Transposing Factor Summaries: A Comprehensive Approach

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As data analysts, we often encounter the need to summarize categorical data, such as factor variables. The summary() function in R is an efficient way to achieve this, but sometimes, we want to display the results in a more human-friendly format, like a transposed table. In this article, we’ll explore various approaches to print factor summaries in a “transposed” way.

Introduction

The problem at hand involves displaying the count of each level of a factor variable in a neat and compact manner, without any side effects. We can use R’s built-in functions, such as summary(), as.data.frame(), table(), and write.table() to achieve this.

Using `summary()`

One simple approach is to use the summary() function itself. However, the output is not immediately transposed:

h <- rnorm(100, 170, 10)
hf <- cut(h, breaks=10)

summary(hf)

Output:

(142,147]    5
(147,153]    3
(153,158]    7
(158,163]   20
(163,169]   11
(169,174]   23
(174,180]   12
(180,185]   11
(185,190]    6
(190,196]    2

We can improve this output by hiding the column name using setNames().

Using `as.data.frame()`

Another approach is to convert the summary to a data frame using as.data.frame():

r <- as.data.frame(summary(hf))
colnames(r) <- ""
r

Output:

(142,147]  5
(147,153]  3
(153,158]  7
(158,163] 20
(163,169] 11
(169,174] 23
(174,180] 12
(180,185] 11
(185,190]  6
(190,196]  2

However, we still need to hide the column name.

Using `table()`

We can use table() to achieve a similar result:

as.data.frame(table(hf))

Output:

          hf Freq
1  (142,147]    5
2  (147,153]    3
3  (153,158]    7
4  (158,163]   20
5  (163,169]   11
6  (169,174]   23
7  (174,180]   12
8  (180,185]   11
9  (185,190]    6
10 (190,196]    2

However, we still need to hide the row names.

Using `write.table()`

We can use write.table() to achieve a transposed output:

write.table(as.data.frame(table(hf)), col.names=FALSE, row.names=FALSE)
"(142,147]" 5
"(147,153]" 3
"(153,158]" 7
"(158,163]" 20
"(163,169]" 11
"(169,174]" 23
"(174,180]" 12
"(180,185]" 11
"(185,190]" 6
"(190,196]" 2

However, this approach has limitations. If the factor levels have different lengths, the output becomes misaligned.

The Best Approach: Using `setNames()`

The most elegant solution is to use setNames() with as.data.frame(summary(hf)):

summary(hf)

Output:

(142,147]           5
(147,153]           3
(153,158]           7
(158,163]          20
(163,169]          11
(169,174]          23
(174,180]          12
(180,185]          11
(185,190]           6
(190,196]           2

This approach is clean, efficient, and compact. We can also wrap our code in a function to make it more reusable.

Conclusion

In conclusion, printing factor summaries in a “transposed” way can be achieved using various approaches in R. While each method has its limitations, setNames() with as.data.frame(summary(hf)) is the most elegant and efficient solution. By following this approach, we can create clean, readable, and compact outputs that meet our needs without any side effects.

Code

Here is the complete code example:

h <- rnorm(100, 170, 10)
hf <- cut(h, breaks=10)

summary(hf)

# Using setNames()
as.data.frame(summary(hf))
setNames(as.data.frame(summary(hf)), "")

# Using table()
as.data.frame(table(hf))

# Using write.table()
write.table(as.data.frame(table(hf)), col.names=FALSE, row.names=FALSE)

Last modified on 2023-07-27