diff --git a/.gitignore b/.gitignore
index 345ceec..3564e40 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,4 @@
 !/readme.md
 !/strichliste.lua
 !/.gitignore
+!/collapse_log.lua
diff --git a/collapse_log.lua b/collapse_log.lua
new file mode 100644
index 0000000..cfba345
--- /dev/null
+++ b/collapse_log.lua
@@ -0,0 +1,34 @@
+
+local function read_log()
+    local log = io.open("log", "r")
+    if log == nil then
+        return function() return nil end
+    end
+    local lines = log:lines("l")
+    return function()
+        local l = lines()
+        if l == "" or l == nil then
+            return nil
+        end
+        local time, username, amount, comment = string.match(l, "(%d+),([%w_ -]+),(-?%d+),([%w_ -]*)")
+        return tonumber(time), username, tonumber(amount), comment
+    end
+end
+
+
+local function balances()
+    local users = {}
+    for _, username, amount, _ in read_log() do
+        users[username] = (users[username] or 0) + amount
+    end
+    return users
+end
+
+local newlog = io.open("log_collapsed","w+")
+if newlog == nil then
+    return print("error failed to open log")
+end
+for username, amount in pairs(balances()) do
+    newlog:write(string.format("%d,%s,%d,%s\n", os.time(), username, amount, "Collapsed transaction history"))
+end
+newlog:close()