I want to show choosen one in array

when i add new doktor button,shows me all doktor but i want to show just one button and chosen
doktor.php
< ion-item *ngFor=“let mdr of a_doktor | async”>
{{mdr.Name}}
</ion-item

doktor.ts
export class Doktor {

t_doktor:any;
a_doktor:Observable<Mdoktor[]>;

constructor(public navCtrl: NavController,
public navParams: NavParams,
public alertCtrl: AlertController,
public toastCtrl: ToastController,
private store: Store,
private mdoktorActions: MdoktorActions,
public loadingCtrl: LoadingController) {

this.a_doktor = this.store.select(state => state.adoktors);

}