# R – Exercise V

1) Use ifelse() and your data frame df from exercise IV: If the person is less than or equal to 175 cm, it should have the attribute “small”, otherwise “tall”. Save the result in your df as the new column size.category.

```x <- ifelse(df\$size <= 175, "small", "tall")

x
## [1] "small" "small" "tall" "tall" "small"

df\$size.categorie <- x

df
##    name age size    city weight size.categorie
## 1  Anna  66  170 Hamburg  115.0          small
## 2  Otto  53  174  Berlin  110.2          small
## 3 Natan  22  182  Berlin   95.0          tall
## 4   Ede  36  180 Cologne   87.0          tall
## 5  Anna  32  174 Hamburg   63.0          small
```

2) Write a loop that outputs all integers from 5 to 15!

```vektor <- 5:15
vektor
##  [1]  5  6  7  8  9 10 11 12 13 14 15

for (i in vektor) {
print(i)
}
## [1] 5
## [1] 6
## [1] 7
## [1] 8
## [1] 9
## [1] 10
## [1] 11
## [1] 12
## [1] 13
## [1] 14
## [1] 15
```

3) Advanced: Create a for loop that outputs the arithmetic mean for each variable (column) of your data frame df – provided that the variable is numeric!

```for (i in 1:ncol(df)) {

if (class(df[[i]]) == "numeric") {
print(names(df)[i])
result <- mean(df[[i]], na.rm=TRUE)
print(result)
}

}
## [1] "age"
## [1] 41.8
## [1] "size"
## [1] 176
## [1] "weight"
## [1] 94.04

# Even if it looks complicated, take your time and go through it line by line. Everything should be known by now!
```