The coordinate system of a plot refers to the space on which the data is plotted. The coordinate system of a plot, together with the x and y position scale, determines the location of geoms.

Below are the available coordinate options:

`coord_cartesian`

: This is the default coordinate system (x horizontal from left to right, y vertical from bottom to top)`coord_flip`

: Flipped cartesian coordinate system (x vertical from bottom to top, y horizontal from left to right)`coord_trans`

: Used to to transform the coordinate system. We, i.e., substitute traditional axes with logarithmic axes and then present the values and statistics`coord_equal`

: Ensures the units are equally scaled on the x-axis and on the y-axis`coord_polar`

: Polar coordinate system; the x (or y) scale is mapped to the angle (theta)`coord_map`

: Various map projections

Most popular graphs such as line and bar charts are drawn using Cartesian coordinates.

### coord_cartesian

When we plot a chart, Cartesian Coordinates is the default coordinate system. For example, the following chart plots Duration of Credit on x-axis and Credit Amount on y-axis. The points are colors by the factor Loan.Quality.

```
g <- ggplot(df,aes(x=Duration.of.Credit..in.months.,y=Credit.amount,color=Loan.Quality))
g+geom_point()+geom_smooth()+coord_cartesian()
```

### coord_flip

By specifying coord_flip, it will still use the cartesian system, but flip the two axis.

```
g <- ggplot(df,aes(x=Duration.of.Credit..in.months.,y=Credit.amount,color=Loan.Quality))
g+geom_point()+geom_smooth()+coord_flip()
```

### Zooming In

We can use the coordinates layer to zoom in to a plot by setting limits. The various options are below:

`coord_cartesian(xlim = NULL, ylim = NULL, expand = TRUE)`

`xlim, ylim`

: Limits for the x and y axes.`expand`

: If TRUE, the default, adds a small expansion factor to the limits to ensure that data and axes don’t overlap. If FALSE, limits are taken exactly from the data or xlim/ylim

Let’s say we want to zoom in our plot to show the points where the Duration of credit is between 40 and 60. This can be done as follows:

```
g <- ggplot(df,aes(x=Duration.of.Credit..in.months.,y=Credit.amount,color=Loan.Quality))
g+geom_point()+geom_smooth()+coord_cartesian(c(40,60))
```

### Aspect Ratio

We can set the aspect ratio of a plot with `coord_fixed()`

or `coord_equal()`

. Both use `aspect = 1`

(1:1) as a default. For example, consider the following plot which plots Duration of Credit on x-axis and Age on y-axis.

```
g <- ggplot(df,aes(x=Duration.of.Credit..in.months.,y=Age.in.years,color=Loan.Quality))
g+geom_point()+geom_smooth()
```

We can add the coordinate coord_equal() to make the aspect ratio 1:1.

```
g <- ggplot(df,aes(x=Duration.of.Credit..in.months.,y=Age.in.years,color=Loan.Quality))
g+geom_point()+geom_smooth()+coord_equal()
```

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