Merging data frames in R Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to merge two data frames by the column 'id'.

R Programming

merged_df <- merge(df1, df2, by = [1])

Drag options to blanks, or click blank then click option'

A"score"

B"name"

C"age"

D"id"

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to put the column name in quotes.

Using a column name that does not exist in both data frames.

The merge() function combines two data frames by matching values in the specified column. Here, we merge by the column named id.

2fill in blank

medium

Complete the code to perform a left join of df1 with df2 by 'id'.

R Programming

merged_df <- merge(df1, df2, by = "id", all.x = [1])

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ATRUE

BNA

CFALSE

DNULL

Attempts:

3 left

💡 Hint

Common Mistakes

Using FALSE instead of TRUE for all.x.

Confusing all.x with all.y.

Setting all.x = TRUE keeps all rows from df1 and adds matching rows from df2. This is a left join.

3fill in blank

hard

Fix the error in the code to merge df1 and df2 by columns 'id' and 'date'.

R Programming

merged_df <- merge(df1, df2, by = [1])

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Ac(id, date)

B"id, date"

Cc("id", "date")

Dlist("id", "date")

Attempts:

3 left

💡 Hint

Common Mistakes

Passing a single string with comma-separated names.

Using unquoted column names.

The by argument expects a character vector of column names. Use c("id", "date") to specify both columns.

4fill in blank

hard

Fill both blanks to merge df1 and df2 by 'id' and keep all rows from both data frames.

R Programming

merged_df <- merge(df1, df2, by = [1], all.x = [2], all.y = TRUE)

Drag options to blanks, or click blank then click option'

A"id"

BTRUE

CFALSE

D"date"

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong column name for merging.

Setting all.x to FALSE which drops rows from df1.

To merge by 'id' and keep all rows from both data frames, set by = "id", all.x = TRUE, and all.y = TRUE.

5fill in blank

hard

Fill all three blanks to merge df1 and df2 by 'id', keep all rows from df1, and suffix overlapping columns with '_df1' and '_df2'.

R Programming

merged_df <- merge(df1, df2, by = [1], all.x = [2], suffixes = c([3], "_df2"))

Drag options to blanks, or click blank then click option'

A"id"

BTRUE

C"_df1"

DFALSE

Attempts:

3 left

💡 Hint

Common Mistakes

Not using quotes around suffix strings.

Setting all.x to FALSE which drops rows from df1.

Using wrong column name for merging.

We merge by 'id', keep all rows from df1 with all.x = TRUE, and set suffixes to distinguish overlapping columns.