diff --git a/example.py b/example.py
index 45fa4d1..487e5ba 100644
--- a/example.py
+++ b/example.py
@@ -7,6 +7,7 @@ tdxpath = b"samples/SineData.tdx"
 
 # create instance of ripper class
 RP = tdm_ripper.pytdmripper(tdmpath)
+RP = tdm_ripper.pytdmripper(b"/Users/mariofink/git/Conti_HBS/data_science/python/features/tdm_tmp_slow/75_1/Messung.tdm")
 
 # provide overview of available channels
 RP.show_channels()
@@ -14,27 +15,30 @@ RP.show_channels()
 print(RP.num_channels())
 print(RP.num_groups())
 
+for i in range(0,RP.num_groups()):
+    print(str(i+1).rjust(10)+str(RP.no_channels(i)).rjust(10))
+
 # print particular channel to file
-RP.print_channel(1,b"SineData_extract.dat")
+# RP.print_channel(1,b"SineData_extract.dat")
 
 # extract channel and return it to numpy array
-channels = RP.get_channel(1)
-Nlen = len(channels)
-channels = np.append(channels,RP.get_channel(2))
-channels = np.append(channels,RP.get_channel(3))
-channels = np.append(channels,RP.get_channel(4))
-channels = np.append(channels,RP.get_channel(5))
-channels = np.append(channels,RP.get_channel(6))
-channels = np.append(channels,RP.get_channel(7))
-channels = np.append(channels,RP.get_channel(8))
-print(channels.shape)
-print("\n\n")
-print(channels[0:40])
-
-x = np.linspace(0,Nlen,Nlen)
-plt.plot(x,channels[0:Nlen])
-plt.plot(x,channels[Nlen:2*Nlen])
-plt.plot(x,channels[2*Nlen:3*Nlen])
-
-plt.grid()
-plt.show()
+# channels = RP.get_channel(1)
+# Nlen = len(channels)
+# channels = np.append(channels,RP.get_channel(2))
+# channels = np.append(channels,RP.get_channel(3))
+# channels = np.append(channels,RP.get_channel(4))
+# channels = np.append(channels,RP.get_channel(5))
+# channels = np.append(channels,RP.get_channel(6))
+# channels = np.append(channels,RP.get_channel(7))
+# channels = np.append(channels,RP.get_channel(8))
+# print(channels.shape)
+# print("\n\n")
+# print(channels[0:40])
+#
+# x = np.linspace(0,Nlen,Nlen)
+# plt.plot(x,channels[0:Nlen])
+# plt.plot(x,channels[Nlen:2*Nlen])
+# plt.plot(x,channels[2*Nlen:3*Nlen])
+#
+# plt.grid()
+# plt.show()
diff --git a/lib/tdm_ripper.cpp b/lib/tdm_ripper.cpp
index 8eb27ec..c6b6a0f 100644
--- a/lib/tdm_ripper.cpp
+++ b/lib/tdm_ripper.cpp
@@ -209,6 +209,10 @@ void tdm_ripper::parse_structure()
   assert( num_channels_ == (int)channel_id_.size()
        && num_channels_ == (int)channel_name_.size()
        && num_channels_ == (int)channels_group_.size() );
+
+  std::cout<<std::setw(25)<<std::left<<"number of channels:"<<std::setw(10)<<num_channels_<<"\n";
+  for ( int i = 0; i < num_groups_; i++ ) std::cout<<std::setw(25)<<std::left<<"group"<<std::setw(10)<<i+1<<std::setw(10)<<no_channels(i+1)<<"\n";
+  std::cout<<std::right<<"\n\n";
 }
 
 void tdm_ripper::list_channels(std::ostream& gout, int width, int maxshow)
diff --git a/lib/tdm_ripper.hpp b/lib/tdm_ripper.hpp
index b957e1e..149029a 100644
--- a/lib/tdm_ripper.hpp
+++ b/lib/tdm_ripper.hpp
@@ -148,6 +148,12 @@ public:
   {
     return num_groups_;
   }
+  const int& no_channels(int groupid)
+  {
+    assert( groupid > 0 && groupid <= num_channels_ );
+
+    return num_channels_group_[groupid-1];
+  }
 
   const std::string& channel_name(int channelid)
   {
diff --git a/main.cpp b/main.cpp
index 1c68800..75ffb8b 100644
--- a/main.cpp
+++ b/main.cpp
@@ -25,17 +25,22 @@ int main(int argc, char* argv[])
   std::cout<<"number of channels "<<ripper.num_channels()<<"\n\n";
   std::cout<<"number of groups "<<ripper.num_groups()<<"\n\n";
 
+  for ( int i = 0; i < ripper.num_groups(); i++ )
+  {
+    std::cout<<std::setw(10)<<i+1<<std::setw(10)<<ripper.no_channels(i+1)<<"\n";
+  }
+
   // std::vector<double> channA = ripper.get_channel(1);
   // for ( auto el: channA ) std::cout<<el<<"\n";
   // std::cout<<"\n\n";
 
-  for ( int i = 0; i < 30; i++ )
-  // for ( int i = 0; i < ripper.num_channels(); i++ )
-  // for ( int i = 11880; i < ripper.num_channels(); i++ )
-  {
-    ripper.print_channel(i+1,("data/channel_"+std::to_string(i+1)+"_"
-                                        +ripper.channel_name(i+1)+".dat").c_str());
-  }
+  // for ( int i = 0; i < 30; i++ )
+  // // for ( int i = 0; i < ripper.num_channels(); i++ )
+  // // for ( int i = 11880; i < ripper.num_channels(); i++ )
+  // {
+  //   ripper.print_channel(i+1,("data/channel_"+std::to_string(i+1)+"_"
+  //                                       +ripper.channel_name(i+1)+".dat").c_str());
+  // }
 
   return 0;
 }
diff --git a/makefile b/makefile
index c632677..12a5ff4 100644
--- a/makefile
+++ b/makefile
@@ -22,6 +22,9 @@ clean :
 pylib : setup.py pytdm_ripper.pyx tdm_ripper.pxd tdm_ripper.o
 	python3 setup.py build_ext --inplace
 
+install : setup.py pytdm_ripper.pyx tdm_ripper.pxd lib/tdm_ripper.cpp lib/tdm_ripper.hpp
+	python3 setup.py install
+
 lib/libtdmripper.a :
 	make -C lib libtdmripper.a
 
diff --git a/pytdm_ripper.pyx b/pytdm_ripper.pyx
index e9c4ebb..1922611 100644
--- a/pytdm_ripper.pyx
+++ b/pytdm_ripper.pyx
@@ -19,6 +19,11 @@ cdef class pytdmripper:
     def num_channels(self):
         return self.cripp.num_channels()
 
+    def no_channels(self, int groupid):
+        assert (groupid >= 0 and groupid < self.cripp.num_groups()), "index of group must be in [0,n-1]"
+        groupidinc = groupid+1
+        return self.cripp.no_channels(groupidinc)
+
     def num_groups(self):
         return self.cripp.num_groups()
 
diff --git a/tdm_ripper.pxd b/tdm_ripper.pxd
index 0d372b8..c0b229a 100644
--- a/tdm_ripper.pxd
+++ b/tdm_ripper.pxd
@@ -13,6 +13,7 @@ cdef extern from "tdm_ripper.hpp":
         tdm_ripper(string) except +
         void list_channels()
         int num_channels()
+        int no_channels(int)
         int num_groups()
         vector[double] get_channel(int)
         void print_channel(int,const char*)