This is a short tutorial explaining how to perform photometric redshift estimation using the CosmoPhotoz R package.

Required libraries

```{r,results='hide',message=FALSE, cache=FALSE} require(CosmoPhotoz) require(ggplot2)


Load the PHAT0 data included in the package. Here we are using 5% of all dataset for training.

```{r} data(PHAT0train)

data(PHAT0test) ```

{r} PC_comb<-computeCombPCA(subset(PHAT0train,select=c(-redshift)), subset(PHAT0test,select=c(-redshift)))

Number of variance explained by each PC {r} PC_comb$PCsum

Add the redshift column to the PCA projections of the Training sample

```{r} Trainpc<-cbind(PC_combx, redshift = PHAT0trainredshift)


Store the PCA projections for the testing sample in the vector Testpc

{r, echo=FALSE} Testpc<-PC_comb$y

Train the glm model using Gamma Family. 6 PCs explain 99.5% of data variance. In order to account for small variations in the shape, we include a polynomial term for the 2 first PCs (95% of data variance)




Once we fit our GLM model, we can predict the redshift for the "photometric" sample

```{r, echo=FALSE}

photoz<-predict(Fit$glmfit,newdata = Testpc,type="response")


Store the redshift from the testing sample in the vector specz for comparison

{r, echo=FALSE} specz<-PHAT0test$redshift

Compute basic diagnostic statistics

{r, echo=FALSE} computeDiagPhotoZ(photoz, specz)

Create basic diagnostic plots

Kernel density distribution of the full scatter (specz − photoz)/(1 + specz)

```{r,fig.width=8, fig.height=9} plotDiagPhotoZ(photoz, specz, type = "errordist")


Predicted vs Actuall values Select 15,000 points to show {r} datashow<-sample(length(photoz),15000)

{r,fig.width=8, fig.height=9} plotDiagPhotoZ(photoz[datashow], specz[datashow], type = "predobs")+coord_cartesian(xlim =c(0,1.5), ylim = c(0,1.5))

Scatter distribution as a function of redshift, violin plot

{r,fig.width=12, fig.height=9} plotDiagPhotoZ(photoz, specz, type = "errorviolins")

Scatter distribution as a function of redshift, box plot

{r,fig.width=12, fig.height=9} plotDiagPhotoZ(photoz, specz, type = "box")

{r, echo=FALSE} shinyAppDir("paste(find.package("CosmoPhotoz"),"/glmPhotoZ-2/",sep=""))