Create some data

## Create some data ##

patient <- c('Randy', 'Anne', 'Sawyer', 'Taylor')
group <- c('testA', 'testA', 'testB', 'testB')
first_measure <- c(22, 24, 20, 20)
second_measure <- c(24, 22, 19, 18)
third_measure <- c(25, 21, 16, 15)
fourth_measure <- c(20, 19, 14, 12)

patient_data <- data.frame(patient, group, first_measure, second_measure, third_measure, fourth_measure)


patient_data

##   patient group first_measure second_measure third_measure fourth_measure
## 1   Randy testA            22             24            25             20
## 2    Anne testA            24             22            21             19
## 3  Sawyer testB            20             19            16             14
## 4  Taylor testB            20             18            15             12

data.table - Melt

library(data.table)
## Convert to data table
patient_data <- data.table(patient_data)

# Melt
patient_data <-  melt(patient_data, id=c("patient", "group"), measure=c("first_measure", "second_measure", "third_measure", "fourth_measure"), variable.name="measure", value.name='value')

patient_data

##     patient group        measure value
##  1:   Randy testA  first_measure    22
##  2:    Anne testA  first_measure    24
##  3:  Sawyer testB  first_measure    20
##  4:  Taylor testB  first_measure    20
##  5:   Randy testA second_measure    24
##  6:    Anne testA second_measure    22
##  7:  Sawyer testB second_measure    19
##  8:  Taylor testB second_measure    18
##  9:   Randy testA  third_measure    25
## 10:    Anne testA  third_measure    21
## 11:  Sawyer testB  third_measure    16
## 12:  Taylor testB  third_measure    15
## 13:   Randy testA fourth_measure    20
## 14:    Anne testA fourth_measure    19
## 15:  Sawyer testB fourth_measure    14
## 16:  Taylor testB fourth_measure    12