Merge Two Unequal DataFrames and Replace NA with 0 in R

Last Updated : 29 Sep, 2021

In this article we are going to merge two unequal dataframes and then replace NA values in the resultant dataframe with 0 using R programming language.

Dataframes in use:

Merging the dataframes

We can merge the two dataframes by using merge() function.

Syntax:

merge(dataframe1, dataframe2, by = "column",all = TRUE)

where,

dataframe1 is the first dataframe
dataframe2 is the second dataframe
column is the column name to be merged based on this column

Example: R program to merge the dataframes by id column

# create dataframe1 with 3 columns
data1 = data.frame(id=c(1, 2, 3, 4, 5),
                   age=c(12, 23, 21, 23, 21),
                   marks=c(100, 90, 98, 87, 80))

# create dataframe2 with 3 columns
data2 = data.frame(id=c(3, 4, 5, 6, 7),
                   age=c(12, 23, 56, 67, 48),
                   marks=c(60, 90, 91, 87, 80))

# merge the dataframes by id column
data = merge(data1, data2, by='id', all=TRUE)

# display merged dataframe
print(data)

Output:

Replacing NA with 0 in dataframe

We can replace NA by using is.na() function. By setting data to 0 inside the index the job can be easily done.

Syntax:

data[is.na(data)] = 0

Where, data is the merged dataframe with NA values

Example: R program to replace NA with 0

# create dataframe1 with 3 columns
data1 = data.frame(id=c(1, 2, 3, 4, 5),
                   age=c(12, 23, 21, 23, 21),
                   marks=c(100, 90, 98, 87, 80))

# create dataframe2 with 3 columns
data2 = data.frame(id=c(3, 4, 5, 6, 7),
                   age=c(12, 23, 56, 67, 48),
                   marks=c(60, 90, 91, 87, 80))

# merge the dataframes by id column
data = merge(data1, data2, by='id', all=TRUE)

# display merged dataframe
print(data)

# Replace NA with 0
data[is.na(data)] = 0

print(data)