## Solution 1

```
select(variants, contains("i"), -Indiv, -FILTER, POS)
```

## Solution 2

```
filter(variants, POS >= 1e6 & POS <= 2e6, !INDEL, QUAL 200)
```

## Exercise 1 Solution

```
variants %>%
filter(sample_id == "SRR2584863" & DP >= 10) %>%
select(REF, ALT, POS)
```

## Exercise 2 Solution

```
variants %>%
mutate(POLPROB = 1 - 10 ^ -(QUAL/10)) %>%
select(sample_id, POS, QUAL, POLPROB)
```

## Challenge 3 Solution 3

```
variants_indel %>%
  group_by(mutation_type) %>%
  summarize(
    max_size = max(abs(indel_size))
  )
```

## Challenge 4 Solution

```
variants_indel %>%
  count(sample_id)
```

## Optional Challenge

## Solution

```
variants %>%
  mutate(POLPROB = 1 - (10 ^ -(QUAL/10))) %>%
  mutate(prob_cat = case_when(
    POLPROB >=  .95 ~ "high",
    POLPROB >=  .7 & POLPROB < .95 ~ "medium",
    POLPROB < .7 ~ "low"
  )) %>%
  count(sample_id, prob_cat) %>%
  spread(prob_cat, n)
```