diff --git a/instant-segment/src/test_data.rs b/instant-segment/src/test_data.rs
index d15b1ad..04fe22b 100644
--- a/instant-segment/src/test_data.rs
+++ b/instant-segment/src/test_data.rs
@@ -5,7 +5,7 @@ use std::io::{BufRead, BufReader};
 use std::path::PathBuf;
 use std::str::FromStr;
 
-use super::Segmenter;
+use super::{HashMap, Segmenter};
 
 #[test]
 fn test_data() {
@@ -14,25 +14,31 @@ fn test_data() {
 
 pub fn segmenter() -> Segmenter {
     let dir = PathBuf::from(format!("{}/../data", env!("CARGO_MANIFEST_DIR")));
+    let mut ln = String::new();
 
     let uni_file = dir.join("unigrams.txt");
-    let reader = BufReader::new(File::open(&uni_file).unwrap());
-    let unigrams = reader.lines().enumerate().map(move |(i, ln)| {
-        let ln = ln.unwrap_or_else(|e| panic!("line error at {:?}:{}: {}", uni_file, i, e));
+    let mut reader = BufReader::new(File::open(&uni_file).unwrap());
+    let mut i = 0;
+    let mut unigrams = HashMap::default();
+    while reader.read_line(&mut ln).unwrap() > 0 {
+        i += 1;
         let split = ln
             .find('\t')
             .unwrap_or_else(|| panic!("no tab found in {:?}:{}", uni_file, i));
 
         let word = ln[..split].into();
-        let p = usize::from_str(&ln[split + 1..])
+        let p = usize::from_str(&ln[split + 1..].trim())
             .unwrap_or_else(|e| panic!("error at {:?}:{}: {}", uni_file, i, e));
-        (word, p as f64)
-    });
+        unigrams.insert(word, p as f64);
+        ln.clear();
+    }
 
     let bi_file = dir.join("bigrams.txt");
-    let reader = BufReader::new(File::open(&bi_file).unwrap());
-    let bigrams = reader.lines().enumerate().map(move |(i, ln)| {
-        let ln = ln.unwrap_or_else(|e| panic!("line error at {:?}:{}: {}", bi_file, i, e));
+    let mut reader = BufReader::new(File::open(&bi_file).unwrap());
+    let mut i = 0;
+    let mut bigrams = HashMap::default();
+    while reader.read_line(&mut ln).unwrap() > 0 {
+        i += 1;
         let word_split = ln
             .find(' ')
             .unwrap_or_else(|| panic!("no space found in {:?}:{}", bi_file, i));
@@ -44,11 +50,12 @@ pub fn segmenter() -> Segmenter {
 
         let word1 = ln[..word_split].into();
         let word2 = ln[word_split + 1..score_split].into();
-        let p = usize::from_str(&ln[score_split + 1..])
+        let p = usize::from_str(&ln[score_split + 1..].trim())
             .unwrap_or_else(|e| panic!("error at {:?}:{}: {}", bi_file, i, e));
 
-        ((word1, word2), p as f64)
-    });
+        bigrams.insert((word1, word2), p as f64);
+        ln.clear();
+    }
 
-    Segmenter::from_iters(unigrams, bigrams)
+    Segmenter::from_maps(unigrams, bigrams)
 }