problems with Cycle for

Question

I’m with a rather simple doubt, but I haven’t figured out the solution yet. I have this df:

        High Low  Middle
current 0.51 0.43 0.22  
former  0.92 0.28 0.21  
never   0.78 0.22 0.9

and I wanted the values < 0.75 to stay NA.

I did this cycle:

for (element in ncol(df)) {
  df[which(df[element]< 0.75)] == "NA"
}

Does not replace values <0.75 by NA.

Answer 1

For this situation there is a simpler solution, just use the base::replace.

df1 <- data.frame(High = c(0.51, 0.92, 0.78),
                 Low  = c(0.43, 0.28, 0.22),
                 Middle = c(0.22, 0.21, 0.9),
                 nomes = c("current", "former", "never"))
library(tidyverse)
df2 <- df1 %>% 
  tibble::column_to_rownames("nomes")
df2

> df2
        High  Low Middle
current 0.51 0.43   0.22
former  0.92 0.28   0.21
never   0.78 0.22   0.90

df3 <- df2 %>% 
  base::replace(.<0.75, NA)
df3

> df3
        High Low Middle
current   NA  NA     NA
former  0.92  NA     NA
never   0.78  NA    0.9

---

If the for.

m <- matrix(nrow = nrow(df2), ncol = ncol(df2))

for (j in 1:ncol(m)) {
  for (i in 1:nrow(m)) {
    x <- ifelse(df2[i, j] < 0.75, NA, df2[i, j])
    m[i, j] <- x

  }
}

m

> m
     [,1] [,2] [,3]
[1,]   NA   NA   NA
[2,] 0.92   NA   NA
[3,] 0.78   NA  0.9

df4 <- m %>% 
  as.data.frame() %>% 
  dplyr::mutate(nomes = df1$nomes)
colnames(df4) <- colnames(df1)
df4 <- df4 %>% 
  tibble::column_to_rownames("nomes")
df4

> df4
        High Low Middle
current   NA  NA     NA
former  0.92  NA     NA
never   0.78  NA    0.9