Splitting text by "|" and populating a table

Returning to your dictionary idea, you might want a tag:value approach as might be had with write.dcf. My system is a different encoding that yours that make some things hard to test, or with your encoding lead to undesired results, though will likely work on your system. I make the assumption that 'habs.', 'banos' 'm2' are the basics, further entries are additional amenities, and each 'record' starts with 'habs.' Using your data:

# split1 <- strsplit(...
strsplit(unname(unlist(data)), '|', fixed = TRUE)
[[1]]
[1] "2 habs."  "2 baños"  "72 m²"    "Bajos"    "Ascensor"

[[2]]
[1] "3 habs."     "2 baños"     "110 m²"      "Ascensor"    "Calefacción"

These are our records and we want to append \n\n to each as record separator for .dcf

# split1 <- lapply(...
lapply(split1, function(x) c(x, '\n\n'))
[[1]]
[1] "2 habs."  "2 baños"  "72 m²"    "Bajos"    "Ascensor" "\n\n"    

[[2]]
[1] "3 habs."     "2 baños"     "110 m²"      "Ascensor"    "Calefacción"
[6] "\n\n"       

At the moment, the 'tags' are after the 'values', so we have to swap them:

# split1 <- sub(...
sub('(.*) (.*)', '\\2 \\1', unlist(split1))
 [1] "habs. 2"     "baños 2"     "m² 72"       "Bajos"       "Ascensor"   
 [6] "\n\n"        "habs. 3"     "baños 2"     "m² 110"      "Ascensor"   
[11] "Calefacción" "\n\n"        "habs. 3"     "m² 70"       "Planta 2ª"  
[16] "\n\n"

.dcf tag:value so replace ' ' with ':'

# split1 <- gsub(
gsub(' ', ':', split1)
 [1] "habs.:2"     "baños:2"     "m²:72"       "Bajos"       "Ascensor"   
 [6] "\n\n"        "habs.:3"     "baños:2"     "m²:110"      "Ascensor"   
[11] "Calefacción" "\n\n"

We're close at this point, but I'm pretty sure that our un-terminated amenities (Bajos, Ascensor & etc) will be seen as 'malformed', though appears to work with cat

cat(split1)
habs.:2
baños:2
m²:72
Bajos
Ascensor
# but
c(read.dcf(textConnection(split1)))
Error in read.dcf(textConnection(split1)) : 
  Line starting 'Bajos ...' is malformed! # first non ':' terminated

Append ':', plays poorly with my encoding, but should work for yours, my bad results below

cat(gsub("(\\p{L}+)\\b(?![\\p{P}\\p{S}])", '\\1:', split1, perl = TRUE))
habs.:2
 bañ:os:2
 m:²:72
 Bajos:
 Ascensor:

Bad things happen to 'banos' and 'm2'. And perhaps it's all just a bad idea... But, changing the enyey in banos and exponent in m2, things start to get better, but the amenities need either a number or double listing (Ascensor Ascensor)

data$cardCharacteristics[6] <- "3 habs.|2 banos|187 m2|4ª Planta"
split3 <- strsplit(unname(unlist(data)), '|', fixed = TRUE)
split3 <- lapply(split3, function(x) c(x, '\n\n'))
split3 <- sub('(.*) (.*)', '\\2 \\1', unlist(split3))
split3 <- gsub(' ', ':', split3)
split3 <- gsub("(\\p{L}+)\\b(?![\\p{P}\\p{S}])", '\\1:', split3, perl = TRUE)> split3
 [1] "habs.:2"      "banos:2"      "m2:72"        "Bajos:"       "Ascensor:"   
 [6] "\n\n"         "habs.:3"      "banos:2"      "m2:110"       "Ascensor:"   
[11] "Calefacción:" "\n\n"       

A different gsub/regex, also suggested Append ':', ignores internal to string encoding mismatches:

split5 <- strsplit(unname(unlist(data3)), '|', fixed = TRUE)
split5 <- lapply(split5, function(x) c(x, '\n\n'))
split5 <- sub('(.*) (.*)', '\\2 \\1', unlist(split5))
split5 <- gsub(' ', ':', split5)
nocolon <- !grepl(':', split5)
> split5[nocolon] <- paste0(split5[nocolon], ':')
> split5
 [1] "habs.:2"      "baños:2"      "m²:72"        "Bajos:"       "Ascensor:"   
 [6] "\n\n:"

We just have to gsub \n\n to \n\n

split5 <- gsub('\n\n:', '\n\n', split5)
split5_df <- data.frame(read.dcf(textConnection(split5)))
split5_df
  habs. baños  m. Bajos Ascensor Calefacción Planta Terraza Balcón
1     2     2  72                       <NA>   <NA>    <NA>   <NA>
2     3     2 110  <NA>                        <NA>    <NA>   <NA>
3     3  <NA>  70  <NA>     <NA>        <NA>     2ª    <NA>   <NA>
4     2     2 160  <NA>     <NA>        <NA>   <NA>               
5     5     2 176  <NA>                 <NA>     7ª    <NA>   <NA>
6     3     2 187  <NA>     <NA>        <NA>     4ª    <NA>   <NA>

split5_df$Ascensor[which(split5_df$Ascensor == '')] <- c('old','new','scary')

split5_df$Calefacción[which(split5_df$Calefacción == '')] <- 'elec'

And we haven't seen piscina yet, but .dcf will know.

You were very close indeed, just the way you extracted Floorwas contrary to your aim (the lookahead prevented the extraction of the ª Plantasubstring!):

data %>% 
  mutate(
    habs = str_extract(cardCharacteristics, "(\\d)+(?= habs.)"),
    baños = str_extract(cardCharacteristics, "(\\d)+(?= baños)"),
    mts2 = str_extract(cardCharacteristics, "(\\d)+(?= m²)"),
    Terraza = str_extract(cardCharacteristics, "Terraza"),
    Calefacción = str_extract(cardCharacteristics, "Calefacción"),
    Floor = str_extract(cardCharacteristics, "Bajos|\\d+ª Planta"),  # <--- Corrected here
  )
                          cardCharacteristics habs baños mts2 Terraza Calefacción     Floor
1        2 habs.|2 baños|72 m²|Bajos|Ascensor    2     2   72    <NA>        <NA>     Bajos
2 3 habs.|2 baños|110 m²|Ascensor|Calefacción    3     2  110    <NA> Calefacción      <NA>
3                     3 habs.|70 m²|2ª Planta    3  <NA>   70    <NA>        <NA> 2ª Planta
4       2 habs.|2 baños|160 m²|Terraza|Balcón    2     2  160 Terraza        <NA>      <NA>
5   5 habs.|2 baños|176 m²|7ª Planta|Ascensor    5     2  176    <NA>        <NA> 7ª Planta
6            3 habs.|2 baños|187 m²|4ª Planta    3     2  187    <NA>        <NA> 4ª Planta

This is probably solvable using the tidyr package. This could be a starting point for you. sep accepts regex, so you could maybe utilize your regex from the str_extract above.

  library(dplyr)
  library(tidyr)
  data %>% separate(cardCharacteristics,
   sep = "\\|",
   into = c(
     "habs", "baños", "m^2", "Floor",
     "Lift"
   )
 )  

Results in

habs   baños       m^2     Floor        Lift
1 2 habs. 2 baños     72 m²     Bajos    Ascensor
2 3 habs. 2 baños    110 m²  Ascensor Calefacción
3 3 habs.   70 m² 2ª Planta      <NA>        <NA>
4 2 habs. 2 baños    160 m²   Terraza      Balcón
5 5 habs. 2 baños    176 m² 7ª Planta    Ascensor
6 3 habs. 2 baños    187 m² 4ª Planta        <NA>