diff --git a/merge.py b/merge.py
index bf0e5ac..ea8a1b0 100755
--- a/merge.py
+++ b/merge.py
@@ -2,20 +2,38 @@
 
 import csv
 import lzma
+from datetime import date, timedelta
 
 result = []
-sensorlist = [1,2,4,8,11,12,13,14,15,16,17,18,19,20]
-for i in sensorlist:
-	no = str(i)
-	r1 = csv.DictReader(lzma.LZMAFile("/home/tutimura/public_html/cgi-bin/ondotori/data/"+no+"/201612.csv.xz"), fieldnames=["datetime", "temp-"+no, "humid-"+no])
-	result+=list(r1)
+sensorlist = [1,2,3,4,5,6,7,8,9,11,12,13,14,15,16,17,18,19,20]
 
-for i in sensorlist:
-	no = str(i)
-	r1 = csv.DictReader(lzma.LZMAFile("/home/tutimura/public_html/cgi-bin/ondotori/data/"+no+"/201701.csv.xz"), fieldnames=["datetime", "temp-"+no, "humid-"+no])
-	result+=list(r1)
+def gather_data(frm, to, which):
+	global result
+	if which == 0:
+		dbdate = frm
+	else:
+		dbdate = to
+	dname = "%04d%02d" % (dbdate.year, dbdate.month)
+	frm_s = frm.strftime("%Y/%m/%d 00:00")
+	to_s  = to.strftime("%Y/%m/%d 00:00")
+	tmplist = []
+	for i in sensorlist:
+		no = str(i)
+		fname = "/home/tutimura/public_html/cgi-bin/ondotori/data/"+no+"/"+dname+".csv.xz"
+		r1 = csv.DictReader(lzma.LZMAFile(fname), fieldnames=["datetime", "temp-"+no, "humid-"+no])
+		tmp=filter(lambda x: x["datetime"] >= frm_s and x["datetime"] <= to_s, r1)
+		if tmp == []: continue
+		tmplist.append(tmp)
+	result += [x for s in zip(*tmplist) for x in s]
 
-#result = sum(result,[])  #flatten list of list
+to = date.today()
+frm = to - timedelta(15)
+
+gather_data(frm, to, 0)
+if frm.month != to.month:
+	gather_data(frm, to, 1)
+
+# align on 10 min.
 for i in range(len(result)):
 	result[i]["datetime"] = result[i]["datetime"][:-1]+"0"
 	
@@ -31,7 +49,5 @@
 		fa.append(entry)
 	prev = entry["datetime"]
 
-
-fa = fa[::2]
 print "var data = "
 print fa
diff --git a/update.py b/update.py
new file mode 100755
index 0000000..f18f48a
--- /dev/null
+++ b/update.py
@@ -0,0 +1,74 @@
+#!/usr/bin/python
+
+import csv
+import lzma
+import sys
+import os
+from datetime import date
+
+n_returns = 600
+sensorlist = [1,2,3,4,5,6,7,8,9,11,12,13,14,15,16,17,18,19,20]
+
+
+frm = sys.argv[1]
+to  = sys.argv[2]
+div = sys.argv[3]
+
+frm_y, frm_m, frm_d = [int(x) for x in frm.split('/')]
+to_y,  to_m,  to_d  = [int(x) for x in  to.split('/')]
+
+frm = date(frm_y, frm_m, frm_d)  # align for naughty input
+to  = date(to_y, to_m, to_d)     # align for naughty input
+ 
+# retreive from database
+# first, calculate culling idx
+samples_per_day = 24 * 6
+ndays = (to - frm).days * samples_per_day
+step  = int(ndays / n_returns) + 1
+
+result = []
+while frm.year < to.year or frm.month <= to.month:
+	tmplist = []
+	for i in sensorlist:
+		no = str(i)
+		fname = "/home/tutimura/public_html/cgi-bin/ondotori/data/"+ no+
+		        "/"+frm.strftime("%Y%m")+".csv.xz"
+		try:
+			xz = lzma.LZMAFile(fname)
+			r1 = csv.DictReader(xz, fieldnames=["datetime", "temp-"+no, "humid-"+no])
+			frm_s = frm.strftime("%Y/%m/%d 00:00")
+			to_s  = to.strftime("%Y/%m/%d 00:00")
+			tmp=filter(lambda x: x["datetime"] >= frm.strftime("%Y/%m/%d") + " 00:00" 
+				and x["datetime"] <= to + " 23:59", r1)
+			if tmp == []: continue
+			tmplist.append(tmp[::step])
+		except IOError:
+			break
+	result += [x for s in zip(*tmplist) for x in s]
+
+	frm_m += 1
+	if frm_m > 12:
+		frm_y += 1
+		frm_m = 1
+
+# align on 10 minite
+for i in range(len(result)):
+	result[i]["datetime"] = result[i]["datetime"][:-1]+"0"
+	
+#result.sort(key=lambda x: x["datetime"])  # maybe not needed
+
+# gather all sensors
+prev=""
+fa = []
+for entry in result:
+	if entry["datetime"] == prev:
+		fa[-1] = {k: v for dic in [entry, fa[-1]]
+			for k, v in dic.items()}
+	else:
+		fa.append(entry)
+	prev = entry["datetime"]
+
+# cull data to fit about 2000 entries
+print (fa)
+print fa
+