How can I replace empty cells with NA in R? - html

Question

I'm new to R, and have been trying a bunch of examples but I couldn't get anything to change all of my empty cells into NA.
library(XML)
theurl <- "http://www.pro-football-reference.com/teams/sfo/1989.htm"
table <- readHTMLTable(theurl)
table
Thank you.

Answer 1

The result you get from readHTMLTable is giving you a list of two tables, so you need to work on each list element, which can be done using lapply
table <- lapply(table, function(x){
x[x == ""] <- NA
return(x)
})
table$team_stats
Player PF Yds Ply Y/P TO FL 1stD Cmp Att Yds TD Int NY/A 1stD Att Yds TD Y/A 1stD Pen Yds 1stPy
1 Team Stats 442 6268 1021 6.1 25 14 350 339 483 4302 35 11 8.1 209 493 1966 14 4.0 124 109 922 17
2 Opp. Stats 253 4618 979 4.7 37 16 283 316 564 3235 15 21 5.3 178 372 1383 9 3.7 76 75 581 29
3 Lg Rank Offense 1 1 <NA> <NA> 2 10 1 <NA> 20 2 1 1 1 <NA> 13 10 12 13 <NA> <NA> <NA> <NA>
4 Lg Rank Defense 3 4 <NA> <NA> 11 9 9 <NA> 25 11 3 9 5 <NA> 1 3 3 8 <NA> <NA> <NA> <NA>

Answer 2

You have a list of data.frames of factors, though the actual data is mostly numeric. Converting to the appropriate type with type.convert will automatically insert the appropriate NAs for you:
df_list <- lapply(table, function(x){
x[] <- lapply(x, function(y){type.convert(as.character(y), as.is = TRUE)});
x
})
df_list[[1]][, 1:18]
## Player PF Yds Ply Y/P TO FL 1stD Cmp Att Yds.1 TD Int NY/A 1stD.1 Att.1 Yds.2 TD.1
## 1 Team Stats 442 6268 1021 6.1 25 14 350 339 483 4302 35 11 8.1 209 493 1966 14
## 2 Opp. Stats 253 4618 979 4.7 37 16 283 316 564 3235 15 21 5.3 178 372 1383 9
## 3 Lg Rank Offense 1 1 NA NA 2 10 1 NA 20 2 1 1 1.0 NA 13 10 12
## 4 Lg Rank Defense 3 4 NA NA 11 9 9 NA 25 11 3 9 5.0 NA 1 3 3
Or more concisely but with a lot of packages,
library(tidyverse) # for purrr functions and readr::type_convert
library(janitor) # for clean_names
df_list <- map(table, ~.x %>% clean_names() %>% dmap(as.character) %>% type_convert())
df_list[[1]]
## # A tibble: 4 × 23
## player pf yds ply y_p to fl x1std cmp att yds_2 td int ny_a
## <chr> <int> <int> <int> <dbl> <int> <int> <int> <int> <int> <int> <int> <int> <dbl>
## 1 Team Stats 442 6268 1021 6.1 25 14 350 339 483 4302 35 11 8.1
## 2 Opp. Stats 253 4618 979 4.7 37 16 283 316 564 3235 15 21 5.3
## 3 Lg Rank Offense 1 1 NA NA 2 10 1 NA 20 2 1 1 1.0
## 4 Lg Rank Defense 3 4 NA NA 11 9 9 NA 25 11 3 9 5.0
## # ... with 9 more variables: x1std_2 <int>, att_2 <int>, yds_3 <int>, td_2 <int>, y_a <dbl>,
## # x1std_3 <int>, pen <int>, yds_4 <int>, x1stpy <int>