# R: How to Replace Values in Data Frame Conditionally

You can use one of the following methods to replace values in a data frame conditionally:

Method 1: Replace Values in Entire Data Frame

```#replace all values in data frame equal to 30 with 0
df[df == 30] <- 0
```

Method 2: Replace Values in Specific Column

```#replace values equal to 30 in 'col1' with 0
df\$col1[df\$col1 == 30] <- 0
```

Method 3: Replace Values in Specific Column Based on Another Column

```#replace values in col2 with 0 based on rows in col1 equal to 30
df\$col2[df\$col1 == 30] <- 0
```

The following examples show how to use each method in practice with the following data frame:

```#create data frame
df <- data.frame(team=c('A', 'A', 'B', 'B', 'B'),
points=c(99, 90, 90, 88, 88),
assists=c(33, 28, 31, 30, 34),
rebounds=c(30, 30, 24, 24, 28))

#view data frame
df

team points assists rebounds
1    A     99      33       30
2    A     90      28       30
3    B     90      31       24
4    B     88      30       24
5    B     88      34       28
```

### Method 1: Replace Values in Entire Data Frame

The following code shows how to replace all values equal to 30 in the data frame with 0:

```#replace all values in data frame equal to 30 with 0
df[df == 30] <- 0

#view updated data frame
df
team points assists rebounds
1    A     99      33        0
2    A     90      28        0
3    B     90      31       24
4    B     88       0       24
5    B     88      34       28
```

### Method 2: Replace Values in Specific Column

The following code shows how to replace all values equal to 90 in the ‘points’ column with 0:

```#replace all values equal to 90 in 'points' column with 0
df\$points[df\$points == 90] <- 0

#view updated data frame
df

team points assists rebounds
1    A     99      33       30
2    A      0      28       30
3    B      0      31       24
4    B     88      30       24
5    B     88      34       28
```

### Method 3: Replace Values in Specific Column Based on Another Column

The following code shows how to replace the values in the ‘points’ column with 0 where the value in the ‘team’ column is equal to ‘B.’

```#replace all values equal to 90 in 'points' column with 0
df\$points[df\$team == 'B'] <- 0

#view updated data frame
df

team points assists rebounds
1    A     99      33       30
2    A     90      28       30
3    B      0      31       24
4    B      0      30       24
5    B      0      34       28```