imu: Create an IMU Object
In gmwm: Generalized Method of Wavelet Moments

Description Usage Arguments Details Value Author(s) Examples

Builds an IMU object that provides the program with gyroscope, accelerometer, and axis information per column in the dataset.

1 2	imu(data, gyros = NULL, accels = NULL, axis = NULL, freq = NULL, unit = NULL, name = NULL)

`data`	A `vector` which contains data, or a `matrix` or `data.frame` which contains the data in each column.
`gyros`	A `vector` that contains the index of columns where gyroscope data (such as Gyro. X, Gyro. Y and Gyro. Z) is placed.
`accels`	A `vector` that contains the index of columns where accelerometer data (such as Accel. X, Accel. Y and Accel. Z) is placed.
`axis`	A `vector` that indicates the axises, such as 'X', 'Y', 'Z'.
`freq`	An `integer` that provides the frequency for the data.
`unit`	A `string` that contains the unit expression of the frequency. Default value is `NULL`.
`name`	A `string` that provides an identifier to the data. Default value is `NULL`.

data can be a numeric vector, matrix or data frame.

gyros and accels cannot be NULL at the same time, but it will be fine if one of them is NULL. Also, in order to plot the graph, the length of gyros and accels are restricted to be equal.

In axis, duplicate elements are not alowed. If one of parameters between gyros and accels is NULL, specify the axis for each column of data. Check example 1 for help. If both of them are not NULL, specify the axis only for one parameter (gyros or accels). Check example 3 for help.

axis will be automatically generated if there are less than or equal to 3 axises.

An imu object in the following attributes:

sensor: A vector that indicates whether data contains gyroscope sensor, accelerometer sensor, or both.
num.sensor: A vector that indicates how many columns of data are for gyroscope sensor and accelerometer sensor.
axis: Axis value such as 'X', 'Y', 'Z'.
freq: Observations per second.
unit: String representation of the unit.
name: Name of the dataset.

JJB, Wenchao

## Not run: 
if(!require("imudata")){
   install_imudata()
   library("imudata")
}

data(imu6)

# Example 1 - Only gyros
test1 = imu(imu6, gyros = 1:3, axis = c('X', 'Y', 'Z'), freq = 100)
df1 = wvar.imu(test1)
plot(df1)

# Example 2 - One gyro and one accelerometer
test2 = imu(imu6, gyros = 1, accels = 4, freq = 100)
df2 = wvar.imu(test2)
plot(df2)

# Example 3 - 3 gyros and 3 accelerometers
test3 = imu(imu6, gyros = 1:3, accels = 4:6, axis = c('X', 'Y', 'Z'), freq = 100)
df3 = wvar.imu(test3)
plot(df3)

# Example 4 - Custom axis
test4 = imu(imu6, gyros = 1:2, accels = 4:5, axis = c('A', 'B'), freq = 100)
df4 = wvar.imu(test4)
plot(df4)

## End(Not run)