get_trends {COINr} | R Documentation |

## Get time trends

### Description

Get time trends from a purse object. This function extracts a panel data set from a purse, and calculates trends
for each indicator/unit pair using a specified function `f_trend`

. For example, if `f_trend = "CAGR"`

, this extracts
the time series for each indicator/unit pair and passes it to `CAGR()`

.

### Usage

```
get_trends(
purse,
dset,
uCodes = NULL,
iCodes = NULL,
Time = NULL,
use_latest = NULL,
f_trend = "CAGR",
interp_at = NULL,
adjust_directions = FALSE
)
```

### Arguments

`purse` |
A purse object |

`dset` |
Name of the data set to extract, passed to |

`uCodes` |
Optional subset of unit codes to extract, passed to |

`iCodes` |
Optional subset of indicator/aggregate codes to extract, passed to |

`Time` |
Optional vector of time points to extract, passed to |

`use_latest` |
A positive integer which specifies to use only the latest "n" data points. If this is specified, it
overrides |

`f_trend` |
Function that returns a metric describing the trend of the time series. See details. |

`interp_at` |
Option to linearly interpolate missing data points in each time series. Must be specified as a vector
of time values where to apply interpolation. If |

`adjust_directions` |
Logical: if |

### Details

This function requires a purse object as an input. The data set is selected using `get_data()`

, such that a subset
of the data set can be analysed using the `uCodes`

, `iCodes`

and `Time`

arguments. The latter is useful especially
if only a subset of the time series should be analysed.

The function `f_trend`

is a function that, given a time series, returns a trend metric. This must follow a
specific format. It must of course be available to call, and *must* have arguments `y`

and `x`

, which are
respectively a vector of values and a vector indexing the values in time. See `prc_change()`

and `CAGR()`

for examples. The function *must* return a single value (not a vector with multiple entries, or a list).
The function can return either numeric or character values.

### Value

A data frame in long format, with trend metrics for each indicator/unit pair, plus data availability statistics.

### Examples

```
#
```

*COINr*version 1.1.14 Index]