How Does R's Ifelse Work with Character Data

How does R's ifelse work with character data?

+1 for using a data.frame named blarg.

To expand on what Ben said, factors are internally stored as integers so when you do something like this, R doesn't handle it the way you expect.

Take a look at str(blarg) in the steps of your code above.

You can either use stringsAsFactors=FALSE as Ben suggested, or make use of the factor:

ifelse(blarg$a!='bb', levels(blarg$a), 'ZZZ')

Or better yet, if you want to replace the levels of blarg$a that are 'bb', you can eliminate the ifelse statement altogether:

levels(blarg$a)[levels(blarg$a)=='bb'] <- 'ZZZ'

R if else with multiple conditions for character vectors with NAs

A tidyverse approach

library(tidyverse)
DATA %>%
    mutate_if(is.factor, as.character) %>%
    mutate(Col.B = if_else(Col.A %in% c("Yes", "yes", "No", "no"), Col.B, Col.A))
#             Col.A           Col.B
#1        Some Text       Some Text
#2  Some other text Some other text
#3              Yes           Green
#4               No            <NA>
#5               no            <NA>
#6             <NA>            <NA>
#7               No            <NA>
#8              Yes            Blue
#9              yes          Blue 2
#10            <NA>            <NA>
#11            <NA>            <NA>
#12            <NA>            <NA>

In base R using grepl

transform(DATA, Col.B = ifelse(
    grepl("([Yy]es|[Nn]o)", Col.A),
    as.character(Col.B), as.character(Col.A)))

or similar to the tidyverse approach using %in% with tolower (thanks @DJV)

transform(DATA, Col.B = ifelse(
    tolower(Col.A) %in% c("yes", "no"),
    as.character(Col.B), as.character(Col.A)))

Why ifelse with character statement is not working?

There are three changes to be made,

1. converting to character would be with deparse/substitute

2. if/else would be appropriate as ifelse requires all the arguments to be of same length

3. iris * 2 as an else option wouldn't work as the dataset includes a factor column as well. So, we need to multiply only those numeric columns

   my_fun <- function(x) {               
            x <- deparse(substitute(x))
            if(x == 'Species') {
                iris %>% 
                  select(all_of(x)) 
              } else {
                   iris  %>%
                    mutate(across(where(is.numeric), ~ .* 2))
            }
     }
   

-testing

my_fun(Species)
#       Species
#1       setosa
#2       setosa
#3       setosa
#4       setosa
#5       setosa
#6       setosa
#...
     

and if we pass another input

my_fun(hello)
#    Sepal.Length Sepal.Width Petal.Length Petal.Width    Species
#1           10.2         7.0          2.8         0.4     setosa
#2            9.8         6.0          2.8         0.4     setosa
#3            9.4         6.4          2.6         0.4     setosa
#4            9.2         6.2          3.0         0.4     setosa
#5           10.0         7.2          2.8         0.4     setosa
#6           10.8         7.8          3.4         0.8     setosa
# ...

Using ifelse() statements to get objects of different classes in R

ifelse requires all the arguments to be same length. Here, it is not the case. Therefore, we need if/else

if(is.data.frame(mtcars) ) get(mtcars__string_object) else NA

-ouptut

                  mpg cyl  disp  hp drat    wt  qsec vs am gear carb
Mazda RX4           21.0   6 160.0 110 3.90 2.620 16.46  0  1    4    4
Mazda RX4 Wag       21.0   6 160.0 110 3.90 2.875 17.02  0  1    4    4
Datsun 710          22.8   4 108.0  93 3.85 2.320 18.61  1  1    4    1
Hornet 4 Drive      21.4   6 258.0 110 3.08 3.215 19.44  1  0    3    1
Hornet Sportabout   18.7   8 360.0 175 3.15 3.440 17.02  0  0    3    2
Valiant             18.1   6 225.0 105 2.76 3.460 20.22  1  0    3    1
Duster 360          14.3   8 360.0 245 3.21 3.570 15.84  0  0    3    4
Merc 240D           24.4   4 146.7  62 3.69 3.190 20.00  1  0    4    2
Merc 230            22.8   4 140.8  95 3.92 3.150 22.90  1  0    4    2
Merc 280            19.2   6 167.6 123 3.92 3.440 18.30  1  0    4    4
Merc 280C           17.8   6 167.6 123 3.92 3.440 18.90  1  0    4    4
Merc 450SE          16.4   8 275.8 180 3.07 4.070 17.40  0  0    3    3
Merc 450SL          17.3   8 275.8 180 3.07 3.730 17.60  0  0    3    3
Merc 450SLC         15.2   8 275.8 180 3.07 3.780 18.00  0  0    3    3
Cadillac Fleetwood  10.4   8 472.0 205 2.93 5.250 17.98  0  0    3    4
Lincoln Continental 10.4   8 460.0 215 3.00 5.424 17.82  0  0    3    4
Chrysler Imperial   14.7   8 440.0 230 3.23 5.345 17.42  0  0    3    4
Fiat 128            32.4   4  78.7  66 4.08 2.200 19.47  1  1    4    1
Honda Civic         30.4   4  75.7  52 4.93 1.615 18.52  1  1    4    2
Toyota Corolla      33.9   4  71.1  65 4.22 1.835 19.90  1  1    4    1
Toyota Corona       21.5   4 120.1  97 3.70 2.465 20.01  1  0    3    1
Dodge Challenger    15.5   8 318.0 150 2.76 3.520 16.87  0  0    3    2
AMC Javelin         15.2   8 304.0 150 3.15 3.435 17.30  0  0    3    2
Camaro Z28          13.3   8 350.0 245 3.73 3.840 15.41  0  0    3    4
Pontiac Firebird    19.2   8 400.0 175 3.08 3.845 17.05  0  0    3    2
Fiat X1-9           27.3   4  79.0  66 4.08 1.935 18.90  1  1    4    1
Porsche 914-2       26.0   4 120.3  91 4.43 2.140 16.70  0  1    5    2
Lotus Europa        30.4   4  95.1 113 3.77 1.513 16.90  1  1    5    2
Ford Pantera L      15.8   8 351.0 264 4.22 3.170 14.50  0  1    5    4
Ferrari Dino        19.7   6 145.0 175 3.62 2.770 15.50  0  1    5    6
Maserati Bora       15.0   8 301.0 335 3.54 3.570 14.60  0  1    5    8
Volvo 142E          21.4   4 121.0 109 4.11 2.780 18.60  1  1    4    2

ifelse statement with string

double is of length 1

length(double)
#[1] 1

whereas

length(data$var1)
#[1] 10

while using ifelse it returns the value which is of same length as test as

double == "true"

returns a vector of length 1, hence you get only one value back which is the first value of calculation

2*data$var1[1]
#[1] 2

and this value is recycled across all values.

For ifelse to work for all value we need to somehow make the length equal

ifelse(rep(double == "true", length(data$var1)), 2*data$var1, NA)
#[1]  2  4  6  8 10 12 14 16 18 20

However, if you have only one value to compare it is better to use simple if/else instead of ifelse

data$var2 <- if (double == "true") 2*data$var1 else NA 

New character values based on date range using ifelse

I found the problem vue$Name <- ifelse(vue$Serial == "483689" && vue$Date >= "2019-8-23 10:00:00", "newname", vue$Name)

I was missing the second & and vue$ before Date

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