Transpose a data frame

Question

I need to transpose a large data frame and so I used:

df.aree <- t(df.aree)
df.aree <- as.data.frame(df.aree)

This is what I obtain:

df.aree[c(1:5),c(1:5)]
                         10428        10760        12148        11865
    name                M231T3       M961T5       M960T6      M231T19
    GS04.A        5.847557e+03 0.000000e+00 3.165891e+04 2.119232e+04
    GS16.A        5.248690e+04 4.047780e+03 3.763850e+04 1.187454e+04
    GS20.A        5.370910e+03 9.518396e+03 3.552036e+04 1.497956e+04
    GS40.A        3.640794e+03 1.084391e+04 4.651735e+04 4.120606e+04    

My problem is the new column names(10428, 10760, 12148, 11865) that I need to eliminate because I need to use the first row as column names.

I tried with col.names() function but I haven't obtain what I need.

Do you have any suggestion?

EDIT

Thanks for your suggestion!!! Using it I obtain:

df.aree[c(1:5),c(1:5)]
                        M231T3       M961T5       M960T6      M231T19
    GS04.A        5.847557e+03 0.000000e+00 3.165891e+04 2.119232e+04
    GS16.A        5.248690e+04 4.047780e+03 3.763850e+04 1.187454e+04
    GS20.A        5.370910e+03 9.518396e+03 3.552036e+04 1.497956e+04
    GS40.A        3.640794e+03 1.084391e+04 4.651735e+04 4.120606e+04
    GS44.A        1.225938e+04 2.681887e+03 1.154924e+04 4.202394e+04

Now I need to transform the row names(GS..) in a factor column....

Slick

Have you tried colnames(df.aree)<-df.aree[1,];df.aree<-df.aree[2:nrow(df.aree),]? – Thermistor

Data frames aren't naturally meant to be transposable. If yours is, then perhaps it should be in matrix form instead. – Burletta

Agree; ting data frame is also quite inefficient. If you can, use matrix. – Variorum

Transposing a data.frame that contains a string column in it turns ALL values into strings! NOT good. See my answer below for a work-around. – Debate

Answer 1

You'd better not transpose the data.frame while the name column is in it - all numeric values will then be turned into strings!

Here's a solution that keeps numbers as numbers:

# first remember the names
n <- df.aree$name

# transpose all but the first column (name)
df.aree <- as.data.frame(t(df.aree[,-1]))
colnames(df.aree) <- n
df.aree$myfactor <- factor(row.names(df.aree))

str(df.aree) # Check the column types

Debate

If you want to use transpose with data.frame, df <- df %>% mutate_if(is.character,as.numeric) can be used to change characters back to numeric. – Hemelytron

Answer 2

You can use the transpose function from the data.table library. Simple and fast solution that keeps numeric values as numeric.

library(data.table)

# get data
data("mtcars")

# transpose
t_mtcars <- transpose(mtcars)

# get row and colnames in order
colnames(t_mtcars) <- rownames(mtcars)
rownames(t_mtcars) <- colnames(mtcars)

Leinster

also, setnames(t_mtcars, rownames(mtcars)) would be the data.table-way of setting names on a data.table (and if using a data.table object you wouldn't set the rownames) – Jacquie

Also, within data.table::transpose you can use the arguments make.names to select the column (usually a character vector) whose names will become the column names for the transposed data.frame. You can also use the argument keep.names to choose a column name for the new column (a character vector) which will store the previous column names from the pre-transposed data.frame). – Daumier

Answer 3

df.aree <- as.data.frame(t(df.aree))
colnames(df.aree) <- df.aree[1, ]
df.aree <- df.aree[-1, ]
df.aree$myfactor <- factor(row.names(df.aree))

Tswana

@Slick If so, accept his answer by clicking a gray tick next to it. – Variorum

one problem with this - column names take the numeric representation of the factor level. – Macroclimate

Answer 4

With tidyr, one can transpose a dataframe with "pivot_longer" and then "pivot_wider".

To transpose the widely used mtcars dataset, you should first transform rownames to a column (the function rownames_to_column creates a new column, named "rowname").

library(tidyverse)

mtcars %>% 
rownames_to_column() %>% 
pivot_longer(!rowname, names_to = "col1", values_to = "col2") %>% 
pivot_wider(names_from = "rowname", values_from = "col2")

Caret

Answer 5

Take advantage of as.matrix:

# keep the first column 
names <-  df.aree[,1]

# Transpose everything other than the first column
df.aree.T <- as.data.frame(as.matrix(t(df.aree[,-1])))

# Assign first column as the column names of the transposed dataframe
colnames(df.aree.T) <- names

Bega

Answer 6

You can give another name for transpose matrix

df.aree1 <- t(df.aree)
df.aree1 <- as.data.frame(df.aree1)

Alexandro

As it’s currently written, your answer is unclear. Please edit to add additional details that will help others understand how this addresses the question asked. You can find more information on how to write good answers in the help center. – Sprightly