diff --git a/src/mpMptcptraceData.py b/src/mpMptcptraceData.py
index 5b63763..e69eaeb 100644
--- a/src/mpMptcptraceData.py
+++ b/src/mpMptcptraceData.py
@@ -38,7 +38,7 @@ class MptcptraceData:
 
 	# gets cell corresponding to flow with header column 
 	# flow 0 = first one, from 1=subflows
-	def get(self, name):
+	def get_csv(self, name):
                 if hasattr(self,name):
                         return getattr(self,name)
                 else:
diff --git a/src/mpTcptraceData.py b/src/mpTcptraceData.py
index c2bdaf6..99fb2da 100755
--- a/src/mpTcptraceData.py
+++ b/src/mpTcptraceData.py
@@ -6,6 +6,7 @@ import csv
 
 from io import StringIO
 import re
+import numpy as np
 
 
 
@@ -15,43 +16,12 @@ class TcptraceData:
 		self.pcap_file=pcap_file
 		csv_content = check_output(["tcptrace", "-l", "--csv", pcap_file])
 		tcptrace_reader = csv.reader(filter(lambda l: len(l)>0 and l[0]!="#",csv_content.splitlines()))
-		cells=list(tcptrace_reader)
+		cells=np.array(list(tcptrace_reader))
+		#drop header row
+		cells= cells[1:]
+		self.cells = cells
 		self.headers=cells[0]
 		self.flows=cells[1:]
 		self.number_of_flows=len(self.flows)
-	# gets cell corresponding to flow with header column 
-	# flow 0 = first one, from 1=subflows
-	def get(self, flow, column):
-		if flow>self.number_of_flows-1:
-			raise Exception("Bad flow index")
-		value = self.flows[flow][self.headers.index(column)]
-		if re.search("[a-zA-Z]", value):
-			return value
-		elif re.search("\.", value):
-			return float(value)
-		elif re.search("^[0-9]+$", value):
-			return int(value)
-		else:
-			return value
-
-	# returns first packet time of flow
-	def first_packet(self, flow):
-		return float(self.flows[flow][self.header_index("first_packet")])-float(self.flows[0][self.header_index("first_packet")])
-	# util: get column index based on header name
-	def header_index(self, column):
-		return self.headers.index(column)
-	
-
-	
-
-
-
-
-#t = TcptraceData("client.pcap")
-#print t.number_of_flows
-#print t.first_packet(1)
-
-
-
-
-
+	def get_csv(self, name):
+		return self.cells
diff --git a/src/mpValidations.py b/src/mpValidations.py
index d41f012..6b7722b 100644
--- a/src/mpValidations.py
+++ b/src/mpValidations.py
@@ -47,72 +47,42 @@ class ExactValueValidation(Validation):
 		self.value = value
 		return self.compared==value
 
-# individual flow validations (used with FlowsTest)
-###################################################
 
-class MinDelayValidation(Validation):
-        # receives flow_spec = (index, flows) where index is the index of the flow to validate, and flows is the array of flows
-	def validate(self, flow_spec):
-		(yml,trace) = flow_spec
-		index=yml["index"]
-		val = trace.first_packet(index)-trace.first_packet(0)
-		self.value = val
-		return self.compared<=val
-
-class MinDelayBetweenValidation(Validation):
-        # gets flow_spec = ( [ index0, index1] , flows) where:
-        #                      - index0 is the index of the flow taken as reference for timing
-        #                      - index1 is the flow for which we want to validate the timing
-        #                      - flows is the array of flows
-	def validate(self, flow_spec):
-		(yml ,trace) = flow_spec
-		[index0, index1] = yml["index"]
-		val = trace.first_packet(index1)-trace.first_packet(index0)
-		self.value = val
-		return self.compared<=val
-
-class AttributeValidation(Validation):
-	def setup(self, flow_spec):
-		(yml ,trace) = flow_spec
-		[index0, index1] = yml["index"]
-		self.val0 = trace.get(index0, yml["attribute"]) 
-		self.val1 = trace.get(index1, yml["attribute"])
-
-class AttributeMinimumDifferenceValidation(AttributeValidation):
-	def validate(self, flow_spec):
-		self.setup(flow_spec)
-		self.value = self.val1 - self.val0
+# the method get_tested_value of the tester returns the value passed to validate.
+# the CsvTester returns an array of values
+class MinDifferenceValidation(Validation):
+	def validate(self, value):
+		v = value.flatten()
+		if len(v)>2:
+			raise Exception("MinDifferenceValidation requires 2 values maximum, not "+ str(len(v)))
+		self.value = float(v[1])-float(v[0])
 		return self.compared<=self.value
-
-class AttributeMaximumDifferenceValidation(AttributeValidation):
-	def validate(self, flow_spec):
-		self.setup(flow_spec)
-		self.value = self.val1 - self.val0
-		return self.compared>=self.value
-
-
-class AttributeMinimumRatioValidation(AttributeValidation):
-	def validate(self, flow_spec):
-		self.setup(flow_spec)
-		self.value = float(self.val1)/+float(self.val1)
+class MinRowsValidation(Validation):
+	def validate(self, value):
+		self.value =  len(value)
 		return self.compared<=self.value
-
-class AttributeMaximumRatioValidation(AttributeValidation):
-	def validate(self, flow_spec):
-		self.setup(flow_spec)
-		self.value = float(self.val1)/float(self.val0)
+class MaxRowsValidation(Validation):
+	def validate(self, value):
+		self.value =  len(value)
+		return self.compared>=self.value
+class ExactRowsValidation(Validation):
+	def validate(self, value):
+		self.value =  len(value)
+		return self.compared==self.value
+class MaxRatioValidation(Validation):
+	def validate(self, value):
+		v = value.flatten()
+		if len(v)>2:
+			raise Exception("MinDifferenceValidation requires 2 values maximum, not "+ str(len(v)))
+		self.value = float(v[1])/(float(v[0])+float(v[1]))
 		return self.compared>=self.value
-
-# mptcptrace csv validations
-############################
-
 # validates all values passed have increasing values
 # it is the Tester's get_tested_value method that does the work
 # to extract the values list from the trace.
-class IncreasingValueValidation(AttributeValidation):
+class IncreasingValuesValidation(Validation):
 	def validate(self, values):
 		previous = 0
-		for i,v in enumerate(values):
+		for i,v in enumerate(values.flatten()):
 			#print i, "{:10.6f}".format(previous), "{:10.6f}".format(v)
 			if v<previous:
 				self.value= "row " + str(i) # index of error row 
@@ -122,15 +92,16 @@ class IncreasingValueValidation(AttributeValidation):
 		return True
 
 
+
 class Tester:
 	def __init__(self, yml, trace):
-		self.yml = yml["validations"]
+		self.yml = yml
 		self.trace = trace
 	# performs a validation found in the yml file.
 	def validate(self):
 		is_ok = True
 		self.logs = ""
-		for val in self.yml:
+		for val in self.yml["validations"]:
 			tested_value = self.get_tested_value(val) 
 			klass_name=val["name"].title().replace("_","")+"Validation"
 			tester_klass=globals()[klass_name]
@@ -156,36 +127,15 @@ class Tester:
 
 
 
-# Base class testing tcptrace results
-# the inheriting class should implement get_tested_value(self, yml)
-# the get_tested_value should return the value that all validations of this test will use
-# the validations get this value as argument of their validate method
-# The validate method iterates one the validations mentioned for the test in the yml file.
-class TcptraceTest(Tester):
-	pass
+class CsvTest(Tester):
+	def get_tested_value(self, validation):
+		a =  self.trace.get_csv(self.yml["csv"])
+		if "rows" in self.yml:
+			a = a[self.yml["rows"]]
+		if "columns" in self.yml:
+			a = a[:,self.yml["columns"]]
+		return a
 
-# get_tested_value returns the number of flows
-class NumberOfFlowsTest(TcptraceTest):
-	def get_tested_value(self, yml):
-		return self.trace.number_of_flows
-
-# get_tested_value returns index of the flow to validate, and the list of flows
-# index can be a compound value, as in the case of min_delay_between where it is an array of indexes
-class FlowsTest(TcptraceTest):
-	def get_tested_value(self, yml):
-		return (yml,self.trace) 
-
-
-
-		
-class MptcptraceTest(Tester):
-	pass
-
-# get_tested_value returns the number of flows
-class ColumnValuesTest(TcptraceTest):
-	def get_tested_value(self, yml):
-		a =  self.trace.get(yml["csv"])
-		return a[:,yml["column"]]
 
 class Checker:
 	def check(self):
diff --git a/src/tests/base/validation.yml b/src/tests/base/validation.yml
index f1f5929..d553524 100644
--- a/src/tests/base/validation.yml
+++ b/src/tests/base/validation.yml
@@ -1,56 +1,44 @@
 mptcptrace:
-  - test: "column_values" 
+  - test: "csv"
+    csv: "c2s_seq_1"
+    columns: 2
     validations:
-      - name: "increasing_value"
-        csv: "c2s_seq_1"
-        column: 2
+      - name: "increasing_values"
         desc: "dummy: check sequence numbers grow"
 tcptrace:
-  - test: "number_of_flows"
+  - test: "csv"
+    csv: "tcptrace"
+    rows: [0,1]
+    columns: [5]
     validations:
-      - name: "min_value"
+      - name: "min_difference"
         target: 2
-        desc: "Open minimum 2 flows"
-      - name: "max_value"
-        target: 4
-        desc: "Open maximum 4 flows"
-      - name: "exact_value"
-        target: 4
-        desc: "Open exactly 4 flows"
-  # This tests the flows opened by the connection. See class FlowsTest
-  - test: "flows"
+        desc: "minimum difference of opening time"
+  - test: "csv"
+    csv: "tcptrace"
     validations:
-      # validates time between first packets of the first stream and the stream for which the index is passed. 
-      - name: "min_delay"
-        index: 1
+      - name: "min_rows"
         target: 2
-        desc: "Minimum 2 seconds delay between opening of first and second flow"
-      # validates time between first packets of streams for which the index is passed. 
-      # index is now a compound value, handled by the validate method of the class MinDelayBetweenValidation
-      # first index value is the base flow we compare to
-      # second index is the flow we want to validate
-      - name: "min_delay_between"
-        index:
-          - 1
-          - 2
-        target: 1
-        desc: "Minimum 1 second delay between opening of second and third flow"
-      - name: "attribute_minimum_difference"
-        attribute: "first_packet"
-        # first index value is the base flow we compare to
-        # second index is the flow we want to validate
-        index:
-          - 0
-          - 1
+        desc: "minimum number of flows"
+      - name: "max_rows"
+        target: 5
+        desc: "minimum number of flows"
+      - name: "exact_rows"
+        target: 4
+        desc: "minimum number of flows"
+  - test: "csv"
+    csv: "tcptrace"
+    rows: [1,2]
+    columns: [5]
+    validations:
+      - name: "min_difference"
         target: 2
-        desc: "first packet delay 2nd flow"
-      - name: "attribute_maximum_ratio"
-        attribute: "total_packets_a2b"
-        # first index value is the base flow we compare to
-        # second index is the flow we want to validate
-        index:
-          - 0
-          - 1
-        # flows[1].packets_a2b/flows[2].packets_a2b < 5%
+        desc: "minimum difference of opening time between flow 2 and 3"
+  - test: "csv"
+    csv: "tcptrace"
+    rows: [0,1]
+    columns: [7]
+    validations:
+      - name: "max_ratio"
         target: 0.05
-        desc: "a->b packet ration flow 2 compard to flow1"
+        desc: "max ration of packet a->b on flow 1 compared to flow 0."