# histogram: A histogram In psyntur: Helper Tools for Teaching Statistical Data Analysis

## Description

This is a wrapper to the typical `ggplot` based histogram, i.e., using `geom_histogram`. A continuous variable, `x`, is required as an input. Optionally, a `by` categorical variable can be provided.

## Usage

 ``` 1 2 3 4 5 6 7 8 9 10 11 12``` ```histogram( x, data, by = NULL, position = "stack", facet = NULL, facet_type = "wrap", bins = 10, alpha = 1, xlab = NULL, ylab = NULL ) ```

## Arguments

 `x` The numeric variable that is to be histogrammed. `data` A data frame with at least one numeric variable (the `x` variable). `by` A categorical variable by which to group the `x` values. If provided there will be one histogram for each set of `x` values grouped by the values of the `by` variable. `position` If the `by` variable is provided, there are three ways these multiple histograms can be positioned: stacked (`position = 'stack'`), side by side (`position = 'dodge'`), superimposed (`position = identity'`). `facet` A character string or character vector. If provided, we `facet_wrap` (by default) the histogram by the variables. This is equivalent to the `facet_wrap(variables)` in `ggplot2`. `facet_type` By default, this takes the value of `wrap`, and `facet` leads to a facet wrap. If `facet_type` is `grid`, then `facet` gives us a `facet_grid`. `bins` The number of bins to use in the histogram. `alpha` The transparency to for the filled histogram bars. This is probably only required when using `position = 'identity'`. `xlab` The label of the x-axis (defaults to the `x` variable name). `ylab` The label of the y-axis (defaults to the `y` variable name).

## Value

A `ggplot2::ggplot` object, which may be modified with further `ggplot2` commands.

## Examples

 ```1 2 3 4 5 6``` ```histogram(x= age, data = schizophrenia, by = gender, bins = 20) histogram(x= age, data = schizophrenia, by = gender, position = 'identity', bins = 20, alpha = 0.7) histogram(x= age, data = schizophrenia, by = gender, position = 'dodge', bins = 20) histogram(x = weight, bins = 20, data = ansur, facet = height_tercile) histogram(x = weight, bins = 20, data = ansur, facet = c(height_tercile, age_tercile), facet_type = 'grid') ```

psyntur documentation built on Sept. 15, 2021, 5:07 p.m.