7
#8 1 8
#9 1 NA
#10 1 10
#11 3 11
#12 1 NA
#13 1 13
#14 1 14
#15 1 NA
#16 1 16
The magic function:
# sum rows in y if section is between NA values & before a value in column x that is > 2
specialSum <- function(x, y){
starting <- which(c(NA,x[-length(x)]) > 2 & is.na(y))
NAs <- which(is.na(y))
L <- length(starting)
ending <- sapply(1:L, function(z) NAs[NAs[-starting] > starting[z]][1])
output <- matrix(NA, nrow = L)
naming <- rep("",L)
for(i in 1:L){
output[i] <- sum(y[starting[i]:ending[i]], na.rm = T)
naming[i] <- paste0(starting[i]+1,":",ending[i]-1)
}
dimnames(output) <- list(naming, "specialSum")
output
}
specialSum(df$x, df$y)
# specialSum
#7:8 15
#13:14 27
EDIT:
df <- data.frame(x = c(1966,0.1,0.2,0.3,0.4,5622,0.9,0.8,0.7,0.6,7889),
y = c(NA,1,2,3,4,NA,9,8,7,6,NA))
specialSum <- function(y){
NAs <- which(is.na(y))
starting <- NAs[-length(NAs)]+1
ending <- NAs[-1]-1
L <- length(starting)
sums <- matrix(NA, nrow = L) ; naming <- rep("",L) # initialize for speed
for(i in 1:L){
sums[i] <- sum(y[starting[i]:ending[i]], na.rm = T)
naming[i] <- paste0(starting[i],":",ending[i])
}
sums <- sums[sums != 0,,drop = F] # in case there are multiple NAs in a row
data.frame(specialSum = sums, row.names = naming)
}
specialSum(df$y)
# specialSum
#2:5 10
#7:10 30
EDIT#2:
NAs <- which(is.na(df$y))
sumlist <- vector("list", length(NAs)-1)
count <- 0
for(i in 1:nrow(df)){
if(i %in% NAs){
count = count + 1
} else {
sumlist[[count]] <- append(sumlist[[count]], df$y[i])
}
}
data.frame(specialSum = unlist(lapply(sumlist, sum))) # less pretty output
# specialSum
#1 10
#2 30

How to add columns to data.frame based on vector length

I have a function runBootstrap whose output result is a vector of variable length (depending on # of values for cat, which itself is a product of test). Apologies that this isn't "minimal".
require(dplyr)
test <- function(combo) {
if(combo[1] == 4) {
cat <- 4
} else if((combo[1] == 3 & combo[2] == 2) | (combo[1] == 2 & combo[2] == 2)) {
cat <- 3
} else if((combo[1] == 2 & combo[2] == 1) | (combo[1] == 1 & combo[2] == 2)) {
cat <- 2
} else {
cat <- 1
}
}
arg1.freqs <- c(0.5, 0.2, 0.1, 0.1)
arg2.freqs <- c(0.8, 0.2)
runBootstrap <- function(arg1.freqs, arg2.freqs) {
sim.df <- data.frame(x1 = 1:10000, y1 = NA)
sim.df$x1 <- sample(1:4, 10000, replace = TRUE,
prob = arg1.freqs)
sim.df$y1 <- sample(1:2, 10000, replace = TRUE,
prob = arg2.freqs)
sim.df$cat <- NA
for(i in 1:nrow(sim.df)) {
combo <- c(sim.df[i, 1], sim.df[i, 2])
sim.df$cat[i] <- test(combo)
}
sim.df <- sim.df %>%
select(cat) %>%
group_by(cat) %>%
summarise(n = n()) %>%
mutate(freq = n / sum(n))
sim.df <- as.data.frame(sim.df)
result <- c(sim.df[1, 3], sim.df[2, 3])
}
In this current version there are only two values for cat so result is a vector of length 2; in a future version I will adjust code so that length(result) will equal # values of cat.
When using the function in a for loop, I would like to use the vector values to create new columns in an already existing data.frame df1. The code I've tried thus far is as follows:
df1$result <- NA
for (i in 1:nrow(df1)) {
df1$result[i] <- runBootstrap(arg1.freqs, arg2.freqs)
}
This clearly doesn't work unless the result vector is length = 1. But I don't know the length of the vector until the function runs (although once it runs it will be same length each iteration).
What I would like to achieve is the following:
Example 1: if length(result) == 2
df1.col x1 x2
1 1 1 1
2 2 2 2
3 3 3 3
4 4 4 4
5 5 5 5
6 6 6 6
Example 2: if length(result) == 3
df1.col x1 x2 x3
1 1 1 1 1
2 2 2 2 2
3 3 3 3 3
4 4 4 4 4
5 5 5 5 5
6 6 6 6 6
Thanks for any advice or direction.
edited for clarification
UPDATE - edited with solution
I got it to work as I wanted by creating a blank list, populating, then using rbind as follows:
appendResults <- function(df1, arg1, arg2) {
my.list <- vector("list", nrow(df1))
for (i in 1:nrow(df1)) {
arg1.freqs <- as.numeric(arg1[i, 3:6])
arg2.freqs <- as.numeric(arg2[i, 3:4])
my.list[[i]] <- runBootstrap(arg1.freqs, arg2.freqs)
}
result.df <- do.call(rbind, my.list)
df2 <- do.call(cbind, list(df1, result.df))
}
Check this one, not sure what the result looks like, but this creates empty columns, equal to the length of results, with NAs:
# fake data frame
df1 <- data.frame(x = c(1,2,3), y = c("a", "b", "c"))
# say result has length 3
res <- c(5,6,7)
# make columns with names x1, ..., x + length of res
# and assign NA values to those column
df1[ , paste("x", 1:length(res), sep = "")] <- NA

categorical variables shown as numeric instead as factors

I'm trying to create a random data set in R that has metric, binomial and categorical variables. However, in the end when I check the class of my categorical variables R says they are numeric, but I need them to be factors for my further analysis. Does anybody have an idea what I'm doing wrong here?
that's my code:
set.seed(3456)
R.dat <- function(n = 5000,metr=1,bin=1,cat=3) {
j <- metr
X <- (matrix(0,n,j))
for (i in 1:n) {
X[i,] <- rnorm(j, mean = 0, sd = 1)
}
BIN <- matrix(0,n,bin)
for (i in 1:bin) {
BIN[,i] <- rbinom(n,1, 0.5)
}
CAT <- matrix(0,n,cat)
for (i in 1:cat) {
CAT[,i] <- factor(sample(1:4, n, TRUE))
}
X <- as.data.frame(cbind(X,BIN, CAT))
return(X)
}
Dat <- R.dat(n=5000,metr=1,bin=1, cat=3)
summary(Dat)
If I just sample like this:
x <- factor(sample(1:4, n, TRUE))
class(x)
it says x is a factor, so I don't get why it doesn't do the same when I use it in the function and loop...any help is much apprecciated, thanks in advance!
When you do this:
CAT <- matrix(0,n,cat)
for (i in 1:cat) {
CAT[,i] <- factor(sample(1:4, n, TRUE))
}
you create a numeric matrix CAT, and then you assign a new value to a subset of that matrix. When you do that assignment, the new value is coerced to the type of CAT, which is numeric.
Also, when you cbind the matrices X, BIN and CAT at the end, you coerce all of them to a common type. This would again mess up your variable types, even assuming everything was working correctly up to this point.
The rest of your code can also be simplified considerably. In particular, you don't need looping to reassign values to matrices; you can call the matrix constructor function directly on a vector of values.
Try this instead:
R.dat <- function(n=5000, metr=1, bin=1, cat=3)
{
X <- matrix(rnorm(n * metr), nrow=n)
B <- matrix(rbinom(n * bin, 1, 0.5), nrow=n)
F <- matrix(as.character(sample(1:4, n * cat, TRUE)), nrow=n)
data.frame(X=X, B=B, F=F)
}
You don't need a loop, If you switch to data.table, you can generate them by reference.
library(data.table)
n <- 10
bin <- 1
DT <- data.table(X=replicate(n, rnorm(bin, mean=0, sd = 1)),
BIN = rbinom(n,1, 0.5),
CAT = factor(sample(1:4, n, TRUE)))
## If you need you can add more columns
cols <- paste0("CAT", 1:3)
DT[, (cols):= lapply(rep(n, 3) ,rbinom, 1, .5) ]
cols <- paste0("BIN", 1:3)
DT[, (cols):= lapply(rep(n, 3) ,function(x){factor(sample(1:4, n, TRUE)) }) ]
DT
lapply(DT, class)
DT
X BIN CAT CAT1 CAT2 CAT3 BIN1 BIN2 BIN3
1: 1.2934720 1 2 0 0 0 1 1 2
2: -0.1183180 1 2 0 0 1 3 3 1
3: 0.3648810 1 2 1 1 1 3 2 3
4: -0.2149963 1 2 1 1 0 2 3 2
5: 0.3204577 1 1 0 1 1 2 2 4
6: -0.5941640 0 4 1 0 0 2 3 1
7: -1.8852835 1 4 1 0 0 2 1 1
8: -0.8329852 0 2 0 0 1 1 1 2
9: -0.1353628 0 4 0 1 1 1 4 1
10: -0.2943969 1 4 0 1 0 4 3 3
> lapply(DT, class)
$X
[1] "numeric"
$BIN
[1] "integer"
$CAT
[1] "factor"
$CAT1
[1] "integer"
$CAT2
[1] "integer"
$CAT3
[1] "integer"
$BIN1
[1] "factor"
$BIN2
[1] "factor"
$BIN3
[1] "factor"
Because matrix does not accept factor vector, it will be coerced into numbers.
Just change it into a dataframe :
CAT <- matrix(0,n,cat)
CAT <- as.data.frame(CAT)
This will do the trick.

cbind: is there a way to have missing values set to NA?

Please forgive me if I missed an answer to such a simple question.
I want to use cbind() to bind two columns. One of them is a single entry shorter in length.
Can I have R supply an NA for the missing value?
The documentation discusses a deparse.level argument but this doesn't seem to be my solution.
Further, if I may be so bold, would there also be a quick way to prepend the shorter column with NA's?
Try this:
x <- c(1:5)
y <- c(4:1)
length(y) = length(x)
cbind(x,y)
x y
[1,] 1 4
[2,] 2 3
[3,] 3 2
[4,] 4 1
[5,] 5 NA
or this:
x <- c(4:1)
y <- c(1:5)
length(x) = length(y)
cbind(x,y)
x y
[1,] 4 1
[2,] 3 2
[3,] 2 3
[4,] 1 4
[5,] NA 5
I think this will do something similar to what DWin suggested and work regardless of which vector is shorter:
x <- c(4:1)
y <- c(1:5)
lengths <- max(c(length(x), length(y)))
length(x) <- lengths
length(y) <- lengths
cbind(x,y)
The code above can also be condensed to:
x <- c(4:1)
y <- c(1:5)
length(x) <- length(y) <- max(c(length(x), length(y)))
cbind(x,y)
EDIT
Here is what I came up with to address the question:
"Further, if I may be so bold, would there also be a quick way to prepend the shorter column with NA's?"
inserted into the original post by Matt O'Brien.
x <- c(4:1)
y <- c(1:5)
first <- 1 # 1 means add NA to top of shorter vector
# 0 means add NA to bottom of shorter vector
if(length(x)<length(y)) {
if(first==1) x = c(rep(NA, length(y)-length(x)),x);y=y
if(first==0) x = c(x,rep(NA, length(y)-length(x)));y=y
}
if(length(y)<length(x)) {
if(first==1) y = c(rep(NA, length(x)-length(y)),y);x=x
if(first==0) y = c(y,rep(NA, length(x)-length(y)));x=x
}
cbind(x,y)
# x y
# [1,] NA 1
# [2,] 4 2
# [3,] 3 3
# [4,] 2 4
# [5,] 1 5
Here is a function:
x <- c(4:1)
y <- c(1:5)
first <- 1 # 1 means add NA to top of shorter vector
# 0 means add NA to bottom of shorter vector
my.cbind <- function(x,y,first) {
if(length(x)<length(y)) {
if(first==1) x = c(rep(NA, length(y)-length(x)),x);y=y
if(first==0) x = c(x,rep(NA, length(y)-length(x)));y=y
}
if(length(y)<length(x)) {
if(first==1) y = c(rep(NA, length(x)-length(y)),y);x=x
if(first==0) y = c(y,rep(NA, length(x)-length(y)));x=x
}
return(cbind(x,y))
}
my.cbind(x,y,first)
my.cbind(c(1:5),c(4:1),1)
my.cbind(c(1:5),c(4:1),0)
my.cbind(c(1:4),c(5:1),1)
my.cbind(c(1:4),c(5:1),0)
my.cbind(c(1:5),c(5:1),1)
my.cbind(c(1:5),c(5:1),0)
This version allows you to cbind two vectors of different mode:
x <- c(4:1)
y <- letters[1:5]
first <- 1 # 1 means add NA to top of shorter vector
# 0 means add NA to bottom of shorter vector
my.cbind <- function(x,y,first) {
if(length(x)<length(y)) {
if(first==1) x = c(rep(NA, length(y)-length(x)),x);y=y
if(first==0) x = c(x,rep(NA, length(y)-length(x)));y=y
}
if(length(y)<length(x)) {
if(first==1) y = c(rep(NA, length(x)-length(y)),y);x=x
if(first==0) y = c(y,rep(NA, length(x)-length(y)));x=x
}
x <- as.data.frame(x)
y <- as.data.frame(y)
return(data.frame(x,y))
}
my.cbind(x,y,first)
# x y
# 1 NA a
# 2 4 b
# 3 3 c
# 4 2 d
# 5 1 e
my.cbind(c(1:5),letters[1:4],1)
my.cbind(c(1:5),letters[1:4],0)
my.cbind(c(1:4),letters[1:5],1)
my.cbind(c(1:4),letters[1:5],0)
my.cbind(c(1:5),letters[1:5],1)
my.cbind(c(1:5),letters[1:5],0)
A while back I had put together a function called Cbind that was meant to do this sort of thing. In its current form, it should be able to handle vectors, data.frames, and matrices as the input.
For now, the function is here: https://gist.github.com/mrdwab/6789277
Here is how one would use the function:
x <- 1:5
y <- letters[1:4]
z <- matrix(1:4, ncol = 2, dimnames = list(NULL, c("a", "b")))
Cbind(x, y, z)
# x y z_a z_b
# 1 1 a 1 3
# 2 2 b 2 4
# 3 3 c NA NA
# 4 4 d NA NA
# 5 5 <NA> NA NA
Cbind(x, y, z, first = FALSE)
# x y z_a z_b
# 1 1 <NA> NA NA
# 2 2 a NA NA
# 3 3 b NA NA
# 4 4 c 1 3
# 5 5 d 2 4
The two three functions required are padNA, dotnames, and Cbind, which are defined as follows:
padNA <- function (mydata, rowsneeded, first = TRUE) {
## Pads vectors, data.frames, or matrices with NA
temp1 = colnames(mydata)
rowsneeded = rowsneeded - nrow(mydata)
temp2 = setNames(
data.frame(matrix(rep(NA, length(temp1) * rowsneeded),
ncol = length(temp1))), temp1)
if (isTRUE(first)) rbind(mydata, temp2)
else rbind(temp2, mydata)
}
dotnames <- function(...) {
## Gets the names of the objects passed through ...
vnames <- as.list(substitute(list(...)))[-1L]
vnames <- unlist(lapply(vnames,deparse), FALSE, FALSE)
vnames
}
Cbind <- function(..., first = TRUE) {
## cbinds vectors, data.frames, and matrices together
Names <- dotnames(...)
datalist <- setNames(list(...), Names)
nrows <- max(sapply(datalist, function(x)
ifelse(is.null(dim(x)), length(x), nrow(x))))
datalist <- lapply(seq_along(datalist), function(x) {
z <- datalist[[x]]
if (is.null(dim(z))) {
z <- setNames(data.frame(z), Names[x])
} else {
if (is.null(colnames(z))) {
colnames(z) <- paste(Names[x], sequence(ncol(z)), sep = "_")
} else {
colnames(z) <- paste(Names[x], colnames(z), sep = "_")
}
}
padNA(z, rowsneeded = nrows, first = first)
})
do.call(cbind, datalist)
}
Part of the reason I stopped working on the function was that the gdata package already has a function called cbindX that handles cbinding data.frames and matrices with different numbers of rows. It will not work directly on vectors, so you need to convert them to data.frames first.
library(gdata)
cbindX(data.frame(x), data.frame(y), z)
# x y a b
# 1 1 a 1 3
# 2 2 b 2 4
# 3 3 c NA NA
# 4 4 d NA NA
# 5 5 <NA> NA NA

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