Add util because I cannot remember why I would ignore it

.gitignore

@@ -2,4 +2,3 @@ __pycache__
 assess_learners/Data
 data
 grading
-util.py

util.py

@@ -0,0 +1,48 @@
+"""MLT: Utility code.
+
+Copyright 2017, Georgia Tech Research Corporation
+Atlanta, Georgia 30332-0415
+All Rights Reserved
+"""
+
+import os
+import pandas as pd
+
+def symbol_to_path(symbol, base_dir=None):
+    """Return CSV file path given ticker symbol."""
+    if base_dir is None:
+        base_dir = os.environ.get("MARKET_DATA_DIR", '../data/')
+    return os.path.join(base_dir, "{}.csv".format(str(symbol)))
+
+def get_data(symbols, dates, addSPY=True, colname = 'Adj Close'):
+    """Read stock data (adjusted close) for given symbols from CSV files."""
+    df = pd.DataFrame(index=dates)
+    if addSPY and 'SPY' not in symbols:  # add SPY for reference, if absent
+        symbols = ['SPY'] + list(symbols) # handles the case where symbols is np array of 'object'
+
+    for symbol in symbols:
+        df_temp = pd.read_csv(symbol_to_path(symbol), index_col='Date',
+                parse_dates=True, usecols=['Date', colname], na_values=['nan'])
+        df_temp = df_temp.rename(columns={colname: symbol})
+        df = df.join(df_temp)
+        if symbol == 'SPY':  # drop dates SPY did not trade
+            df = df.dropna(subset=["SPY"])
+
+    return df
+
+def plot_data(df, title="Stock prices", xlabel="Date", ylabel="Price"):
+    import matplotlib.pyplot as plt
+    """Plot stock prices with a custom title and meaningful axis labels."""
+    ax = df.plot(title=title, fontsize=12)
+    ax.set_xlabel(xlabel)
+    ax.set_ylabel(ylabel)
+    plt.show()
+
+def get_orders_data_file(basefilename):
+    return open(os.path.join(os.environ.get("ORDERS_DATA_DIR",'orders/'),basefilename))
+
+def get_learner_data_file(basefilename):
+    return open(os.path.join(os.environ.get("LEARNER_DATA_DIR",'Data/'),basefilename),'r')
+
+def get_robot_world_file(basefilename):
+    return open(os.path.join(os.environ.get("ROBOT_WORLDS_DIR",'testworlds/'),basefilename))