1 files changed, 123 insertions, 0 deletions
diff --git a/numpy/lib/twodim_base.py b/numpy/lib/twodim_base.py
new file mode 100644
index 000000000..b21532ea6
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+++ b/numpy/lib/twodim_base.py
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+""" Basic functions for manipulating 2d arrays
+
+"""
+
+__all__ = ['diag','eye','fliplr','flipud','rot90','tri','triu','tril',
+           'vander']
+
+from numeric import *
+import sys
+
+def fliplr(m):
+    """ returns an array m with the rows preserved and columns flipped 
+        in the left/right direction.  Works on the first two dimensions of m. 
+    """
+    m = asarray(m)
+    if m.ndim < 2:
+        raise ValueError, "Input must be >= 2-d."
+    return m[:, ::-1]
+
+def flipud(m):
+    """ returns an array with the columns preserved and rows flipped in
+        the up/down direction.  Works on the first dimension of m.
+    """
+    m = asarray(m)
+    if m.ndim < 1:
+        raise ValueError, "Input must be >= 1-d."
+    return m[::-1]
+
+def rot90(m, k=1):
+    """ returns the array found by rotating m by k*90
+    degrees in the counterclockwise direction.  Works on the first two
+    dimensions of m. 
+    """
+    m = asarray(m)
+    if m.ndim < 2:
+        raise ValueError, "Input must >= 2-d."
+    k = k % 4
+    if k == 0: return m
+    elif k == 1: return fliplr(m).transpose()
+    elif k == 2: return fliplr(flipud(m))
+    else: return fliplr(m.transpose())  # k==3
+
+def eye(N, M=None, k=0, dtype=int_):
+    """ eye returns a N-by-M 2-d array where the  k-th diagonal is all ones, 
+        and everything else is zeros.
+    """
+    if M is None: M = N
+    m = equal(subtract.outer(arange(N), arange(M)),-k)
+    return m.astype(dtype)
+
+def diag(v, k=0):
+    """ returns the k-th diagonal if v is a array or returns a array 
+        with v as the k-th diagonal if v is a vector.
+    """
+    v = asarray(v)
+    s = v.shape
+    if len(s)==1:
+        n = s[0]+abs(k)
+        res = zeros((n,n), v.dtype)
+        if (k>=0):
+            i = arange(0,n-k)
+            fi = i+k+i*n
+        else:
+            i = arange(0,n+k)
+            fi = i+(i-k)*n
+        res.flat[fi] = v
+        return res
+    elif len(s)==2:
+        N1,N2 = s
+        if k >= 0:
+            M = min(N1,N2-k)
+            i = arange(0,M)
+            fi = i+k+i*N2
+        else:
+            M = min(N1+k,N2)
+            i = arange(0,M)
+            fi = i + (i-k)*N2
+        return v.flat[fi]
+    else:
+            raise ValueError, "Input must be 1- or 2-d."
+
+
+def tri(N, M=None, k=0, dtype=int_):
+    """ returns a N-by-M array where all the diagonals starting from
+        lower left corner up to the k-th are all ones.
+    """
+    if M is None: M = N
+    m = greater_equal(subtract.outer(arange(N), arange(M)),-k)
+    return m.astype(dtype)
+
+def tril(m, k=0):
+    """ returns the elements on and below the k-th diagonal of m.  k=0 is the
+        main diagonal, k > 0 is above and k < 0 is below the main diagonal.
+    """
+    m = asarray(m)
+    out = multiply(tri(m.shape[0], m.shape[1], k=k, dtype=m.dtype),m)
+    return out
+
+def triu(m, k=0):
+    """ returns the elements on and above the k-th diagonal of m.  k=0 is the
+        main diagonal, k > 0 is above and k < 0 is below the main diagonal.
+    """
+    m = asarray(m)
+    out = multiply((1-tri(m.shape[0], m.shape[1], k-1, m.dtype)),m)
+    return out
+
+
+# borrowed from John Hunter and matplotlib
+def vander(x, N=None):
+    """
+    X = vander(x,N=None)
+
+    The Vandermonde matrix of vector x.  The i-th column of X is the
+    the i-th power of x.  N is the maximum power to compute; if N is
+    None it defaults to len(x).
+
+    """
+    x = asarray(x)
+    if N is None: N=len(x)
+    X = ones( (len(x),N), x.dtypechar)
+    for i in range(N-1):
+        X[:,i] = x**(N-i-1)
+    return X